Local gun shop has two buggered Tikka actions with lug setback from being run "too hot". They are not "bullet proof" particularly with magnum cartridges that produce higher bolt thrust. Lug setback = inconsistent headspace = inconsistent ignition.
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Local gun shop has two buggered Tikka actions with lug setback from being run "too hot". They are not "bullet proof" particularly with magnum cartridges that produce higher bolt thrust. Lug setback = inconsistent headspace = inconsistent ignition.
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 .
Is there anyway to check that or only a gunsmith can tell?Quote:
Originally Posted by Tentman
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 assumQuote:
Originally Posted by norsk
Get the vernier calipers out and measure everything.Quote:
Originally Posted by tibo
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.
This comment touches on something that doesn't seem to be given enough consideration in cases like this. When metals are heavily worked, as in barrel manufacturing, there is substantial stress introduced, so much so that I often wonder at a barrels ability to resist bending like a banana when exposed to work as in a projectile screening down the bore. To me it is not at all surprising when a comparatively thin sectioned steel tube reacts by bending after a few rounds only to return to its happier state once allowed to cool. The fact that it once didn't seemingly react in the same manner is also not at all surprising.Quote:
Originally Posted by distant stalker
No offense taken I have eliminated myself from the equation :thumbsup:Quote:
Originally Posted by Ground Control
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?Quote:
Originally Posted by Tentman
I would have thought so but it's easily checked and eliminated, a borescope will see it.Quote:
Originally Posted by tibo
This would create a headspace issue as mentioned, I think you would notice it being a precision reloader.Quote:
Originally Posted by tibo
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:thumbsup:
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?
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. . . .
All right I'll say it if no one else will. 700 rounds of over max loads in a hot 7mm. 1.5mmof throat erosion and likely a rough throat as well. The barrel is likely poked and the lugs may be set back from the over max loads,
Next question. GPM.
700 rounds to determine acuracy = $? I can't even count that high, as above the barrel is probably shot out.
Sorry to hear you bought a dud, probably time to call it dead and move on.
Hi ,
I had same problem….
Mine is now fixed .
I changed the the pill to 175 Eldx added exactly 43 th of jump ( took a while to find to the right jump ) same brass ADG , same initial load but load came down to 2850 from 2950 pm me if you want any more details
Cheers
Les
Clickers?
Is your die sizing almost all the way down every time?
Na no clickersQuote:
Originally Posted by riflegus
Well well well… Found the issue… one of the last thing I had to try, use virgin brass. I think this hot load I was firing hammered the brass and they were toasted after 6 firing. The primer pocket were rather on the loose side even if still holding primer.
Just shot a 0.5moa 5 shot group and 4x 3shot gpe all between 0.3 and 0.5moa.
Thanks everyone for all the suggestion. Will still need to get a new barrel in few months I’m struggling to live rifle alone in the safe
Glad you found the issue
Recently watched one of the Backfire youtube videos on 7mm prc and one issue alot of people are having is a carbon ring build up in the lands. Apparently frequently cleaning resolved the issue. New brass may be shorter and not running into the lands as far resulting in not touching the carbon ring
https://youtu.be/Mr9i3igADEI?feature=shared
My Saum had this issue but it wasn't the brass it was the projectile when it hit the carbon ring the pressure would go sky high.Quote:
Originally Posted by Steven1
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Thanks, in my case it was not a carbon ring issueQuote:
Originally Posted by Steven1
Get a Bartlein. My 7 prc is probably around 600 rounds or so now, shoots great. Re barreled from a rem mag that did exactly what your prc is doing, pitted barrel. Haven't heard great things about hardy..