Thread: My 7mm PRC is driving me nuts…

Originally Posted by tibo

Been thinking about this, I would have experienced hard bolt lift wouldn’t I? Never been the case. Inconsistent ignition would also mean my SD would be up?

I would have thought so but it's easily checked and eliminated, a borescope will see it.

Looks like the only thing left is try a different projectile, there’s a box of 168 vlds on tm at the moment. If you can’t get something else shooting it looks like tentman might have identified the last option. Worth trying a different projectile though I reckon.

Maybe the " prc dream" is over. Meanwhile a little 7 mm rem mag waits🙂

I had the same issues with a 7mm saum some years ago same barrel but a carbon one.
I spent ages trying different powder and bullet combos in the end I listed it on here and told of all the issues I had and moved on to a factory Sako no more issues.

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Maybe your barrel shoots better at 2990fps and not at 2900. Try a lighter projectile at near 3k fps. Or push those same pills you were using back up to 2990fps with a different powder as you said you were using a fairly fast burn rate powder.
I have a 6cm that was shooting great at 3050fps but the load was too hot. Backed off to 2920fps and it shot poorly in comparison. I changed powder to get it back over 3k fps and also tried a different pill @3100fps and it was shooting great again. Clearly my barrel has better harmonics at over 3k fps. Your barrel could be similar .

I had a similar problem.

Something is moving. In my opinion your split groups are too consistent for it to be the barrel.

I would suggest measuring the external dimensions of your action and bottom metal to see if they are undersized and moving in the stock?

Originally Posted by norsk

I had a similar problem.

Something is moving. In my opinion your split groups are too consistent for it to be the barrel.

I would suggest measuring the external dimensions of your action and bottom metal to see if they are undersized and moving in the stock?

That’s what I thought too! I tried different stock and chassis and skim bedded a chassis. I don’t see any marks on the bedding job, the receiver moving would leave marks I assum

Originally Posted by tibo

That’s what I thought too! I tried different stock and chassis and skim bedded a chassis. I don’t see any marks on the bedding job, the receiver moving would leave marks I assum

Get the vernier calipers out and measure everything.

You might have skipped the reason ?

I had similar results with my 300 and both 225 and 208gn ELDMs. Changing powders didn’t help.

Switched projectile type and had instant velocity gain and grouping consistency.

I can’t explain why it shot well for you initially but it’s worth a try loading up something like a Sierra, Berger blah blah.

Get someone who is a good / known shooter to shoot some groups.
I don’t like to admit it , but I’m the biggest variable when it comes to accuracy with my Rifles.
I’m not trying to be a Smart Arse , but make sure that you have eliminated yourself from the equation.
I’ve had similar problems in the past and nearly pulled my hair out trying to solve the problem , mine was a damaged muzzle crown that wasn’t obvious, but was the cause of much drama.

Originally Posted by Ground Control

Get someone who is a good / known shooter to shoot some groups.
I don’t like to admit it , but I’m the biggest variable when it comes to accuracy with my Rifles.
I’m not trying to be a Smart Arse , but make sure that you have eliminated yourself from the equation.
I’ve had similar problems in the past and nearly pulled my hair out trying to solve the problem , mine was a damaged muzzle crown that wasn’t obvious, but was the cause of much drama.

No offense taken I have eliminated myself from the equation

Yes didn’t notice any headspace inconsistencies and didn’t see anything anormal on bore scope.

Few last things I will test:
-fresh adg brass.
-Retorque barrel just in case. Maybe pull it and refit, retorque
-could try other projectile, this batch of 180 eldm was shooting great though, inconsistency within batch could still happen I guess. Will measure and weight a few for the sake of it.

how about uneven bolt lug contact. Other than that just get a 6.5x55

Another thought. If you've kept targets from earlier testing try super-imposing them. Our brains play funny tricks and many a time I've shot several good 3-5 shot group, yay sub MOA. However if you look at several lots of groups with something like BallisticX it can be a bit disappointing. . . .

Another thing to check, do the action screws have plenty of clearance in the stock, if they are "tight" due to bedding compound getting down the holes then they are acting as recoil lugs and that ain't good.

What stock is it? Really snotty cartridges can cause the stock sidewalls to flex enough to cause accuracy issues ( Mauser sporters often had "side panels" on the stocks for this reason). If it's an alloy chassis maybe it has developed a crack?