For the past few months, I've intermittently experimented with using H-4198 as a reduced charge propellant in 8x56R. It and it's competitor product,
IMR 4198 have the same burning rate and are interchangeable for the data listed below.
I like 4198 and have used it for years in reduced charge loads for milsurp centerfire cartridges, full charge loads for .222 Rem. and .223 Rem., and for medium charge loads in .45-70. I also used it in my .375 Win. when I was loading for that caliber. All around, it's been a very helpful propellant for me. For this reason, I decided I would give it a try in 8x56R.
Some time ago, I had seen handloading recipes that called for 4198 in 8x56R. The data shown was typical for other centerfire milsurp cartridges, i.e., recommendations in a range of 20.0 to 22.0 grains (using cast bullets of 175-200 gr. in weight) yielding a muzzle velocity in the range of 1700-1800 feet per second. I don't see how they got these results after conducting my own experiments as follows.
Using a 200 grain lead bullet and a starting load of 22.0 grains, a muzzle velocity of 1268 fps resulted with much smoking of the case from gas leakage. 23.0 grains wasn't much better, with a velocity of around 1300 fps. and the same kind of gas blow-by. Obviously, it was back to the drawing board for this one.
I pored over all the cast bullet rifle data I could find that used 4198 powder. It was just like I said, with recommendations for all the large non-magnum centerfire rifle cartridges calling for loads of 4198 in a range from the low 20's to the upper 20's in grains. Then I started looking at .348 Winchester. The .348 Win. case is not unlike the 8x56R, rather shaped like a bell. The bore size or the 8x56R is closer in size to .348 Win. than the .308's. Case capacity is similar. Low and behold, the recommended load range for 4198 with a 187 grain bullet was between 25.0 and 35.0 grains, yielding a velocity of 1700-1800 fps. This is the target velocity range for the other centerfire rifle cartridges using loads of 4198 in the mid-twenties, and what we might (vainly) expect for 8x56R. There is something about this shape of case that affects how 4198 performs in it.
After making this discovery, I took some preliminary loads containing 32.0 grains of 4198 (same 200 grain lead bullet) to the range. These limited experiments came up with a very clean case, visually normal primer condition, and a muzzle velocity of 1791 fps. Accuracy seemed to be reasonable but more testing is required and forthcoming. I have a new set of test cartridges loaded and ready for when the range is no longer flooded. So, the happy results so far indicate that 4198 is a good powder for the 8x56R; it's just that we must use a bit more of it.
Results of today's shooting, Feb. 7, 2009:
Two test rifles were used, one having a bore size of .330, the other sized at .333. Two different loads were prepared indentically except for bullet diameter.
.330 bullet, 200 grain RNL from Lee mold.
Graf brass
30.0 grains H-4198
WW LR primer
Average muzzle velocity: 1733 fps
Standard deviation: 17.94 fps
.333 bullet, 200 grain RNL from Lee mold
Graf brass
30.0 grains H-4198
WW LR primer
Avg. muzzle velocity: 1725 fps
Standard deviation: 14.38 fps
Due to sight regulation problems on the .330 rifle, I wasn't able to assess accuracy on that load. As to the .333 bore rifle, I was able to create a diagonal string 1.5 inches long at 50 yards which was acceptable accuracy for me. Due to the bullet drop of the 200 grain bullet with this reduced charge, I had the rear sight ladder flipped up, and the crossbar set on the lowest setting.
Since there is some issue of positional sensitivity between the powder and the primer with these reduced loads, all shots were fired with the primer down.
I like 4198 and have used it for years in reduced charge loads for milsurp centerfire cartridges, full charge loads for .222 Rem. and .223 Rem., and for medium charge loads in .45-70. I also used it in my .375 Win. when I was loading for that caliber. All around, it's been a very helpful propellant for me. For this reason, I decided I would give it a try in 8x56R.
Some time ago, I had seen handloading recipes that called for 4198 in 8x56R. The data shown was typical for other centerfire milsurp cartridges, i.e., recommendations in a range of 20.0 to 22.0 grains (using cast bullets of 175-200 gr. in weight) yielding a muzzle velocity in the range of 1700-1800 feet per second. I don't see how they got these results after conducting my own experiments as follows.
Using a 200 grain lead bullet and a starting load of 22.0 grains, a muzzle velocity of 1268 fps resulted with much smoking of the case from gas leakage. 23.0 grains wasn't much better, with a velocity of around 1300 fps. and the same kind of gas blow-by. Obviously, it was back to the drawing board for this one.
I pored over all the cast bullet rifle data I could find that used 4198 powder. It was just like I said, with recommendations for all the large non-magnum centerfire rifle cartridges calling for loads of 4198 in a range from the low 20's to the upper 20's in grains. Then I started looking at .348 Winchester. The .348 Win. case is not unlike the 8x56R, rather shaped like a bell. The bore size or the 8x56R is closer in size to .348 Win. than the .308's. Case capacity is similar. Low and behold, the recommended load range for 4198 with a 187 grain bullet was between 25.0 and 35.0 grains, yielding a velocity of 1700-1800 fps. This is the target velocity range for the other centerfire rifle cartridges using loads of 4198 in the mid-twenties, and what we might (vainly) expect for 8x56R. There is something about this shape of case that affects how 4198 performs in it.
After making this discovery, I took some preliminary loads containing 32.0 grains of 4198 (same 200 grain lead bullet) to the range. These limited experiments came up with a very clean case, visually normal primer condition, and a muzzle velocity of 1791 fps. Accuracy seemed to be reasonable but more testing is required and forthcoming. I have a new set of test cartridges loaded and ready for when the range is no longer flooded. So, the happy results so far indicate that 4198 is a good powder for the 8x56R; it's just that we must use a bit more of it.
Results of today's shooting, Feb. 7, 2009:
Two test rifles were used, one having a bore size of .330, the other sized at .333. Two different loads were prepared indentically except for bullet diameter.
.330 bullet, 200 grain RNL from Lee mold.
Graf brass
30.0 grains H-4198
WW LR primer
Average muzzle velocity: 1733 fps
Standard deviation: 17.94 fps
.333 bullet, 200 grain RNL from Lee mold
Graf brass
30.0 grains H-4198
WW LR primer
Avg. muzzle velocity: 1725 fps
Standard deviation: 14.38 fps
Due to sight regulation problems on the .330 rifle, I wasn't able to assess accuracy on that load. As to the .333 bore rifle, I was able to create a diagonal string 1.5 inches long at 50 yards which was acceptable accuracy for me. Due to the bullet drop of the 200 grain bullet with this reduced charge, I had the rear sight ladder flipped up, and the crossbar set on the lowest setting.
Since there is some issue of positional sensitivity between the powder and the primer with these reduced loads, all shots were fired with the primer down.
