OT: Load development for original Schofield Sixgun

[KirkD]

Last week I took delivery of an original S&W Schofield shipped in 1876 for use by the US Cavalry. Here's a photo:



I don't plan to do a lot of shooting with this old vintage six-gun, but I do want to do some on special occasions, so I set about to develop a low-pressure smokeless load that would give me roughly the same velocities as Mike Venturino's black powder loads published in Shooting Sixguns of the Old West. I have a copy of an 1896 Winchester catalogue that listed their 45 S&W load as 30 grains of black powder under a 250 grain bullet.

My basic rules for developing a black powder pistol load are as follows:

1. Always use powders slower than 2400 (powders slower than 2400 will give a lower peak pressure than black powder for the same velocity)
2. Stay at or under original black powder velocities
3. Aim for a capacity load, slightly compressed to keep burning consistent and E.S. and S.D. similar to black powder loads.

Brass: Starline 45 Schofield
Bullets: 250 grain cast RNFP from Wolf Bullets sized .452 (about .002 undersize to my bore)


For powders, I thought I'd try IMR 3031 and IMR 4198. Sherman Bell has shown in two published articles that IMR 4198 gives lower peak pressures than black powder. He also has one article showing that IMR 3031 gives even lower peak pressures than either black powder of IMR 4198.

IMR 3031
I figured I'd start with the slower of the two powders. I loaded up just one round, stepped into the back yard, and fired it across my Chrony, then adjusted upwards. Here are the results:

15 grains .. 298 fps (bullet made a 1/4" dent in the green Elm stump and bounced off
17 grains .. 405 fps
19 grains .. 536 fps
21 grains .. 615 (this filled the case to capacity and was slightly compressed)

I had maxxed out and it was clear that there was no way I'd be able to get anywhere near enough 3031 into the case for 800 fps so obviously 3031 was too slow. I then moved to IMR 4198.

IMR 4198

I used the same procedure as before, except as I drew closer to the target velocity of 800 fps, I started firing 5 rounds across the Chrony for each load (instead of just one) to get an idea of extreme spread (E.S.) and standard deviation (S.D.). Here are the results for an O.A.L. of 1.399:

15 grains .. 518 fps
16 grains .. 613 fps
17 grains .. 698 fps
18 grains .. 716 fps
18.6 grains .. 776 fps, E.S.=62 fps
18.8 grains .. 791 fps, E.S.=47 fps, S.D.=17 fps
19.1 grains .. 780 fps, E.S.=66 fps, S.D.=27 fps (18.9 grains by other measure ... see note about the accuracy of my scales at end of report)
19.2 grains .. 787 fps, E.S.=70 fps, S.D.=25 fps

At this point, I was near capacity but not compressed. I was not happy with the E.S. and S.D. As far as I was concerned, they were too high. I needed a slightly compressed load to solve this problem. There were two ways to do it; increase the powder or decrease the O.A.L. (seating the bullet slightly deeper to compress the powder). Since I was near the velocity I wanted, adding more powder was really not an option, so I decided to seat the bullet 0.010" deeper to the upper edge of the crimping groove. This did the job, as you can see from the results below:

19.1 grains .. 773 fps, E.S.=20 fps, S.D.=7 fps (O.A.L.=1.389)
19.2 grains .. 793 fps, E.S.=30 fps, S.D.=12 fps "

For comparison, a similar black powder load published by Mike Venturino in Shooting Sixguns of the Old West gives the following results for FFFg

27 grains .. 805 fps, E.S.=35 fps. with a 239 grain cast bullet.

I tried 19.3 grains but didn't get the full 5 shots to register on the chrony, but of the three shots that did, I got a velocity of 811 fps with an E.S. of about 25 fps.

I'm a pretty conservative fellow, so I decided that I would settle on 19.1 grains of IMR 4198 for 773 fps.

Finally, it was time to see how this load shot. I decided to shoot at 50 feet so that I could compare the 5-shot group with Mike Venturino's published group for his FFFg load cited above. I rested the sixshooter on a bag of bird seed on a picnic table in the backyard. A bag of bird seed is a poor substitute for a sandbag ... way too mushy. Furthermore, I'm a pretty poor pistol shot. I got a 5-shot group at 50 feet of exactly 4". I'm sure that with a proper size bullet (these are .002 undersize) and a decent sandbag to rest the pistol on instead of the mushy birdseed, I'd get a significantly better group. For comparison with Venturino's load cited above, he did three groups of 5 shots each and got 5.5", 4.13", and 4.75", so it looks like my load is alright and compares favourably with black powder in velocity, E.S. and group size. However, my peak pressure is lower, with the result that the pressure isn't even enough to expand the Starline brass to seal against the chamber walls. The result is that soot leaks back along the sides of the case. However, I'll take dirty brass in exchange for a nice low peak pressure in this classic old gun. Here's a photo of the target:



Note: I only have a balance beam mechanical powder scales. Between 18.9 and 19.0, I noticed that there is a 0.2 grain discrepancy, with 18.9 = 19.1 when the transition is made. This is another good reason to work up your load and not start at the max. Your scale may not give the same reading as mine.

[Ben_Rumson]

Nice work Kirk & nice pistola... I'd wager if you annealed the brass your velocity would go up a tad & accuracy would improve.

[KirkD]

That's a good idea, Ben. The annealed brass would be a bit softer and might seal against the chamber walls a bit better.

[Hanz]

Congrats on the S&W and finding a good load to use in it. That's one beautiful Schofield.

Best of luck with it,

Doug

[Ysabel Kid]

Great post Kirk! Mind if I rip off your recipes?!?

[KirkD]

Great post Kirk! Mind if I rip off your recipes?!?

Feel free, but it goes with the usual disclaimer that your powder scales, bullets, etc, may be slightly different, so I'd recommend starting off on the low side of things. I'm sure you know this, but I say it for the benefit of others who may not be as knowledgeable. There are very good reasons for starting low and carefully working up.

[Ysabel Kid]

Great post Kirk! Mind if I rip off your recipes?!?

Feel free, but it goes with the usual disclaimer that your powder scales, bullets, etc, may be slightly different, so I'd recommend starting off on the low side of things. I'm sure you know this, but I say it for the benefit of others who may not be as knowledgeable. There are very good reasons for starting low and carefully working up.

Kirk, I'd be disappointed if you didn't make the disclaimer. One of the reasons I trust your loads and have used them with great success!!!

Thanks!!!

Jay

[JerryB]

Kirk,thanks for the report. Its good to see great minds working for something useful to folks like us.

Jerry

[20cows]

It looks like you are well down the road to success!

[20cows]

Kirk, I was discussing your load work with a friend and we both were wondering why, if you can get this kind of performance, near 800 fps, why it was not more commonly done, particularly with older black powder guns.

I think I would really like to try this in my 45 Colt SAA. Would it be reasonable to try one of the similar speed spherical powders for their metering properties?

What do you think?

[KirkD]

Kirk, I was discussing your load work with a friend and we both were wondering why, if you can get this kind of performance, near 800 fps, why it was not more commonly done, particularly with older black powder guns.

I think I would really like to try this in my 45 Colt SAA. Would it be reasonable to try one of the similar speed spherical powders for their metering properties?

What do you think?

In answer to your first question, I'm not sure, but I can hazard an educated guess based on some of the comments people have made to me in the past. Among those who reload, many don't really understand how to control pressure and extreme spread probably because they use published data and simply do not need to worry about such things. Furthermore, most pistol data nowadays seem to use fast 'pistol' powders that give a much higher peak pressure than black powder does for the same velocity. As a result, pistol powders can be very unsafe to use in an antique pistol unless one really drops the load amount/pressure/velocity. Furthermore, with the fast pistol powders, a typical load is only a fraction of the case capacity. Just one accidental double charge, and it is game over for your antique pistol. Bottom line, there are a lot of warnings out there against using smokeless powders in antique pistols and they are well worth heeding unless you really understand how to control pressure and extreme spread.

With regard to your second question, what powder did you have in mind? When I begin to develop a smokeless load for an antique black powder cartridge, here are my rules:

1. Never use a powder faster than 2400 (in the chart of burning speeds, black powder falls into approximately the Blue Dot/2400 range of powders. Any powder faster than that will develop peak pressures higher than black powder for the same velocity.
2. Aim for capacity loads, very slightly compressed. Reason: if you have a smokeless load that gives the same velocity as the black powder load but at a lower peak pressure, but you also have an extreme spread of 200 fps, you can still exceed what your pistol was designed to handle whenever you get one of those rounds that are at the upper extreme for that load. For this reason, you want to keep your extreme spread very small, at or less than what black powder would give. The best way to accomplish this is to go for a capacity load that is slightly compressed so that burning occurs with maximum consistency, which is the same reason why good black powder loads have such a low extreme spread. That will mean that not only is your powder slower than 2400, it is probably significantly slower, the larger the case capacity of the cartridge. The bonus is that it is impossible to double charge your cases, so you eliminate that danger.
3. Use a soft cast or pure lead bullet. Vintage pistols did not use hardcast bullets. A hard cast bullet is harder to ram through the forcing cone, which will cause a pressure spike regardless of whether you use black powder or smokeless. Use soft cast bullet or, my preference, pure lead. A pure lead bullet cannot lead your bore at the sub-1000 fps velocities you have with antique handguns (unless, perhaps, you have seriously pitted barrel that is scrapping the lead off your bullet and allowing all sorts of high-pressure blow-by).

I find that the larger the case capacity, the slower the powder is required for a capacity load. So for my 44 Russian, my capacity load requires 5744 (IMR 4227 would probably work as well). For my 45 Schofield, IMR 4198 is required, for a 45 Colt, you would probably have to go with a powder a bit slower than 4198. The case capacity pretty much dictates which powder you will have to use for capacity loads that match original black powder velocities. The trick is to find that powder. If I were to develop a smokeless capacity load for the 45 Colt, I'd probably start with IMR 3031. Of course, you never, ever start with a capacity load. Start with a really light load. You will notice that my first load of IMR 3031 gave only 231 fps.

I've not tried slow, spherical powders, but they may meter more accurately. Which powder did you have in mind?

[20cows]

Off the top of my head (I'm not where I can consult burn rate tables at the moment), I have H380, H414 (I think) and IMR 4227(it may be faster than you're talking, but no chart here).

I am using the 4227 for a trapper 38-55 load that is more or less black powder equivalent. (~1400fps w/ 275 gr bullet)

[Hobie]

I would just like to point out that black powder equivalent velocities don't necessarily give black powder equivalent pressures.

Kirk,

Isn't there a formula for converting BP charges to IMR/H-4198 charges?

[20cows]

Hoby, I agree that 4227 would be more of a "magnum" load than I'm looking for in my 45 SAA

[J Miller]

I'm interested in type of load for the .45 Colt as well. But from what little I've used 4227 isn't the powder to use. I think Hornady shows 23.x grains with their 250gr XTP HP as cranking out around 1200+ fps. This is OK for that load, but it isn't a capacity load, and the pressure is way over what a black powder gun could handle.

Joe

[20cows]

I just looked at a burn rate chart on line and according to it, I may not have a spherical powder that would be appropriate. I'm trying to remember what I've got (some was bought and tried YEARS ago for load development in a rifle and then set asside when I settled on something else).

I think I have Reloader 7, IMR 3031, maybe H335, IMR 4895, IMR 4064, Win 748, H380(?), H414, and IMR 4350.

[marlinman93]

Kirk,
What a great looking Smith, nd a great report to go along with it! Those old Schofields just feel great, and balance so nicely!

[20cows]

Kirk, I have now had a chance to look at a table and check my inventory. The powders I have on hand that are slower than 4198 are IMR 3031, H335, IMR 4895, Win 748 and IMR 4350.

The H335 may be the one to start with. It's slower than 3031 and it is a ball powder. It may be too slow, but we'll see....


Thanks Kirk!

[KirkD]

I would just like to point out that black powder equivalent velocities don't necessarily give black powder equivalent pressures.

Kirk,

Isn't there a formula for converting BP charges to IMR/H-4198 charges?

Hobie is right. Black powder equivalent velocities with Bullseye is a recipe for hand-held, antique shrapnel. The only powders that will give you roughly black powder peak pressures with black powder velocities are those right around 2400. However, in my experience, 2400 is prone to high extreme spreads, which is why I prefer slower powders that fill the case. In general, for the same black powder velocities, powders faster than 2400 will give higher peak pressures than BP and powders slower than 2400 will give lower peak pressures than BP.

In my load development using both IMR 4227 and Accurate 5744, I found that they gave identical ballistics in the 38-55. They are right next to each other on the burn rate tables.

As for a formula for converting black powder loads to IMR 4198 loads, I believe Sherman Bell gave one in his article. It is an approximation, and I always prefer to develop my own loads, putting each change over a Chrony.

In general, for powders slower than 2400, if you want a capacity load, slightly compressed, that matches original BP velocities, I've found that the larger the case capacity, the slower the powder you will have to use in order to accomplish a capacity load, slightly compressed. Note: this general rule of thumb works only for cartridges that were originally BP cartridges. (i.e., the rule works for 45 Colt, but not 30-30). So if the 45 Schofield requires IMR 4198 for a capacity load, slightly compressed, the 45 Colt, with its slightly larger case capacity, may require a powder slightly slower than IMR 4198 in order to achieve a capacity load, slightly compressed, that matches original BP velocities.

Hope this makes sense. In general, if you are developing a smokeless load for a cartridge that was originally BP, if you follow the following three rules, you should be alright:

1. Use smokeless powders slower than 2400
2. Stay at or under original BP velocities.
3. Keep your extreme spread down by aiming for capacity loads
4. Start low and work up, checking the chrony with each step to make sure you are not exceeding BP velocities.
5. Stay away from powders faster than 2400 for BP cartridges. If you insist on using Unique, you'll have to reduce the velocity below BP velocities and, even then, I have no idea what your peak pressure will be. There are published loads that use Unique. Hopefully, those loads have been pressure tested and are safe. I just don't like them (except, of course, in modern pistol cartridges .... I use Unique for my 45 ACP).