'73 '76 action strength

[firefuzz]

Hi folks, long time no be here. Hope everyone is doing good.

Several years ago their was a discussion about the strength of the '73/'76 action strength and someone posted a link to an article on Winchester having fired one of these rifles with one toggle link removed with proof loads. Does anyone remember what I talking about and maybe have a link to that article. I thought i had saved it but evidently not.

Thanks,
Rob

[gamekeeper]

The strength of the Model 1876 rifle and the .45-75 W.C.F. cartridge was tested by Winchester in the late 1870s. The factory conducted tests on the strength and reliability of the action to answer concerns by customers. These tests will astound collectors and shooters who have stated the Model 1876's toggle link action is "weak." In response to a letter sent to the company by Charles Hallock, Esquire, of Forest & Stream magazine, Oliver Winchester responded by telling about the tests the factory accomplished on the 1876 rifle. He indicated that engineers first started the tests by removing one of the toggle links and fired 20 rounds (this was with .45-75 W.C.F. cartridge with 350 grain bullet) with no effect. They restored the missing link then went through 6 more trials starting with a charge of 105 grains of black powder, behind a 700 grain bullet! The comment "worked well" is noted. They then increased the charge of powder to 165 grains behind 3 bullets (1,150 grains) and that "worked well." From there, they increased the powder charge to 203 grains and added more bullets until they reached 1,750 grains of lead (five 350 grain bullets). This also "worked well." Finally, they added one more bullet, bringing the total weight to 2,100 grains, and things began to happen. The comment was, "Breech pin slightly bent. Arm working stiff." The seventh and final test was again 203 grains of powder but this time six Martini bullets weighing 480 grains each (2,880 grains) were used. "The charge bent the breech pin, blew out the side plates, split the frame and otherwise disabled the arm," was the comment. Oliver Winchester noted that in this seventh trial, the shell had burst into fragments and the escape of gas at the breech did the damage.

Hobie posted this a few years back.

[barbarossa]

Uberti did produce their 73 rifle in 44mag though the metallurgy is different from the originals but the design of the action is the same.

[black river smith]

Well I went looking and found this posting: viewtopic.php?t=88301

Well it did have what you asked about ......... but now the photos of the text describing the procedure that Winchester used to damage the 1876 is now missing.

But that is maybe what you remember or maybe you are looking for something older. Sorry.

BRS

PS -- The same information was posted on CAS City, so I went and checked but again the text photo's are gone.

[hpbear101]

https://www.youtube.com/watch?v=Iazh2CGiY_s&t=951s

I don't have a print link to the study you refer too, but here is a video link of Mark from the Cinnabar covering it in detail.

[Pat C]

Only thing I heard was the 1876 would not handle the 45-70 heavy bullet .So they settled with 45-75 and a lighter bullet

[veeman]

The 76 receiver is not long enough for the 45/70, so they simply shortened it to a bottle neck round. Bullets much heavier than 375 grains don't stabilize well and will keyhole. A 45/75 with a full case of FF Black Powder is nothing to sneeze at to be sure. It will kill anything on this continent just as easily as it did 145 years ago. The modern Uberti 76's metallurgy is much stronger now than it was back in the day, but no need to hotrod it.

[COSteve]

I talked to Steve of Steve's Gunz at length in early 2013 before I got my Uberti '73 in .45 Colt about the design and strength of their actions. I was concerned about the bolt thrust of the standard pressure .45 Colt round. I made up a chart after I talked to him on this and it clearly shows that the bolt thrust of modern cartridges exceed that of the cartridges the rifle was originally designed around.

1873 Levergun Bolt Thrust.jpg

He said that while the absolute strength of the '73's toggle link action is enough to handle the load of the cartridges it was designed for, his issue he saw was that the toggle link pins couldn elongate the holes in the links over time with high pressure loads.

That can lead to a loose lockup of the action causing an unsafe condition. In addition, he also said he had seen actions where the frame had stretched just a bit but enough to also cause a weak lockup of the action.

I'd love for him to respond to this topic himself and give his first hand experiences on this subject as I might have not explained what he told me exactly and after all, he's the expert having worked on hundreds of the rifles.

[Malamute]

I talked to Steve of Steve's Gunz at length in early 2013 before I got my Uberti '73 in .45 Colt about the design and strength of their actions. I was concerned about the bolt thrust of the standard pressure .45 Colt round. I made up a chart after I talked to him on this and it clearly shows that the bolt thrust of modern cartridges exceed that of the cartridges the rifle was originally designed around.

1873 Levergun Bolt Thrust.jpg

He said that while the absolute strength of the '73's toggle link action is enough to handle the load of the cartridges it was designed for, his issue he saw was that the toggle link pins couldn elongate the holes in the links over time with high pressure loads.

That can lead to a loose lockup of the action causing an unsafe condition. In addition, he also said he had seen actions where the frame had stretched just a bit but enough to also cause a weak lockup of the action.

I'd love for him to respond to this topic himself and give his first hand experiences on this subject as I might have not explained what he told me exactly and after all, he's the expert having worked on hundreds of the rifles.

To expand on Steves post a bit, ^^^ I recall it coming up that accelerated wear over time was one of the main issues with higher pressure loads, and Steve of Steves Gunz (and others) had rebuilt guns that had loosened up. As the parts loosen, the tolerances open up, causing faster wear. The links can be replaced with oversize ones, or the existing parts I believe can be set up and machined for slightly larger pins and done in a way that tightens up the fit. The barrel could also be set back a turn and rechambered, which does a similar thing on the firing end, but once unlocked the looser tolerance remains. I dont know how much of an issue that would be.

Ive contaced Steve of Steves Gunz about the brass frame guns in 45 Colt and longevity, the main point he mentioned was yes, over time with lots of use they will start to loosen up, but the ones he was mainly seeing for repair/tighening up were ones used with heavier than normal loads. I believe hes also mentioned that the 357 guns used with lots of magnum loads tend to loosen up faster than other chamberings, but not to an alarming degree. The cost of enough ammo to cause that far exceeds the cost to repair, something to keep in mind in any of this.

When the strength question comes up, keep in mind the end result isnt "the bolt blows back in your face" as some seem to think, its loosening of the gun, which can cause functioning problems. Blowing the bottom of the chamber/barrel out seems to be the common catastrophic failure point in most lever actions, regardless of action type.

In asking about some time ago, one instance of the firing pin blowing back was mentioned from someone that had seen it firsthand. I dont recall the diagnosis of the cause, it may have been a case failure. The bolt itself is contained within the frame, only the firing pin extension can come out the back of the frame in normal use or potentially in some catastrophic (but rare) failure.

A total seat of the pants guess, but I think more revolvers come apart catastrophically than 73s or 66s.

[Nath]

I've said this many many times.

Bolt thrust is NOT exerted on the bolt to the level the calculation implies.
The calculated bolt thrust figure does not recognise the fact that the cartridge momentarily grips the chamber at peak pressure.
Only after peak pressure does the case set back against the breech mechanism.

It is quite possible that low pressure ammunition such as cowboy action shooting load do in fact expert more bolt thrust or percussion on the mechanism due to the pressure not being high enough for the case to grip the chamber etc!

[COSteve]

Nath, consider what you just said. You said that the case expands to tightly grip the chamber walls. If that's true, and it is, then the base of the case can also stretch allowing the base of the case to thrust against the bolt face.

All of us reloaders who reload necked rifle calibers know about the warning of repeated reloading can lead to a case separation down at the base because of thinning of the case from the base stretching as the base thrusts against the bolt face.

[black river smith]

I have finally found a text copy of the missing photo. Sorry it took me awhile to get back to this.

Not saying where I found it -- but here is the Winchester testing summary for the 1876 rifle.

I don't know how many of you fellers have read this, but this excerpt from Bill Hockett's 2002 article on the Centennial Winchester explains the strength testing that Winchester performed on the new model. it is a bit of am eye opener.

"The Model 1876 is the only repeating rifle that had successful, documented use in the northern plains buffalo slaughter. Earlier repeating rifles such as the Henry, Spencer, and Winchester Models of 1866 and 1873 may have seen limited use, but only the Model 1876 was considered by hunters as powerful enough to do the job against the big woolies. The strength of the Model 1876 rifle and the .45-75 W.C.F. cartridge was tested by Winchester in the late 1870s. The factory conducted tests on the strength and reliability of the action to answer concerns by customers. These tests will astound collectors and shooters who have stated the Model 1876's toggle link action is "weak." In response to a letter sent to the company by Charles Hallock, Esquire, of Forest & Stream magazine, Oliver Winchester responded by telling about the tests the factory accomplished on the 1876 rifle. He indicated that engineers first started the tests by removing one of the toggle links and fired 20 rounds (this was with .45-75 W.C.F. cartridge with 350 grain bullet) with no effect. They restored the missing link then went through 6 more trials starting with a charge of 105 grains of black powder, behind a 700 grain bullet! The comment "worked well" is noted. They then increased the charge of powder to 165 grains behind 3 bullets (1,150 grains) and that "worked well." From there, they increased the powder charge to 203 grains and added more bullets until they reached 1,750 grains of lead (five 350 grain bullets). This also "worked well." Finally, they added one more bullet, bringing the total weight to 2,100 grains, and things began to happen. The comment was, "Breech pin slightly bent. Arm working stiff." The seventh and final test was again 203 grains of powder but this time six Martini bullets weighing 480 grains each (2,880 grains) were used. "The charge bent the breech pin, blew out the side plates, split the frame and otherwise disabled the arm," was the comment. Oliver Winchester noted that in this seventh trial, the shell had burst into fragments and the escape of gas at the breech did the damage."

Here is another version of the text from a different website.

Here's a verbatim portion of Hockett's research:

FACTS: The Model 1876 is the only repeating rifle that had successful, documented use in the northern plains buffalo slaughter. Earlier repeating rifles such as the Henry, Spencer, and Winchester Models of 1866 and 1873 may have seen limited use, but only the Model 1876 was considered by hunters as powerful enough to do the job against the big woolies. The strength of the Model 1876 rifle and the .45-75 W.C.F. cartridge was tested by Winchester in the late 1870s. The factory conducted tests on the strength and reliability of the action to answer concerns by customers. These tests will astound collectors and shooters who have stated the Model 1876's toggle link action is "weak." In response to a letter sent to the company by Charles Hallock, Esquire, of Forest & Stream magazine, Oliver Winchester responded by telling about the tests the factory accomplished on the 1876 rifle. He indicated that engineers first started the tests by removing one of the toggle links and fired 20 rounds (this was with .45-75 W.C.F. cartridge with 350 grain bullet) with no effect. They restored the missing link then went through 6 more trials starting with a charge of 105 grains of black powder, behind a 700 grain bullet! The comment "worked well" is noted. They then increased the charge of powder to 165 grains behind 3 bullets (1,150 grains) and that "worked well." From there, they increased the powder charge to 203 grains and added more bullets until they reached 1,750 grains of lead (five 350 grain bullets). This also "worked well." Finally, they added one more bullet, bringing the total weight to 2,100 grains, and things began to happen. The comment was, "Breech pin slightly bent. Arm working stiff." The seventh and final test was again 203 grains of powder but this time six Martini bullets weighing 480 grains each (2,880 grains) were used. "The charge bent the breech pin, blew out the side plates, split the frame and otherwise disabled the arm," was the comment. Oliver Winchester noted that in this seventh trial, the shell had burst into fragments and the escape of gas at the breech did the damage.
The big Centennial model was known for its excellent accuracy and is reputed to have been the most finely made of all the early Winchester lever action rifles.

[Nath]

Nath, consider what you just said. You said that the case expands to tightly grip the chamber walls. If that's true, and it is, then the base of the case can also stretch allowing the base of the case to thrust against the bolt face.

All of us reloaders who reload necked rifle calibers know about the warning of repeated reloading can lead to a case separation down at the base because of thinning of the case from the base stretching as the base thrusts against the bolt face.

Aye, but not the total sum of peak pressure.

For instance. It is quite possible to load a rifle cartridge beyond service pressure by a substantial amount and end up struggling to open the action.
Now , under those circumstances we are getting bolt thrust, so much so everything is locked up. Or close to locking up.
The very fact that an action can be opened is demonstrative that not all pressure is being exerted on the mechanism.
Some automatics depend on it!

I will concede though that I honestly believe low powered ammunition experts not necessarily more thrust but more percussion on the mechanism based purely on my assumption that the case, depending on which one and type does not grip the chamber sufficiently.
That is why I believe that in the cowboy action shooting world they have experienced some action loosening.

[COSteve]

I don't think it matters if it's the total pressure or just partial pressure because if the percentage of thrust transferred to the action via the bolt is roughly the same on the various calibers, then it's a fact that the newer calibers are exerting a significantly higher thrust on the bolt and therefore on the action. That means that the pins in the holes and seeing increase pressure that will over time lead to an elongation of the hole. It doesn't matter the absolute number of lbs but rather the increase vs the original thrust the action was designed for. It's mechanics and the ability of the hole to resist deforming.

I can also see the toggle link pins elongating the holes just by the repeated cycling of the action over a long time. As the design depends upon the overall length of the 2 links to hold the bolt fully closed, any slop in the pins in the holes will by definition allow for a loosening of the action. Even with a standard pressure .45 Colt at 14,000psi, that's enough to cause problems if the action is locked up tight.

[Nath]

We will have to agree to disagree my friend.
There are an aweful lot of original Winchesters out there still tight my friend.
All the best.

[COSteve]

I don't think we actually disagree. After talking to Steve I did get the .45 Colt Uberti rifle and later got a .45 Colt Uberti 'Yellowboy' carbine. I stick to standard pressure loads for both and think that absent wearing them out with ammo, they'll do just fine.

My concern is with those who choose to shoot full power .357mag or .44mag through theirs as that's where, over time, one might see some loosening up of the actions. If one stays with standard pressure loads it's unlikely in my mind that anyone could afford to shoot enough to cause a problem, however, some of those CASS folks do run up the round count pretty high.