Yes this is a Mk 2 variant from Numrich. I certainly didn't overtighten the lock rings and just followed the instructions in your book. The were left finger tight initially. I had a collimator fitted at the time and noted the settings for future reference. I tightened the rings just a bit to make sure everything was secure and checked the collimator to see if the reticle had shifted which it had and thats when I discovered the problem when I tried to adjust the elevation. there wasOriginally Posted by Peter Laidler