Thread: Special cases in a magnum and accuracy

Originally Posted by Ackley

P38 what weight of trail boss did you use and what projectile weight. I have some 300gn hornady's that I was going to load up sub but would like a starting powder charge. I'm don't want a stuck projectile

@Ackley

I used 240 gr and 300gr hornady JHP and 240gr cast FP all worked great, the 300gr worked too great though.

I smashed a couple of goats with this load, instant kills but fair made a mess of them both. Almost made me feel sorry for them.

Trail boss is pretty forgiving in the amount you use but the goal to achieving consistant subsonic ammo is to keep the muzzle velocity below 1050fps.

with the 240gr projectiles I was using 7grs of trail boss, and about 6 grs with the 300gr projectile.

Here's the formula to use to find your starting load and maximum load for any cartridge/projectile combination.

This formula may be used in both rifle and pistol applications:
1) Find where the base of the bullet to be loaded is located in the case and make a mark on the outside of the case at this location. Then fill the case to that mark with Trail Boss, pour into the scale pan and weigh. This is your maximum load. Pressures will be below the maximum allowed for this cartridge and perfectly safe to use!
2) Take 70% of this powder charge weight (multiply the maximum load from step 1 by .7), and that is your starting load.
3) Start with this beginning load and work up to your maximum charge, all the while searching for the most accurate reduced load.

Do not compress this powder and keep the MV at 1050 fps for subsonic performance.

Cheers
Pete