Sight in new gun

[jstagn]

Friend just received his new open gun with zero rounds and proceed to sighted in .   No problems.  After about 300 rounds gun lost zero by about 2 inches right and 1 inch high. Checked all screws especially red dot and mount. Also cmore lock was tight. Is this normal? Does gun need more break in? Thanks.

[dapribek]

No, this is not normal and I don’t feel this problem has anything to do with breaking in the gun. 

[Snoopy47]

I noticed my zero start to drift around 200 rounds with my C-More, but I had forgot to tighten the lock screws.

 

Since then, my zero as slightly drifted again (a few inches at 25 yards, but enough to stay in the A zone, but not dead center), not nearly as much, but survived an entire match, and lots of additional range time. 

 

I'd just re-zero, tighten everything down again, and see how long it can go from there. 

[zzt]

This happened often over time with the Slideride on my Open gun.  The one on my PCC stays zero'd, but I only shoot minor loads out of it.

[cperazza]

If all the screws are tight and you have confidence the sight is not moving, it might be time to talk to the manufacturer.

 

In my experience, it is rare but you might have a defective sight.  Good luck!