Heavy bolt lift related to bore diameter?

[Jody Simcox]

Could you barrel or chamber not be square or concentric with the bolt/action?

I’m not able to rule out anything, to be perfectly honest

 

[Jody Simcox]

I will say that when I checked Hodgdon Load Data online, their parameters for a 107 gr bullet were 30.6-34 gr for Varget...when I talked to them on the phone, they gave me (for a 109) 29.?-32.8 gr... that would put the 32.5 I was using pretty close to max. However, GG made a video shooting a 110 A-tip with 34 gr...no heavy bolt lift, no ejector mark. GG said “If you’re having problems, it’s not the load”

 

[BoydAllen]

I know that most will not believe me but if the chamber dimensions are too close to those of the unfired brass, bolt lift problems will be the result. After the first firing, if the die is small enough, the situation will improve. I have seen this happen. A friend had a Remington 6BR chamber that was polished out just enough to take Lapua brass. Medium loads showed bolt lift issues. Recutting the chamber with a Lapua dimensioned reamer solved the problem. After that, he could pour on the coal.

 

[Texas10]

Perhaps you've already done this, but I'd run my borescope camera down the muzzle until at the throat, chamber a piece of brass and make sure I didn't have a fit issue. Simple test that eliminates a common cause of high pressure.