Been out shooting the 8mm again. Loaded up some 2.8 gr trailboss loads and am seeing a fairly consistent 650-660 fps. My barrel slugs to slightly under 0.324" which would explain my low speeds with 2.8 gr trailboss.
Previously I tried softer loads, but noticed that under 2.6 gr the cases wouldn't expand enough and some burned powder would sneak backwards beside the case.
2.6 gr Trailboss - 610 fps
2.7 gr Trailboss - 630 fps
I'm using JetHunter's excellent cast bullets. They are very consistent at 0.327", 112.5 grains and 13.716mm length.
How I've been loading them
1. Trim starline 32-20 casings to 27.5mm.
2. Run the casings through a Hornady 8mm lebel rev sizing die.
3. Run the casing through a Hornady 8mm lebel rev expanding die just enough to allow the 0.327 bullets into the case mouth.
4. Prime the casings with CCI small rifle primers.
5. Measure and load 2.8gr trailboss powder.
6. Seat and lightly crimp bullet with a Hornady 8mm lebel rev seating die to an overall length of 34.8mm.
After the first shot the cases fireform to the cylinder and require a little trim. After that they retain their dimensions. I have loaded some cases over 5 times and haven't seen any splits or anything unusual, though the primer pockets are definitely getting looser. They fit nicely in a 38/357 case.
Technically the OAL should be 36.7mm, however I've been seating to 34.8mm to avoid crimping in the lube groove of the bullet.
Definitely a great prescribed antique to use as a shooter.
