chamber out of round?

[richard295]

Factory xp100 in 7mmbr . . . after firing, notice that the shell neck openings are not perfectly circular. Kind of like a flat spot on one side. Does that show that the chamber is out of round? This xp is about .8 moa and can't seem to improve after a lot of load development.

 

[Buzzbee]

Most likely the dent on the mouth is from hitting the receiver upon the ejection. Try ease the brass out using a finger applying pressure from above and see if this problem ensue.

Usually by installing a weaker plunger spring will fix this problem.

 

[USAPatriot]

Agreed. After I replaced my 700's firing pin with a fast locking model my case mouths started getting slightly flattened on one side during ejection. It's not a huge problem but does make it a little tougher during case prep. -Rod-