Troubleshooting load development for new barrel

[superduty211]

Good evening,

I had a custom heavy varmint barrel installed, bedded, action trued, new recoil lug etc, and have been having problems finding an accuracy node.

My factory barrel (light varmint) on my .308 Remington 700 was very accurate for a long time but when it dropped off I had a custom barrel put on.

I was using it for long range matches and will be shooting FTR to 1k once I fix this problem.

Factory was 1-12". Custom is 1-10" still in .308.

My load was varget and 178 amax. So for a couple of months I've been doing break in and trying to find OCW.

So my thoughts have been "barrel isnt broken in yet" to " its my lousy shooting causing this". So after all this effort I have my suspicions in this area:

The barrel will not group reliably with that amax bullet. ( I still have 7 boxes) 1.5 MOA-ish or sometimes worse @ 100 yards. The groups are erratic. The correct answer is of course, try a different bullet. Barrel was broken in according to manufacturers instructions and I have broken the 200+ round mark. I have tried charge weights accross the whole spectrum for this round and powder. I even played with the OAL just to see if somehow that might clear things up. It didnt.

I have moved from a 12" to 10" twist. And I hear different things, such as: "1-10 is a good all around barrel for bullet weights", to: "they only like the heavier stuff".

So my question is what would you try first?

-Move to a heavier bullet, like 195 TMK or one of the heavier ELD's?
-Try 168 TMK, with the higher BC than the previous 168's, would seem to make this viable for long range?
-Stay with a bullet about the same weight and try a different brand, like sierra?

I will try all of these eventually to find what it likes, but I thought maybe you could help me speed up the process. I am wondering where I should start first, handloading-wise. I have checked the rifle over with a fine tooth comb and found no problems. Bedding and everything in the stock looks great. No mechanical problems. High dollar scope. Stable set up on bench when shooting. Lapua brass. Benchrest primers. Suspicious it is the bullet itself. Factory barrel was fine with alot of jump on the amax. Im restricted to internal magazine for OAL. Not interested in loading single rounds.

Thanks in advance.

 

[Lunchbox27]

Having been there myself, I can understand your frustration. If you were able to get solid groups before with the old barrel and handloads I would doubt the shooter is the problem here. If you trust the barrel maker and the smith that did the work I would start with some Federal Gold Match 175's. I have never shot a box that didn't shoot well in a 1:12/1:10 twist. At 200 rounds that barrel should be broken in and you should be seeing some good groups by now. Your components seem solid and most using Varget/Lapua/178's find a low node around 42 grains and a high around 43.5-44 grains.

Start out with a box of FGMM 175 and Hornady's 178 ELD-M ammo and see what you get. Eliminate the reloading process as your just burning through $$ and time trying to figure out what is going on. If the match ammo still produces over 1 moa at 100 yards on the first few groups, play with your actions screw torque settings. If it's pillar bedded the actions screws should be at 65" pounds but it might like something lighter. Take a torque wrench with you in inch pounds and adjust. Shoot your first group at 65" pounds, then lower it to 60" pounds for the front and rear.

If after all that it's still not performing, contact the smith and let him know your troubles. A good smith will stand behind his work.

 

[superduty211]

Actually I ran across a box of 175 GMM I didn't know I had. I'm going to try it like you said. My action is set to 65 lbs with a torque wrench but I'll try backing it off a tad if the GMM doesn't group well. Thank you so much.