Need help dialing in a load...

[lar45]

Okay, so I changed several things, so I'm not sure what was wrong, but I am happy with today's limited shooting.
I put a Vortex scope on, took the center out of the Tromix Linear Comp, and switched to CFE-BLK.
I can use the same loads tomorrow with the Linear Comp put back in to see if that has any effect on the groups.
The velocity was lower with CFE-BLK. I think there's still room to go higher. The bolt wasn't locking back all the time.
I ran out of prepped brass, so I didn't load anything higher than 36.5gns.

[TurnipEaterDown]

Lar45 - how did the repeat go?

BTW: 200 @ 2300-2400 Seems peppy for what is in practical terms a 35 Rem AR, though do realize you likely are targeting higher operating pressures. 2-300 fps seems quite a gain over the 35 Rem.
Have you run an analytical model to guesstimate the pressures? Have you done a water capacity comparison w/ 35 Remington?

BTW - I know 680/1680 is a good powder in the 357 Herret, but when I gave it a go in 35 Rem some weird things started rearing their head for me. Perhaps try something marginally slower like 4198?

[Gav-n-Tn]

I read or watched somewhere about dialing in a load using increments of 3% of your first good group as you progress up or down the ladder. I hope my post makes sense.

[lar45]

Hello, I reshot the same loads with the center piece of the Tromix comp and got essentially the same groups.
A friend suggested maybe shimming the comp out to try and tune the barrel. Kind of like the BOSS systems on the Browning rifles...
I shimmed out progressively to .0060" in 20thou steps and at 60 got some really nice tight groups.

I noticed that my round is very close in case capacity to the 360 Buckhammer, it has around 1.5gn more capacity at 47.5gn of H2O. So I've been comparing Hodgdon's data with Quickload to come up with a reasonable max load.

This barrel seems to be real touchy as to what it's fed, but I think it's shooting great for a home built AR in a hot 358 short cartridge.
I was going to take it Hog hunting this weekend, but my buddy's dog got hurt and needs bandages changed twice a day for 2 weeks...
So I'll go in 2 weeks...
Maybe in the mean time, I'll see if I can get the Speer 180s to shoot.
I took a stab at the Lee 200 and they were all over the place at 25yds
I think I'll slow them down and load with 2400?

Thanks everybody for the help

[charlie b]

I suspect most of the issue is the comp. As you noticed it can change things dramatically.

I'd start over with a good ladder test. You will waste less ammo and find the node for your barrel. If needed you could then look at changing seat depth and comp shims. Change one thing at a time.

The cast bullets running that fast need some special attention. Be picky about any flaws and weight sort the bullets. Make sure they fit your bore. You also might want to seat them so they lightly engage the rifling. If you load them down too far you will run into powder position issues. Tipping the barrel up between shots will help that.