I purchased an eotech 512 and a 9 bc cam mount from S.W.F.A. in Feburary.  I mounted it onto a Colt A2 carry handle.  I really didnt like the way the unit mounted to the carry handle.  I installed it like the instructions said, but when I would turn the mounting nut (at bottom side of carry handle) it would get somewhat tight, and then loosen, and it did not really fit flush to the bottom side of the carry handle.  So, I just tightened it as much as I could and today, while shooting, it came loose at the carry handle.  Am I doing something wrong?  I just cannot for the life of me figure out how to make that nut stay tight on the carry handle.  It almost seems to me that it needs some type of rubber bushing between the carry handle and nut, because the carry handle is tapered.  I hope this makes sense to everybody.  Thanks for the help.

I just did the same setup with the 552 rev e on my Olympic a2 carbine,I have'nt shot it yet.but the mounting nut seemed to go on alright,it appears to be an acorn type nut where it shouldn't loosen when firing.My problem seems like the eotech site doesn't line up with the iron sites it still seems to high.  

I think my gooseneck would mount fine if it wasn't for the ridge on the underside of the carry handle where the nut goes.  Oh well, I wrote S.W.F.A., and asked them for advice, I will just wait and see.  

I know what you mean about the eotech not lining up with the iron sites (too high).  Since they use AA batteries instead of the shorter lithium batteries, the battery casing for the eotech is too long to mount as low as the forward hand grip.  Mine is as low as it can go without touching the front sight post......I guess its better than nothing.