Yesterday's Weapons Forums

My trip to the rifle range today was a very pleasant experience, slightly overcast weather of 60 degrees. I like to keep working on different data for the 8x56R Austrian cartridge for a couple of reasons. For one, there isn't an over-abundange of data for this orphan cartridge to begin with. For another, I like to see if I can make it a more versatile cartridge for my own purposes.

My first loads were:

175 grain Buffalo Arms spitzer bullet
40.0 gr. IMR 4320
WW LR primer
Graf case
Average muzzle velocity 1972 fps
Standard deviation 24.01
Accurate, prints 5 inches high on target at 50 yards

175 grain Buffalo Arms spitzer bullet
42.0 gr. IMR 4320
WW LR primer
Graf case
Avg. muz. vel. 2114
Std. dev. 11.66
Accurate, prints 4 in. high on target at 50 yards

These are the first loads I have tried in 8x56R using IMR 4320. This powder has been one of my favorites for years. It's not super slow, but it's on the slow-ish side. I've used it with success in .223 bolt actions and .30-06 for years. I have had enough success using IMR 4895 in this caliber that it seemed like IMR 4320 might be a good one too, since they are next to each other in the IMR burning rate chart. I wasn't disappointed; I like IMR 4320 for this caliber.

Not long ago, I posted some sub-sonic velocity reduced charge data for this caliber using Trail Boss powder and a 200 grain LEAD bullet. These results were most satisfactory. Based on these results, I decided to use Trail Boss on some sub-sonic loads using lighter weight .330 diameter bullets. To this end, the following load information is offered:

115 grain Graf plated .330 pistol bullet
6.0 gr. Trail Boss
WW LR primer
Graf case
Avg. muz. vel. 1088 fps.
Std. dev. 27.50 fps
Reasonably accuracy at 50 yards; printed 6 inches high on target.

155 grain Graf plated .330 pistol bullet
7.0 gr. Trail Boss
WW LR primer
Graf case
Avg. muz. vel. 877 fps.
Std. dev. 21.32 fps.
Poor accuracy; prints 8 inches high on target at 50 yards. Doesn't seal properly and smokes cases badly. I don't like smoke in my face.

On the above loads, note the drop in muzzle velocity on the charge that is one grain higher. In my limited experiments using Trail Boss powder in reduced rifle charge cast bullet loads, once a certain load threshold is crossed, everything goes haywire.

One other reduced charge load using a light bullet was tried, and is:

115 grain. RNL pistol bullet (Liberty Bullets)
7.0 grains Trail Boss
WW LR primer
Graf case
Avg. muz. vel. 1070 fps.
Std. dev. 47.16 fps.
Accuracy so-so, printed 4 inches high on target at 50 yards. Note that the muzzle velocity when using this lead bullet is about the same as that obtained using 6.0 grains of Trail Boss with a plated bullet. The point here being that the copper plating doesn't seem to slow the bullet down as against the lead. So, one grain less of powder with the plated bullet and it's going the same approx. speed as the lead bullet. The plated "jacket" is a softer material than the gilding material used on "real" jacketed bullets. Just the same, there is no factory load data for Trail Boss using any jacketed bullets that I am aware of.