Big magnums developing pressure signs as barrel warms?

[RDM416]

Two thoughts....... One, I agree with the previous post about letting the barrel cool a little between shots. I shoot a 338/378 improved and have seen the same thing to a lesser degree. It really heats the barrel up fast.

Two, I ran into some pretty severe pressure problems by having the bullets seated all the way into the lands, backing off the lands allowed me really increase velocities before I run into pressure issues.

Three, (thought of another thing) This is a long shot, but do you turn necks? I was using unturned necks and the neck portion of the chamber was too tight and not allowing the bullet to release creating a pressure spike. This seemed to get worse as the barrel heated up. I assume from the heat related expansion of the barrel causing the neck to be even tighter as the barrel heated up. Started turning necks and the problem went away.

 

[Marine sniper]

Two thoughts....... One, I agree with the previous post about letting the barrel cool a little between shots. I shoot a 338/378 improved and have seen the same thing to a lesser degree. It really heats the barrel up fast.

Two, I ran into some pretty severe pressure problems by having the bullets seated all the way into the lands, backing off the lands allowed me really increase velocities before I run into pressure issues.

Three, (thought of another thing) This is a long shot, but do you turn necks? I was using unturned necks and the neck portion of the chamber was too tight and not allowing the bullet to release creating a pressure spike. This seemed to get worse as the barrel heated up. I assume from the heat related expansion of the barrel causing the neck to be even tighter as the barrel heated up. Started turning necks and the problem went away.

I do turn necks, the chamber neck is .333, loaded rounds go .305-.331. The bullets are seated to touch the lands, I am going to back them off a bit and see if that helps. I will let the barrel cool much longer also.