So, I bought a new gun last week. A 45-70, from Harrington Richardson. 
This is a single-shot break action rifle, modelled after the original Frank Wesson rifles of 1860. It has a medium heavy 32" barrel, and weighs 8lbs. It comes with a Williams rear peep sight, and a Lyman #17 front hooded globe sight. This rifle uses the NEF SB2 action, also used for such high-intensity cartridges as the 308 winchester, at over 60000psi.
Given that the action was OK for very high pressures, and the experiences of the guys over at the graybeardoutdoors forums, I knew this was safe with the stout levergun and even ruger #1 loads published for the 45-70. I was planning on shooting cast, so I figured it'd be best if I shot heavier weights so as to limit the velocity, to prevent leading. I found a box of bullet barn 405 gr bullets at P&D, which I bought. I e-mailed bullet barn to see if the could offer any guidance as to how I should load these, and they responded that they had had no problems loading to ~1650fps in a micro-grooved Marlin guide gun. OK, cool, I figured I would use load data for about that speed, and suspected I'd gain another hundred fps or so given the 32" barrel on my gun vs the 18.5" barrel on the guide gun. Guys have loaded up to 2100fps in this gun over on the other forums, so I was well within operating limits aiming at 1750.
I looked through my powder cabinet, and selected some surplus WC-735 powder as the most suitable powder on hand. This powder is supposedly in the neighbourhood of H335, maybe 5% faster. The information that I had suggested that I approach the minimum 335 loads as the maximum for this powder. Most sources quote 52 grains 335 as the minimum 'lever-gun' load for 335, at about 1600fps with the 405 gr bullets (with an 18.5" barrel). As I was targeting 1750 fps with a slightly faster powder and a longer barrel, I loaded a few at 50.0 grains, 51.0 grains and 52.0 grains. I seated the bullets just off the lands, which ended up being quite far out of the case, nowhere the cannelure for the crimp. This is a single shot gun, so I didn't bother crimping.
This load was based on a number of guesses upon guesses, and I had no idea what to expect from these loads. I'd estimated somewhere between 1500fps - because I'd seated the bullets so far out, I'd increased the capacity of the cartridge quite a bit, and thought the pressures might be quite low - and 2000fps. In any case, I wasn't worried that the loads were unsafe.
I took the rifle and the loads with me today as I was headin out shootin gophers. I also happened to have my chrony with me, more by co-incidence than design. I was somewhat apprehensive of recoil - the buttplate is just a sheet of steel fastened to the end of the stock. I fired off a quick shot to see, and was surprised how manageable the kick actually was - I suspected that my loads were indeed on the low end of the spectrum. The primer on the spent casing looked perfect - (very) slight flattening, perhaps - like you get on pretty much any cartridge. Stepping up to the 52gr loads, more flattening is observable, but still not anywhere into the danger zone. The flattening at this point resembles typical medium-hot factory loads for most cartridges.
I unpacked the chrony and set it up on a fencepost, and aimed over it into a hill on the other side. I touched off a round, and looked down at the screen. 1958fps!!! Damn, that CAN'T be right. BOOM! Shot 2. 1927fps. Damn! This thing was putting out just under 3500fpe of muzzle energy! I decided that was enough, and did not chrony the 51 and 52gr loads. Having heard how hard these stout 45-70 loads can hit you, I'd expected a lot worse recoil. Folks on the graybeard forums are talking about putting lead-filled pipes into the stocks, or mercury recoil suppressors in to tame the recoil on this 8lb gun and its nasty steel buttplate. I had no problems at all with it (shooting offhand.)
Anyway, I figure that the 32" barrel contributes to the higher speeds, especially when coupled with the slightly slower burning WC-735 (most 45-70 loads seem to favour 3031, 4198, and the like). Further, I strongly suspect that the 735 surplus is a very progressive-burning powder, which also allows it to capitalize on the long barrel, and maintain a flatter pressure curve. I also noticed a slight black colour in the smoke cloud when I shot, unlike the faint gray colour typical of smokeless powders. I suspect that WC-735 also has some sort of anti-fouling agent in it, or maybe a flash suppressant, neither of which would be uncommon in mil-spec powder. After the 5 shots I put through it in total, I see zero leading - as expected from these extremely hard cast bullets and their high-speed lube.
I look forward to shooting this beauty at the range; maybe tomorrow. I'll keep y'all posted.
This is a single-shot break action rifle, modelled after the original Frank Wesson rifles of 1860. It has a medium heavy 32" barrel, and weighs 8lbs. It comes with a Williams rear peep sight, and a Lyman #17 front hooded globe sight. This rifle uses the NEF SB2 action, also used for such high-intensity cartridges as the 308 winchester, at over 60000psi.
Given that the action was OK for very high pressures, and the experiences of the guys over at the graybeardoutdoors forums, I knew this was safe with the stout levergun and even ruger #1 loads published for the 45-70. I was planning on shooting cast, so I figured it'd be best if I shot heavier weights so as to limit the velocity, to prevent leading. I found a box of bullet barn 405 gr bullets at P&D, which I bought. I e-mailed bullet barn to see if the could offer any guidance as to how I should load these, and they responded that they had had no problems loading to ~1650fps in a micro-grooved Marlin guide gun. OK, cool, I figured I would use load data for about that speed, and suspected I'd gain another hundred fps or so given the 32" barrel on my gun vs the 18.5" barrel on the guide gun. Guys have loaded up to 2100fps in this gun over on the other forums, so I was well within operating limits aiming at 1750.
I looked through my powder cabinet, and selected some surplus WC-735 powder as the most suitable powder on hand. This powder is supposedly in the neighbourhood of H335, maybe 5% faster. The information that I had suggested that I approach the minimum 335 loads as the maximum for this powder. Most sources quote 52 grains 335 as the minimum 'lever-gun' load for 335, at about 1600fps with the 405 gr bullets (with an 18.5" barrel). As I was targeting 1750 fps with a slightly faster powder and a longer barrel, I loaded a few at 50.0 grains, 51.0 grains and 52.0 grains. I seated the bullets just off the lands, which ended up being quite far out of the case, nowhere the cannelure for the crimp. This is a single shot gun, so I didn't bother crimping.
This load was based on a number of guesses upon guesses, and I had no idea what to expect from these loads. I'd estimated somewhere between 1500fps - because I'd seated the bullets so far out, I'd increased the capacity of the cartridge quite a bit, and thought the pressures might be quite low - and 2000fps. In any case, I wasn't worried that the loads were unsafe.
I took the rifle and the loads with me today as I was headin out shootin gophers. I also happened to have my chrony with me, more by co-incidence than design. I was somewhat apprehensive of recoil - the buttplate is just a sheet of steel fastened to the end of the stock. I fired off a quick shot to see, and was surprised how manageable the kick actually was - I suspected that my loads were indeed on the low end of the spectrum. The primer on the spent casing looked perfect - (very) slight flattening, perhaps - like you get on pretty much any cartridge. Stepping up to the 52gr loads, more flattening is observable, but still not anywhere into the danger zone. The flattening at this point resembles typical medium-hot factory loads for most cartridges.
I unpacked the chrony and set it up on a fencepost, and aimed over it into a hill on the other side. I touched off a round, and looked down at the screen. 1958fps!!! Damn, that CAN'T be right. BOOM! Shot 2. 1927fps. Damn! This thing was putting out just under 3500fpe of muzzle energy! I decided that was enough, and did not chrony the 51 and 52gr loads. Having heard how hard these stout 45-70 loads can hit you, I'd expected a lot worse recoil. Folks on the graybeard forums are talking about putting lead-filled pipes into the stocks, or mercury recoil suppressors in to tame the recoil on this 8lb gun and its nasty steel buttplate. I had no problems at all with it (shooting offhand.)
Anyway, I figure that the 32" barrel contributes to the higher speeds, especially when coupled with the slightly slower burning WC-735 (most 45-70 loads seem to favour 3031, 4198, and the like). Further, I strongly suspect that the 735 surplus is a very progressive-burning powder, which also allows it to capitalize on the long barrel, and maintain a flatter pressure curve. I also noticed a slight black colour in the smoke cloud when I shot, unlike the faint gray colour typical of smokeless powders. I suspect that WC-735 also has some sort of anti-fouling agent in it, or maybe a flash suppressant, neither of which would be uncommon in mil-spec powder. After the 5 shots I put through it in total, I see zero leading - as expected from these extremely hard cast bullets and their high-speed lube.
I look forward to shooting this beauty at the range; maybe tomorrow. I'll keep y'all posted.
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