I have an HK 91 IC date code and recently came across an ARMS G3 claw mount.  I mounted it and locked it in to place.  Hooks up solidly but appears to be slightly canted to the right looking down the sights.  

From what I can tell their seems to be no way of adjusting this but I am new to these style of bases.  Maybe someone here can point me in the right direction.  Could it be the base or the receiver? Base looks new, receiver claw notches look a little scratched but not damaged or deformed in any way.

ETA:

Well, called A.R.M.S. (What I should've done first) and was told they stopped making the claw mount about 15 years ago.  Apparently they licensed it off to a company
called Mounting Solutions Plus http://www.mountsplus.com/

Gave them a call and they were very helpful.  Will be sending in the mount to get it looked at.

Its likely the belville washers in the mount. Its probably too tight, there are two pads on the mount that lock it to the top of the reciever, if you have too many washers it won't lock and likely will be sorta canted. IIRC many years ago I had a similar issue and had to remove a few (which worked out since my HK claw mount was too loose and I put them there and it fixed both).

Oh where was that site 15 years ago when I needed it...