Thoughts on smokeless powder in the .45-75 Winchester 1876

Post by **Hobie** » Thu Jan 15, 2009 7:01 pm

Well, I have one. Have done a bit of case production and reloading. Just a bit. Others here like Grizzly Adams, John Boy, Larryo, Coyote Nose and Buck Stinson (by a long shot!) have done a lot more loading and shooting as well. Over at CAS City we had a bit of a tiff when loading this case with blasphemous smokeless powders was mentioned. Some other fellows (not any of those mentioned above) got tied in a knot over the idea. It is unfortunate, but it may come to pass in the short run that we'll have to load smokeless to shoot these guns. It just might be that explosive BP will be very much more restricted (just call me paranoid and then humor the supposition).

Lyman's 49th edition of their loading manual was recently released. In it Brian Pearce has an article concerning loading of the Winchester 1876 replicas/reproductions. FWIW, he used Chaparral rifles. In that article, Mr. Pearce says that the MODERN 1876s can handle 28K CUP pressures. No where does he say how he came to that conclusion.

He also provides loading data for the .40-65, .45-60, and .45-75. In the .45s he uses the same Lyman 457191 and 457122 bullets. These are nominally 292 and 330 gr. respectively. He did not use the standard 350 gr. 457192 in the .45-75. Pity. It appears that he loaded based on the 28K CUP limit.

Powders used include IMR and H 4198, H4895, Varget, Pyrodex Pistol pellets (30 gr.), Trail Boss, 2400, AA2015 and AA5744 (XMP5744). Charges are a bit all over the place with some likely producing pressures of sub 15K CUP and others quite a bit more (the last is a supposition on my part based on my personal experience). No pressure data is given. After having read the article it would appear (perhaps due to editing) that he simply thought this or that powder would do well and used it. I don't suppose that he damaged any rifles, but I don't know one way or the other.

To narrow it down a bit more, I'd like to use H4198. IMR 4198 (and H4198 is the next slowest in the burn rate chart) has long been used as a sub for BP in the English express cartridges at a rate of 40% of the BP charge. That would be 30 gr. for a 75 gr. charge or 28 gr. for a 70 gr. charge in a more modern case. His lower charges with lighter bullets produce better results than is my experience in my carbine (22" barrel). I've re-read his article a number of times and can't shake this feeling that there's some sort of disconnect. IOW, something isn't quite right somewhere. Whether it is with me, my rifle, or with Mr. Pearce and/or his rifle, I don't know.

Again, while I'd rather use BP I realize that there may be reasons in the future I won't be able to. I'd like to prepare for those contingencies.

So, what do you shooters of the toggle-link guns, specifically the 1876 and its reproductions think? Have you read the article? What do you do?

Old Time Hunter · Post by **Old Time Hunter** » Thu Jan 15, 2009 7:37 pm

Hobie, can't speak for the toggle-linkage handling what kind of pressure, but I too have read the article. What I can speak to is that I load the heck out of BP cartridge loads along with smokeless loads for original Springfield Trapdoors. We all know that the Trapdoor action is even less stout than the '76 toggle. Loading 28-28.5 grains of H4198 behind a 405 grain LFN yields 1275-1325 fps out of my '73 Trapdoor rifle and 1180-1210 fps out of my '79 and '84 carbine's. I get absolutely no breach movement. Raising it to 30 grains of H4198 yields 1440 fps out of the rifle and 1305 fps ave out of my carbines, with the rifle showing some breach block movement by the latch moving against the bottom of the hammer. Surprisingly when I load 62.5 grains of FFg behind a 435gr LRNHB 20-1 cast and a .030 veggie wad, I yield 1480 fps out of my rifle, no breach block movement, and 1420 fps out of the carbines (shows that that is probably just about max loading for the carbines).

Buffboy · Post by **Buffboy** » Thu Jan 15, 2009 8:01 pm

Well I've been shooting my 40-60WCF with IMR3031 for over a year now. I'm just a little over the velocities of my pyrodex loads (1325fps) at 1370fps. I'm using Lee dies and factory crimping(I had one made) cases made from Starline 45-70. I like it, it fills the case to the bullet(Montana Bullet Works, 240gr FNLA sized .406) at 28.0gr with almost no compression. I've shot it in the heat, I've shot it in the cold, the velocities stay right there and it's been pretty accurate. It's not the cleanest burning load but that hasn't seemed to effect accuracy and I've shot 30 rounds at a sitting.

cowboykell · Post by **cowboykell** » Thu Jan 15, 2009 8:14 pm

I shoot a 300 gr. cast bullet over 10 gr. of Trail Boss powder in Bertram cases in an original 45-75 Win 1876. Loads seem wimpy and I haven't shot over my chrony, but I can sure wallop my 100 yd. gong.

Post by **Hobie** » Thu Jan 15, 2009 9:41 pm

Old Time Hunter wrote:Hobie, can't speak for the toggle-linkage handling what kind of pressure, but I too have read the article. What I can speak to is that I load the heck out of BP cartridge loads along with smokeless loads for original Springfield Trapdoors. We all know that the Trapdoor action is even less stout than the '76 toggle. Loading 28-28.5 grains of H4198 behind a 405 grain LFN yields 1275-1325 fps out of my '73 Trapdoor rifle and 1180-1210 fps out of my '79 and '84 carbine's. I get absolutely no breach movement. Raising it to 30 grains of H4198 yields 1440 fps out of the rifle and 1305 fps ave out of my carbines, with the rifle showing some breach block movement by the latch moving against the bottom of the hammer. Surprisingly when I load 62.5 grains of FFg behind a 435gr LRNHB 20-1 cast and a .030 veggie wad, I yield 1480 fps out of my rifle, no breach block movement, and 1420 fps out of the carbines (shows that that is probably just about max loading for the carbines).

Which black powder are you using?

Mike D. · Post by **Mike D.** » Thu Jan 15, 2009 10:34 pm

Although I have not yet loaded for my .45-75, I did load quite a bit for my original 1876 .45-60 back when I owned it. I went as high as 36 grains of IMR 4198 without problems, but settled on 30 grains as my regular load. This was using 330 grain .459 bullets cast by a friend. Back in the '80s, when I bought the old gun for the high price of $400., it was well used, had the original barrel cut from 28" to 22", but was tight and had a super fine bore. Black powder was never used by me and won't be when I get around to the .45-75. I plan on using mostly the same 4198 and will start at 40 grains. This should NOT be extreme for a modern toggle link action. The toggle link '76 is no weak sister by any stretch of the imagination. I ordered 100 Starline .50AK cases from Midway, so the ball should start rolling within a few weeks. I can't wait.

Old Time Hunter · Post by **Old Time Hunter** » Fri Jan 16, 2009 4:42 pm

Hobie wrote:
Old Time Hunter wrote:Hobie, can't speak for the toggle-linkage handling what kind of pressure, but I too have read the article. What I can speak to is that I load the heck out of BP cartridge loads along with smokeless loads for original Springfield Trapdoors. We all know that the Trapdoor action is even less stout than the '76 toggle. Loading 28-28.5 grains of H4198 behind a 405 grain LFN yields 1275-1325 fps out of my '73 Trapdoor rifle and 1180-1210 fps out of my '79 and '84 carbine's. I get absolutely no breach movement. Raising it to 30 grains of H4198 yields 1440 fps out of the rifle and 1305 fps ave out of my carbines, with the rifle showing some breach block movement by the latch moving against the bottom of the hammer. Surprisingly when I load 62.5 grains of FFg behind a 435gr LRNHB 20-1 cast and a .030 veggie wad, I yield 1480 fps out of my rifle, no breach block movement, and 1420 fps out of the carbines (shows that that is probably just about max loading for the carbines).
Which black powder are you using?

Goex

I've tried Pyrodex RS, and it is pretty similar, just stinks more.

Modoc ED · Post by **Modoc ED** » Fri Jan 16, 2009 5:55 pm

Hobie -

Don't you think that so goes the way of black powder shall also go the way of smokeless powder? And then ya got primers to consider too.

Post by **Hobie** » Fri Jan 16, 2009 7:36 pm

Modoc ED wrote:Hobie -

Don't you think that so goes the way of black powder shall also go the way of smokeless powder? And then ya got primers to consider too.

Eventually, maybe. As we roadblock things we might get momentary concessions that will give us some months to continue hoarding. Having lived in such situations where all is rationed I strongly believe in the get-it-while-you-can system. They would have to outlaw shooting completely and set up a complete neighborhood spy system to shut down shooting and that will take a few years yet.

Yes, I'm pessimistic about the future of shooting sports right now...

marlinman93 · Post by **marlinman93** » Fri Jan 16, 2009 9:17 pm

How about just using a substitute like 777?

Old Time Hunter · Post by **Old Time Hunter** » Fri Jan 16, 2009 9:26 pm

Hobie,

Potash, Sulfer, and Charcoal.....seems simple to me!

Post by **Hobie** » Fri Jan 16, 2009 9:33 pm

Old Time Hunter wrote:Hobie,

Potash, Sulfer, and Charcoal.....seems simple to me!

Someday they may be busting BP labs instead of meth labs...

coyote nose · Post by **coyote nose** » Fri Jan 16, 2009 9:46 pm

I just snuck online here at work.....My standard load for the Chaparral 1876 in 45-75 is Triple 7, but I also shoot a lot of Pyrodex RS. I am one of those that wont try the smokeless powders in my toggle link or trapdoor style guns. Even with the new ones. My concern is not the strength of the new metals, it is the ENGINEERING of the design. They were engineered for BP pressure peaks and also the pressure curve of black. Even with the new made repros the firing pin tip on these 1876's are big! A pierced primer would leak a large amount of gas back into the action. If i am not mistaken, a standard modification made to bp era Winchester 1885 single shot (modifying them to smokeless cartridges) was to bush the breech face, redrill it smaller and replace the large firing pin with a smaller diameter tip firing pin. I dont get in a tizzy when people load smokeless in them, I just chose not to do it. As an aside, my original 1873's and trapdoors probably had 10 owners before I got them, and I am sure smokless was shot in them. I once bought an 1873 in 32 WCF off a guy who also gave me a box of ammo with it. It was the remington high power smokeless ammunition! I took the gun apart as I always do with a new antique purchase and sure enough the breech bolt was bent! It had a pronounced curve to it. Had to find a replacement bolt, in the days before ebay it was quite a chore to do and cost me $50 back then (mid 1990's). Anyway, I gave up on true BP after years of testing...with one exception pyrodex always performed better. When i want the smoke and the fuss and the smell andthe mess of BP I use pyrodex, when I dont I use 777. You bring up a good point Hobie...may be time to stock up on some powders.

Post by **Hobie** » Fri Jan 16, 2009 10:40 pm

Thank you.

I don't think WHAT is critical, or might not be critical in the future, as much as being able to do anything/something.

I personally like Pyrodex. IME it gives ballistics very much like GOEX FFg.

KirkD · Post by **KirkD** » Fri Jan 16, 2009 10:45 pm

Sherman Bell's article in the Double Gun Journal was a real urban-myth buster when it comes to pressure curves of slower smokeless powders vs. black powder. In general, Black powder has similar pressure curves to Blue Dot and 2400 for the same ballistics (bullet weight and velocity). Slower smokeless powders have a lower pressure curve for the same ballistics and, thus, are easier on weak actions despite all the urban myths to the contrary. The downside of these slower smokeless powders (such as IMR 4198) is that since they have a lower peak pressure than black powder, they will not 'bump up' the bullet to fill the bore like black powder does. The solution is to use a smokeless powder that is closer to 2400. In my original '76 .45-60, I used 2400 and 5744 with good results. Recently, however, I happened to notice that my best groups with my old 38-55 and an old '86 in 45-70, using cast bullets, were obtained with IMR SR4759. It has a burn rate close to IMR 4227 and 5744, but its DPI and RQ are significantly faster than either of these other two. It is an odd powder, cylindrical in shape, but with a hollow core .... kind of like a thick-walled tube. The bottom line is that, from my limited experience, IMR SR4759 might be the ideal smokeless black powder substitute if one wants to stick with original black powder ballistics. What suits it for this role are two things: a DPI and RQ pretty much identical to BP and the hollow core gives it more bulk for better case-filling than either 2400 or 5744. With that in mind, I've just bought another pound of the stuff to try out in various calibers. The weather here is heinous for shooting, however. This morning is was about 15 degrees below zero Fahrenheight and that is about the story for the week. It will be spring before I can get some serious testing done with SR4759.

20cows · Post by **20cows** » Fri Jan 16, 2009 10:58 pm

The weather here is heinous for shooting, however. This morning is was about 15 degrees below zero Fahrenheight and that is about the story for the week. It will be spring before I can get some serious testing done with SR4759.

Brrrrrrrrrrrrrr!!!!

Kirk, I anxiously await to hear of your results! I may have a '76 to play with this summer.

Post by **Hobie** » Sat Jan 17, 2009 11:54 am

Those pressure graphs were posted someplace (here or at CAS city). BP is an EXPLOSIVE and has a pressure curve to match that description.

IMR SR4759 is what I've been using. I wish there was real pressure data. I believe it is coming.

J Miller · Post by **J Miller** » Sat Jan 17, 2009 12:31 pm

Kirk,
Please translate: DPI and RQ

...................................................................

In my opinion we have enough knowledge and experience with the slow burning smokeless powders that there is little reason to shoot black powder in anything but a true muzzle loader.
The only reason I can think of to shoot BP in a cartridge gun would be to attempt to duplicate an original load you do not have velocity data for. Then use that data to work up the smokeless charges.

JMHO

Joe

KirkD · Post by **KirkD** » Sat Jan 17, 2009 12:44 pm

Joe, there's a good write up here http://www.chuckhawks.com/powder_burning_speed.htm

Also, here are a few graphs from a source that I cannot recall at the moment:

Note that Trailboss has a significantly higher peak pressure than BP. Also note that when you adjust for bullet weight, 4759 comes in pretty close to the FFg pressure curve.

J Miller · Post by **J Miller** » Sat Jan 17, 2009 12:53 pm

Kirk,

Thanks for the link.

Joe

colo native · Post by **colo native** » Sat Jan 17, 2009 1:05 pm

Hobie wrote:Those pressure graphs were posted someplace (here or at CAS city). BP is an EXPLOSIVE and has a pressure curve to match that description.

IMR SR4759 is what I've been using. I wish there was real pressure data. I believe it is coming.

4759 is one I use in my 40-65,,,,tryed 3031, 5477 n others, no luck...

w30wcf · Post by **w30wcf** » Sat Jan 17, 2009 5:19 pm

Kirk,
I had found them on the ASSRA forum compliments of "Duckrider".
http://www.assra.com/cgi-bin/yabb/YaBB. ... 02959756/0

colo native,
I had posted them at Cas City in the "Darksiders Den" to inform those b.p. experts who insisted that smokeless had a faster pressure spike, that was not always the case.

w30wcf

coyote nose · Post by **coyote nose** » Sun Jan 18, 2009 10:34 am

None the less I still wont do it. Frank De Haas in his excellent book "Bolt Action Rifles" mentions the difference between a strong action and a safe action. There is a difference. I believe he was talking about some countries WW2 rifle being very strong, but IF there was a gas leak (ie: cartridge head failed, piereced primer,head separation, bad annealing of the case, overload, plugged bore, etc) then even though the gun is strong, the venting of the gas is poor and thus is not safe. Like some of you, I consider the toggle links stronger than given credit for. Add the better steel in the repros and it may be even stronger. I dont consider it a safe design though. The incident about 6 or 7 years ago now where the shooter had an 1873 firing pin blow out the back of the receiver, cock back the hammer, blow through his safety glasses and bury itself in the back of his eye socket is the most graphic and tragic example of what can happen. He used smokeless and I dont remember what the final verdict was, I think it was an overcharge and not firing out of battery. Not saying it cant happen w/BP or its substitutes, just seems I only hear about examples like this, or near misses, when smokeless is used. That 73 (and 76) pin and bolt was actually called a "breech piston" by Winchester and it really acts that way if high pressure gas gets in there! The fact the firing pin was able to blow right through that shooters safety glasses is stunning. Something to keep in mind with these designs originally engineered for the Volcanics some 150 years ago.

Post by **Hobie** » Sun Jan 18, 2009 12:18 pm

The thing is, simply using BP doesn't negate that kind of risk. We know that because such things happened with BP which is why there was a demand for safer actions.

I got to shoot my '76 a bit this morning. Not much as I didn't want to tick off Mom's neighbors but I did want them to know I was there. Anyway, I had two failures to fire at first strike but both of those rounds went off with the second hammer blow. Ten-X ammo in Bertram cases. Smokeless (IMR SR4759 is what it looks like).

Grizzly Adams · Post by **Grizzly Adams** » Sun Jan 18, 2009 5:40 pm

coyote nose wrote: I dont consider it a safe design though. The incident about 6 or 7 years ago now where the shooter had an 1873 firing pin blow out the back of the receiver, cock back the hammer, blow through his safety glasses and bury itself in the back of his eye socket is the most graphic and tragic example of what can happen. He used smokeless and I dont remember what the final verdict was, I think it was an overcharge and not firing out of battery. Not saying it cant happen w/BP or its substitutes, just seems I only hear about examples like this, or near misses, when smokeless is used. That 73 (and 76) pin and bolt was actually called a "breech piston" by Winchester and it really acts that way if high pressure gas gets in there! The fact the firing pin was able to blow right through that shooters safety glasses is stunning. Something to keep in mind with these designs originally engineered for the Volcanics some 150 years ago.

No disrespect intended, but I have been hearing this story for at least 12 years now, and I can't find one shred of evidence or an eye witness that can confirm it! If anyone can do so, I would like to know if this be truth or urban myth!

The Uberti 73 is arguably the most popular rifle in the CAS community, and at least 98% of them are shoot exclusively with smokeless - and shot a LOT!

In the case of the new 76s, your attention called to this pic which shows the firing pin "key" that retains the firing pin extension on the Uberti 76 (Uberti uses a two piece FP/FE). Before you shear this baby, you are going to have more trouble that just a firing pin adrift!

Pic of firing pin key/retainer showing interface with bolt and firing pin extension.

Pic showing "key" or retainer in place.

This pic of the inside of a Winchester 1876, illustrates the difference between the original and the Uberti copy shown in 1 and 2 above.

Note that Uberti has modified the original "firing pin retractor" by only using the top half. The original firing pin was solid, and the retractor pivoted off the link to withdrawn the firing pin. The new system serves to capture the firing pin extention, while retraction is effected by the coil spring seen on the firing pin in pic #1.

FWIW, the Chaparral version uses the same design as the original Winchester 1876.

Also, Uberti proofed their 1876 for smokeless!

I have a Uberti 76 in 45-60. I have had good luck with 25.8 grains of H4198 under a 300 bullet. I have gone as high as 31.6 grains of H4198, but accuracy was poor with that load. H4895 also shows promise.

Good topic!

Post by **Hobie** » Sun Jan 18, 2009 5:48 pm

Let's move this to another angle.

.45-70 Govt loads using various powders are a known quantity. I believe somebody mentioned their Trapdoor in this or another topic in this regard. While it isn't always wise to extrapolate data, the .45-75 has about the same capacity as the .45-70 albeit in a bottle necked case. Tests have shown (even back in the 1870s and 1880s) that the bottle necked cases of similar capacity and charge will give about 2K CUP more pressure than the straight case version. This is one reason the US Govt went with the kinda straight cased .45-70. Assuming the same bullet being used, if a given charge with a given bullet is OK for the Trapdoor, why then would it not be ok in the 1876? About if one allowed .5-1 gr. reduction in the .45-75 to allow for that pressure increase?

Just call me a pot stirrer...

Grizzly Adams · Post by **Grizzly Adams** » Sun Jan 18, 2009 6:44 pm

Hobie wrote:Let's move this to another angle.

Assuming the same bullet being used, if a given charge with a given bullet is OK for the Trapdoor, why then would it not be ok in the 1876? About if one allowed .5-1 gr. reduction in the .45-75 to allow for that pressure increase?

Just call me a pot stirrer...

Hand me that spoon!

That's the conclusion I have reached, at least as a starting point in powder selection and beginning load development. I do think that it is important to verify with a chronograph to keep the velocities in the BP envelope.

Post by **Hobie** » Sun Jan 18, 2009 6:50 pm

Grizzly Adams wrote: That's the conclusion I have reached, at least as a starting point in powder selection and beginning load development. I do think that it is important to verify with a chronograph to keep the velocities in the BP envelope.

Yes, when velocities have exceeded the BP "envelope" so have pressures.

So, the old 40% rule would say that in the .45-75 a charge of 30 gr. IMR 4198 under the 350 gr. bullet would match the old BP velocities. IME, the printed maxs are 24-26 gr. and these give the expected medicore performance, both in terms of velocity (sub BP "envelope") and accuracy.

coyote nose · Post by **coyote nose** » Sun Jan 18, 2009 7:31 pm

Grizzly, absolutely no disrespect taken. Simply email me your email and I will scan the 3 articles and email them to you. They appeared in the quarterly "Black Powder Cartridge News" Fall and Winter 1997 and spring 1998. The match was in Miles City Montana, the gun a Uberti 1873 with the firing pin as in the photos you posted. Load was a smokeless load.
From Fall 1997 "When the cartridge exploded the resulting force blew the rifle apart, sending a large chunk of metal through Ralphs safety glasses. It stopped only after partially fracturing the skull behind the eye cavity. Had it not been for the safety glasses slowing it down, Ralph might not be with us today". Then it details the EMT attention, the hospitals he was taken to etc. It then mentions the rifle being sent to a Billings Montanagunsmith for examination. There are pictures of the busted toggles, bent breech bolt (bent like the one I mention was in my 32-20 1873), the bulged case.
The winter issue gets more technical, and details computed bolt thrust, etc, and mentions the load. He als mentions a sharps rifle blown up with smoikeless,then adds: "Aside from Elmer Keith bursting the cylinder of an old SAA .45 Colt using FFFg and 300 grain bullets, I have never heard of a cartridge gun being burst by blackpowder. Those burst with smokeless powder are legion however"
The spring issue is a letter to the editor.
Venturino mentioned this accident a few times. All in all if it were a legend I believe it would be debunked by now.
Anyway, your photos are interesting....I have a Chaparral 1876 (as I believe Hobie does) and they use the one piece firing pin like the original. I did not know Uberti 1876's use the 2 piece pins. I wonder if there are any other differences.

Grizzly Adams · Post by **Grizzly Adams** » Sun Jan 18, 2009 8:36 pm

Thanks, for the reply and info, coyote nose. I would very much like a copy of that article. Sent you a PM with my address.

I sure don't dispute the possibility of a fella blowing up a rifle - any rifle with the wrong load. Heck, I know of 1886s that have been blown up! I even saw a fella burst the cylindar on a Ruger Super Blackhawk.

A catastrophic failure such as you report still does not mean these actions are not safe with smokeless. If they weren't I guess we would have SASS shooters laying everywhere!

Obviously, we need to be careful about what we put in any action, and these toggle guns are NOT hot rods!

Other than the two piece firing pin in the Uberti, the design is the same as the Winchester - although that does not translate into interchangeability of all parts! The Chaparral does make that claim.

In terms of the Uberti 73, the current version uses the same firing pin retainer as the new 76, as in the pics. Earlier versions did not use the retainer, relying on a cross pin arrangement instead.

FWIW, I shoot BP in all of my CAS guns, rifles, shotgun and pistols. I just like the smoke and the roar!

Grizzly Adams · Post by **Grizzly Adams** » Sun Jan 18, 2009 9:09 pm

Hobie wrote:
Grizzly Adams wrote: That's the conclusion I have reached, at least as a starting point in powder selection and beginning load development. I do think that it is important to verify with a chronograph to keep the velocities in the BP envelope.
Yes, when velocities have exceeded the BP "envelope" so have pressures.

So, the old 40% rule would say that in the .45-75 a charge of 30 gr. IMR 4198 under the 350 gr. bullet would match the old BP velocities. IME, the printed maxs are 24-26 gr. and these give the expected medicore performance, both in terms of velocity (sub BP "envelope") and accuracy.

I agree.

Those maxs (24-26) were developed, in deference to the old original rifles, and don't perform well in them either!

What kind of velocity are you getting with those loads in your rifle?

Post by **Hobie** » Sun Jan 18, 2009 9:32 pm

I believe I've posted elsewhere but I only got around 950 fps with the traditional "suggested" loads of IMR SR4759 or IMR 4918. H4198 did no better.

I find it interesting that Lyman shows 34 gr. of IMR 4198 (slightly faster than H 4198) in the .45-70 with a 385 gr. bullet at less than 18K CUP but Mr. Pearce stuck with the old standard of 26 gr. 4198 under 457122 in his .45-70 work up. I believe he actually used the same or higher charge in the .45-60! (don't have the book next to me at the moment)

I was just doing a comparison of the .45-70 Trapdoor (sub 18K CUP) and .45-75 loads using IMR 3031. Again, we seem to stick to starting loads in the .45-70 (or less) when using the same powders and bullets in the .45-75. I can't find any reason why.

In most situations it is enough to say that a particular launching system/firearm can handle pressures of X CUP or PSI in a particular cartridge and then stick with those pressures. It would seem that this simply method would apply to the 1876. Anecdotal "evidence" purporting to support the contrary view that the 1876 is somehow susceptible to different pressure curves actually uses cases of excessive pressures brought about by using overly "optimistic" loads. In old, original firearms, the condition of the material used in the construction of those firearms and it's actual condition after 100-130 (or more) years of use is an absolute mystery until the gun is destroyed.

However, I've been circumspect in my review of the Lyman 49th Ed. data because I've noted a tremendous number of typos in the narrative/article portions of the manual. A small thing but if these guys are relying on spell-check rather than a human proof-reader I don't know that I fully trust the rest of the manual. If I don't trust the manual then why have it?

As to have KBs in guns, we've all seen photos of modern Marlin 1895, Mike Venturino's friend "Shrapnel"'s 76, a recent photo of a Ruger SP101, etc, ad naseum. These all prove that ANY gun can be brought to the point of catastrophic failure due to faulty reloading or perhaps shooting practices.

Leverluver · Post by **Leverluver** » Mon Jan 19, 2009 1:29 am

These discussions usually wind up with "camps" so I'll state right off, I'm in the smokeless camp. No problem with black other than I have lost interest in playing with it anymore, and it is getting hard (and will get harder) to obtain. Also, any comments I make are in reference to modern rifles and not of 130-year-old examples.

I have performed numerous (many hundreds) pressure tests on the 45-70, and there is no doubt in my mind that smokeless loads (with the appropriate powders) can be developed for the 45-75 that can achieve equivalent black powder performance at less than black powder peak pressures or develop slightly higher performance loads at pressures not exceeding black powder peak pressures. Thanks to Kirk for his info, which I totally agree with. I knew he had that info and I was waiting for him to jump in before I did

.

To me, the one glaring and unanswered (even unasked) question is the difference (if any) between the breech thrust generated by black loads compared to smokeless loads. I fear there may be far more to it than just contained pressure times the case area. I also believe that the weak link (no pun intended) in the 76 (and it's toggle relatives) is the breech lockup rather than the barrel. IOW, I think the 76 action (as opposed to modern actions) will fail before the (modern steel) barrel fails from excessive pressures. Yes, we all have seen the Winchester write up that describes the test conducted to show the strength of the 76 action; most of which was unadulterated BS marketing hype that would have even made Madoff blush. THEY WERE SELLING RIFLES FOLKS.

As Kirk's info graphically illustrates, black powder IS an explosive and it's pressure curve is quite abrupt. That is usually not a good thing when trying to keeps all pieces and parts intact, but in black powder’s case, the pressure (used in correct volumes) generally does not get high enough to cause problems, even if the pressure spike is abrupt. But that abruptness may serve some useful purpose. Kirk indirectly alluded to it when he mentions the "bump" a bullet receives from black when it is necessary to have the bullet bumped (doubtful if necessary in modern guns but quite often useful in older guns that had undersized chamber throats). That same abruptness that bumps the bullet also bumps the casing. Many on here (Kirk, Grizz A, Griff ad infinitum) can all attest to the improved sealing of the case to the chamber walls when using black powder in 66s and 73s and the like. This is because the abrupt curve quickly forces the case against the chamber walls and gives the most noticeable affect of reduced breech "spitting" when compared to the same case loaded with smokeless. The phenomenon is not at all unlike the tests conducted by Ackley on case design and the resultant grip of the chamber that can greatly reduce breech thrust. The difference is Ackley was using smokeless but at pressures that would expand the case to grip the walls unlike in the 76 where any sane person would not wish to go anywhere near those pressures (with smokeless) to achieve that same chamber grip. The same grip, which is easily attained with black powder. And while we are ruminating the question of case grip, one has to ask the question of the quality of such a grip when using greatly undersized parent cases that will not even have their wall expanded to contact the chamber until after several firings. Just one more thing to keep you awake at night

NOW, the $64,000 question is....just how much of the breech thrust is actually taken up by the case strength alone while the case has a firm grip on the chamber wall? Modern cases are fully capable of absorbing the entire pressure of a 76 appropriate load with no assistance from the breech what so ever. Now I’m not saying that is what is happening; I’m just saying that until someone answers that question, we will not fully know the truth of what is going on when we pull the trigger. Don’t depend on the component companies to answer that question: that will be up to us alone to figure out.

Now Kirk may be right on the money as far as matching “quickness” and possibly the grip of black with smokeless loads. It may also be true that I have gone completely off reservation and there is no chamber gripping going on at all, in which case Grizz A. may be correct that the slower smokeless powders (which will NOT bump or grip) are in fact the way to go. IMHO the 76 and other toggles are in a different class. It may be the black only folks have a valid point. The lower pressure of the slower powders may also have a valid point. All this is yet to be determined. And it won't be determined by firing using SAAMI methodology of pressure peaks alone.

I assure you that if the breech lockup was of no concern to me, you could produce some outrageous loads with slow powders that would pop some eyes but STILL stay well within reasonable 76 pressures. Now give me a Ruger #1 in 45-75 and I’ll take on the world.

As an aside, you folks with full loads of 777 are not as safe as you think you are. You are probably producing pressures a full 20% above black. You’d be better off waiting for the new (weaker) 777 to arrive. At least know you are not “equaling” black pressures.

Chapter two maybe later this spring.

Post by **Hobie** » Mon Jan 19, 2009 8:16 am

Leverluver,

Breech thrust is a topic seldom discussed because we get wrapped up in the overall pressure discussion. Your ideas on what mitigates (or not) breech thrust are interesting. As it is, without regard to propellant, the toggle-link action is much like a revolver in how the case is supported in the chamber. The only difference is that the breech face moves and is supported some distance to the rear. Every time I look at my rifle I'm reminded of the modern Mk 19 Mod 3 40mm MG in which the case hangs out the rear of the chamber. It can be disconcerting.

Triple 7 has long bothered me. I think it is temperature sensitive. I think it produces much higher pressure for the same volume and people are loading it volume for volume as a sub for BP.

I was going to continue the comparison with the .45-70 data in the same manual but I don't know that such comparison is constructive at this point in the discussion.

I guess it is too early in the day for a cogent thought but I did want to thank you for your contribution. Again, interesting as always.

colo native · Post by **colo native** » Mon Jan 19, 2009 8:21 am

I must say I do enjoy reading this post and look forward for more...

KirkD · Post by **KirkD** » Mon Jan 19, 2009 12:14 pm

Leverluver, you've raised an important point about breech thrust that I've been thinking about myself. A low pressure load may result in a lower hoop-stress on the chamber walls, but greater axial impact against the breech face simply because the case is not temporarily welded (sealed) to the chamber walls. It is for this reason that when I am developing a smokeless load for an original BP rifle or sixgun, I stick with powders and loads fast enough to seal the case against the wall (i.e., no sooty outsides to my cases), while still maintaining a peak pressure that is the same or slightly lower than BP for the same ballistics (i.e., bullet weight and velocity) as original BP loads. This gives me a pretty narrow band within which to work. Fast powders seal the case, but at the expense of too high a peak pressure. On the other hand, a powder that is too slow will give a nice low peak pressure, but fail to seal the case and result in a higher axial impact against the bolt. A fellow needs to stay in between these two boundaries if he is going to develop safe smokeless loads for ancient guns.

In the back of Snooky's Winchester Lever Legacy book, there is an article where the breech thrust of a 30-30 is tested under various conditions. If the outside of the case was lubed, it did not grip the chamber walls and produced more axial impact. However a standard load in a dry case required almost no bolt at all to keep it in the chamber. So in my opinion, the ideal smokeless load to replace a BP load must use powders with the same burning curve as BP for the same ballistics. You can go lower, but not so low as to get sooty cases. I think this is not only important for the '73's and the '76's, but also for the old sixguns, expecially the S&W top breaks.

Most fellows I know don't give a tinker's hoot what powder they use as long as it is a 'mild' load in their old guns. For the same velocity, Trail Boss is not a 'mild load', nor is Unique.

Bottom Line: An ideal smokeless load for an original BP gun should run within a narrow band, where the parameters basically aim for the same ballistics for the same pressure curve. This means, for the beginner, that they use powders around the DPI and RQ of Blue Dot, 2400, SR4759 and maybe IMR 4227 and 5744 and they use the same cast bullet weight and hardness (i.e., don't be using those 20 BHN Hardcast bullets and think it gives the same pressure as the 7 to 13 BHN bullets). I prefer soft cast bullets in everything but my 30-30, where 2,200 fps makes hard cast more attractive. The more advanced load developer can begin to play around with different bullet weights and different powders (i.e., increase the bullet weight, decrease the speed of the powder). I prefer, however, to stay with original ballistics in old BP guns, especially original 73's, 76's and original S&W Top breaks like the 44 Russian and 45 Schofield.

By the way, I recall seeing only one blown up '76, and it failed in the chamber area.

Mike D. · Post by **Mike D.** » Mon Jan 19, 2009 12:45 pm

Wasn't there some real time load data posted here that stated that 40-44 grns IMR 4198 gave the best results in the .45-75? I believe it was last year sometime, when all this "discussion" of the cartridge began.
The so called "safe" loads for this cartridge are too puny to even consider for serious hunting of mule deer, and certainly not elk.

KWK · Post by **KWK** » Mon Jan 19, 2009 4:00 pm

Yes, when velocities have exceeded the BP "envelope" so have pressures.

I can't agree with this statement. To get a given velocity, BP needs a charge which weighs more. This extra weight of charge is -- as far as the gases doing the pushing are concerned -- equivalent to a heavier bullet to be accelerated.

The trick is finding a smokeless with suitable burning characteristics. This is no easy task, a task made more difficult by the excess space in the case and its effect on the initial ignition of the charge.

In the back of Snooky's Winchester Lever Legacy book, there is an article where the breech thrust of a 30-30 is tested under various conditions.

Was this done with a strain gauge on the breech? Ackley claimed the brass can carry all the thrust in a .30-30, but it appears to me there just isn't enough brass to do this. There are portable oscilloscopes here in the office; I ought to glue a strain gauge to a breech and try it out.

In computing what breech thrust needs to be contained, I use the peak pressure times the OD area of the cartridge base. If a case fails near the base, the gases will be able to act on nearly the whole face of the chamber.

This computed number is too high if you're trying to estimate the service life, for the typical firing will have the brass carrying part of the load, and this increases the fatigue life of the action. British proof tests (oiled cases) found the case carried -- roughly -- about 1/4 of the total load, but even an oiled case might cling some.

KirkD · Post by **KirkD** » Mon Jan 19, 2009 6:01 pm

KWK wrote:
In the back of Snooky's Winchester Lever Legacy book, there is an article where the breech thrust of a 30-30 is tested under various conditions.
Was this done with a strain gauge on the breech? Ackley claimed the brass can carry all the thrust in a .30-30, but it appears to me there just isn't enough brass to do this.

He did better than that. He screwed out the barrel so that the base of the cartridge was unsupported. The case stayed in place, but the primer backed out the distance of the headspace. He did this for various distances of headspace and found that in that rifle, there is zero thrust on the bolt face, except for what the primer exerts.

Leverluver · Post by **Leverluver** » Mon Jan 19, 2009 11:25 pm

Kirk

Leverluver, you've raised an important point about breech thrust that I've been thinking about myself. Of course, brilliant minds often think alike

I agree with basically all you say but in a way, I wish we were both wrong but I have a sneaking suspicion that we aren't. I would prefer to come up with some good loads with slower powders that could actually be useful in the hunting field. At the start, I intend to narrow my investigations to the black powder curve equivalent smokeless powders and try the slower powders later (in a test gun, not a 76)

Also in total agreement as to Unique and Trail Boss. Best left in pistols where they belong. I'm waiting for someone to ask what load of Bullseye should he use in a 45-75

The chamber area of a 76 also gives me no great comfort. When I pulled my barrel, I had to go put on a fresh pair of Depends after I saw how thin the chamber area was, and that was in 45-60. I was starting to have serious reservations about hogging it out even more for a 45-75. There is dang little meat between the chamber wall and the bottom of the threads; a whole lots less than for a lot of weakly chambered revolvers.

BTW, I'm going to miss you on CSI

Leverluver · Post by **Leverluver** » Tue Jan 20, 2009 3:12 am

Hobie

"I was going to continue the comparison with the .45-70 data in the same manual but I don't know that such comparison is constructive at this point in the discussion."

Sorry, didn't mean to derail your hypothesis. Actually, I'm going to use the same idea when looking for places to start so I think your idea has merit. At least it has worked for me on other cartridges. Granted, I will have a safety factor of ~300% so I'm not concerned with an ooops here and there.

We'll see. Meanwhile I have to get that 49th and see what all the huff is about.

Post by **Hobie** » Tue Jan 20, 2009 8:22 am

Leverluver wrote:Hobie

"I was going to continue the comparison with the .45-70 data in the same manual but I don't know that such comparison is constructive at this point in the discussion."

Sorry, didn't mean to derail your hypothesis. Actually, I'm going to use the same idea when looking for places to start so I think your idea has merit. At least it has worked for me on other cartridges. Granted, I will have a safety factor of ~300% so I'm not concerned with an ooops here and there.

We'll see. Meanwhile I have to get that 49th and see what all the huff is about.

You didn't derail it. I just think that the discussion took another turn...

No problem there. It happens and makes life interesting. I was interested that there are often WIDE differences in charge weights with the same bullet. E.g. with 457122 and IMR 4198, the max in the .45-70 is 38 gr. for 1595 fps and 15,100 CUP but just 26 gr. for 1310 fps in the .45-75 (no pressure given). Perhaps someone can explain to me why a strain gauge couldn't be applied to a 1876 and some data recorded. I'm ignorant on the technical aspects that might or might not prevent such. I don't like being ignorant!

Leverluver · Post by **Leverluver** » Tue Jan 20, 2009 10:20 am

It can; just keep your shorts on

kimwcook · Post by **kimwcook** » Tue Jan 20, 2009 11:11 am

This is getting really interesting.

Post by **Hobie** » Tue Jan 20, 2009 12:05 pm

Well, then the esteemed (and I am NOT being sarcastic here) Buck Elliott in commenting about his Uberti 1873 says:

No, you can't hot-rod a '73, like you could a '92, but SO WHAT...?!?

With 23 gr H-4198 and a 250 gr. LaserCast slug, I get right at 1400 fps. That is equal to pretty good .44 Mag ballistics from a revolver.

Different bullet weights, case capacity and all, I still think this is interesting.