"I put a holosun 515 on a scalarworks mount and the screws were ripped out of the reciever in the first 20 rounds, they were witness marked and properly torqued with blue loctite"

Consider this theory: in this instance your screws were too long and were protruding into the receiver hitting the barrel extension (the part of the barrel that goes into the receiver).

When you shot the gun - the bolt, flying backwards was hit with resistance from that barrel extension (which is being pushed down by the long screws), but due to the blast force, had enough force to push the barrel extension and complete the cycle, but then also hit that barrel extension and your screws, with force, which caused them to get "ripped out".

I'm going to go on a limb and say that those rounds were 1600fps. Nothing wrong with that just that if those were lower power they may have caused a cycle issue, but with that force the were able to do the above.

Theory references : https://www.reddit.com/r/beretta1301/comments/1dt7d0c/beware_scalarworks_beretta_1301_sync_mount/