Hello,

Does anyone or does anyone know of anyone who can do repairs on FP PEQ-15 units. Mine currently zeros but will not maintain zero.

Have you tried to zero out the adjusters? Turn the  vertical counter clockwise until it stops, the count the clicks full clockwise, then turn counter clockwise 1/2 the number of clicks. Rinse and repeat for the left/right adjusters. After try to see if it will hold zero with live fire.

I have not tried that but I will.

Ruled out hand guard and Mount being loose?

Yes not a loose Mount or rail.

Definitely this, check it by grabbing the LAM and twist/rock in different directions. I once diagnosed a scope that would constantly walk the zero every other shot. Grabbed the scope torqued it different directions and found the upper pic rails where out of slightly out of  spec after mic'ng the top rail.

OP also you can simply overlap the vis laser to your RDS at say 10 yards, with the stock collapsed, smack/bump the butt of your rifle on the ground several times to simulate live fire several times and see if your zero walks.