Seating depth, runout, change in brass? Or primers? New lot of powder? If nothing has changed then maybe you weren't in the middle of a node but on the edge of one. Weather changes can affect that. Just some ideas.
I have a 260 remington with a criterion light varmint barrel/ 1-8 twist.This barrel replaced a factory barrel. Gun has a accustock and accutriger. Had this thing shooting extremely well. Groups all of a sudden really opened up. Did nothing to the gun. Probally had about 350 rounds thru it when this happened. Cleaned it more than once and can't seem to find a load that it will shoot nearly as good as before. Was shooting 0.350 groups at 100 yards with accubond 130 and 140 grain bullets. Having a hard time finding the inch mark right now. Ideas???
Seating depth, runout, change in brass? Or primers? New lot of powder? If nothing has changed then maybe you weren't in the middle of a node but on the edge of one. Weather changes can affect that. Just some ideas.
A little more info would be a good thing but im gonna go with the things to start with....check action, base and scope ring screws if all good id do a tracking check on the scope if that turns out ok pull the barrel and action out of the stock and check the contact points of the action and lug for damage.
Have you tried a good copper solvent? Try using gun slik foaming bore cleaner and get all the copper out.
Are you reloading? If so, do you have a temp insensitive powder? Hot weather to cold weather could be a huge deal in accuracy of a load.
Have done all the above. Was using IMR 4064 powder. Used gun slick. Also Butchs Bore Shine. Brass was new and all the same Lapua. Always trim and debur in big lots, have 200 rounds. Powder is out of a 8 lber. Primers all out of the same 1000 lot box. Rings are tight. Scope is a Nikon pro staff 4x12. Have not checked the base. Put that on and use blue lock tight like on all my other rifles. Have a bunch of different bullets/powder combos loaded up last night, now need the wind to slow down.
Someone please find a solution, I have the same problem!
Find a Smith with a bore scope, but it is full of carbon
There is something you have missed here, what it is I have really no idea. One thing I know is, after doing a really good cleaning, the barrel needs to once again be fouled. Also, if a carbon ring has formed somewhere in the barrel, it needs special attention. Another thing may be damage to the crown?
If any of the above recommendations don't solve the problem, free to shoot us an email at contact@criterionbarrels.com. We'd be more than happy to help troubleshoot the problem and get that rifle back to performing like it was.
IF and I say If there is a carbon ring, what's the correct way to get rid of it. And I do know it takes a few shots to refoul a clean barrel
Jim (Apache Gun WOrks) recommended I use Wipe Out foaming bore cleaner. It did the trick for me. I used it maybe 4-5 x over the course of several days. Not sure if that was necessary, but it worked great.
Other than trimming length, what else have you done to maintain the brass? Are you checking the headspace to set FL sizing, neck sizing, annealing, etc?
I'd say that the root of the problem is probably the scope. Sounds like it's dying. Try a known-to-be-good, preferably higher quality scope, to rule out this possibility. Not trying to put down your equipment at all, but it happens, even with higher quality scopes.
from what youve said its your scope as you have ruled out all other problems for the most part and i REALLY doubt its carbon with only 350 rounds through the barrel...like i said do a tracking check on the scope...set up 2 targets at 100(200 would be better) and shoot for center on a 3'tall by 2' wide piece of paper with 1 black dot dead center when your on or close switch to the clean target and dial up 5moa and aim at the dot then down 5moa aiming at the dot then back to zero then repeat the above but going left then right with scope on 0...i bet you find your scope not tracking true.
My first thought is it's your stock, bedding or torque. I have to admit I know nothing about the accu stocks. My second quess would be the scope. Have you changed the way you seat bullets possibly introducing runout? Is your scales repeatable?
I guess this is part of the fun of shooting and reloading is learning how to chase down the problems when accuracy goes south. Hope you figure it out and share the fix with us. Good luck.
When you shot your good groups what was the temp outside? What was the temp outside when you shoot the terrible groups? IMR 4064 is somewhat temperature sensitive, if the temp changed a bit, you may have shifted out of the Optimal Charge weight for that combo.
I am not an expert loader by any means. Self taught. I talked to several guys who belong to a local club about this barrel. One asked about annealing. I have not annealed the cases. But with only about 4 rounds thru each case two of the guys agreed I should not have to do that yet. I put this barrel on myself and checked headspace with a go, no go, and a field gauge by foster. I am FL sizing and the die is set correct. I am not new to reloading, been doing it for 30 years, but still have lots to learn and want to know. If there is a carbon ring can you feel it when you run a patch thru?? Temps when I first shot were in the 60's-70. Now in the 30's. I did shoot today and may have found another load. Very frustrating. I shoot 4064 in 5 other rifles and never a issue until this year. Now my 338 win mag won't shoot it. Switched that over to H4350.
Look to your scope as others said. 4064 is like most other powders and can exhibit sensitivity to temp change. Federal still uses a similar powder in the FGMM stuff for .308. Velocity difference can be as much as 1 fps per 1 degree. So that could be a 30-40fps shift. If your on the edge of a node that could easily push you out. You mentioned you had h4350. That is by far the most popular powder for the .260 with bullets over 120 gr. maybe a powder switch is in your future. Hope you find the issue.
Ok im going to be the bad guy here and tell you.....it is either your scope or you!!!....a 30 to 40fps spread WILL NOT cause the problems your having....a carbon ring(which ive never heard of)is NOT going to cause the problem.....CHECK YOUR SCOPE LIKE I TOLD YOU!!!!!! If you scope is tracking true then the problem is you!!
Am going to check the scope out. I don't think its me. I have the same scope on a 338. So while the barrel is cooling off on the 260 I am shooting the 338. shooting way better groups with the 338 than the 260. Off to the deer stand this morning. Then hopefully have this issue resolved before my trip out west. Thanks for all the advice will post on what happens to the 260.
I'll second what longrange said.
When you are certain and for sure there is nothing wrong with the the rifle always check the scope. Swap it with a spare if you have one or run a box test.
After the scope is confirmed as good the last possibility is the shooter and his technique. How stable and consistent is the position? Breathing and trigger control? Follow through? Flinching? Eye relief? Grip?
Try a different scope. That one is entry level and may have gone 'west'.
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