Last week I took delivery of an original S&W Schofield shipped in 1876 for use by the US Cavalry (see http://www.canadiangunnutz.com/forum/showthread.php?t=183643&page=19 for the first photo and a brief write-up). Here's another 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 black powder. 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)
NOTE: The original Scofield has a tight throat. For this reason, I strongly suggest you use only soft cast or pure lead bullets. Do not use hardcast. The increased pressure in ramming a hardcast bullet through the narrow throat could increase pressures.
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 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 (O.A.L.=1.389)
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 substituted 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". 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.
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 black powder. 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)
NOTE: The original Scofield has a tight throat. For this reason, I strongly suggest you use only soft cast or pure lead bullets. Do not use hardcast. The increased pressure in ramming a hardcast bullet through the narrow throat could increase pressures.
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 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 (O.A.L.=1.389)
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 substituted 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". 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.
Last edited:
