New barrel is a Bow4 contour(essentially a 1.200" shank 3b) Hawkhill 7.5tw finished at 22" and cut with the Alpha 120fb reamer, tl3 tenon.
Load info:
Formed alpha ocd 22gt brass, 33.5 N150(cool burn) 80 eldm, cci450
Inital Velocity: 3140, after 65 rounds: 3185
No psi signs.
ES of 5 shot groups on avg: 20-30, not great, will likely move to H4350 or RL15.5 after break in, with 85.5 Bergers.
I planned to shoot lighter bullets with the short barrel for velocity purposes, hence short freebore. I may throat it, as the 77tmk has a very long bearing surface. 85.5 Bergers, 80/75 Eldm sit very well in the neck with the short freebore. The 77tmk, 88 eldm and 90 atip all have maybe 20-30k of seating depth adjustment before the bearing surface is going below the neck shoulder junction.
Start up load, 33.5gr N150 with 80gr eldm, I have approx 65 rounds on the barrel and has speed up about 40fps thus far, with no cleaning, other than scrubbing out the chamber and barrel after receiving it from the smith.
Velocity is currently around 3180 and it's shooting very well. I loaded up 100 rounds, first 15 rounds were just firing all the dummies that I made to find lands if possible bullet candidates. I started with a seating depth test on the 80 eldm -10k to -73k jump in 007 steps. The barrel is shooting very well this far, 5 shot groups averaging half moa, some in 3s and 4s, others in 6s and 7s. The -10 group(not in picture) and -38/-45 groups look very good. I'll likely seat the remaining 50 rounds to -40 to finish inital break in following a barrel scrub. Attached target is 1/4" grid.
