Accuracy gone south, need advice

[crittergitter]

Well, my 338 - 300 RUM has been a tack driver until recently. I had a string of misses the other day at 570 - 670 yards that baffled me. I checked the gun on a 600 yard target and centered it right after the incident. I checked the action screws and scope rings and they were all tight. After making sure everythig was tight, I re-sighted in at 250 yards. It shot 4, .75" groups at that range. I did have trouble adjusting windage back to zero. It failed to move enough after the first group, and moved too much after the second group. Scope is Elite 4200 tactical (6x - 24x). After 16 rounds with no problems, I packed up. Today, I went back out and missed a deer at 280 yards. A test on a spot on a tree at 275 yards resulted in the first hit being 7" low and 4" right. The second shot either missed the tree completely or went in the same hole. I can't find anything loose but there are scuff marks in the first inch of my bedding compound (I bedded about 5" in front of the recoil lug).

Any suggestions about possible problems? Can I get away with fully free floating the barrel? The barreled action, rail, and scope weigh about 12 pounds. The barrel is 34".

Thanks for the help.

 

[BountyHunter]

Swap scopes first to ensure it is a gun problem and not a scope gone bad.
Sounds like scope problem.

BH

 

[rem300ultra]

I agree with BountyHunter. Check your scope first.

 

[Coyboy]

Check the bullet clearance holes thru the brake, the gas cutting can cause the leading lip on the clearance hole to get pushed around and roll a bur into the hole thus causing problems. Un hardened brakes are more suseptable to this.

 

[crittergitter]

Thanks guys. I assume that the scope isn't holding zero. Thanks for the muzzle brake suggestion. That's not a condition that I would have thought to check.