Thanks all you guys for the suggestions and comments. I'm going back to the range Wednesday with the new Set up and a fresh ladder of 123 SST's to see if I have the problem put to bed. So far, my best was .68MOA before the front mount worked loose but I'm exploring the 41.0 to 42.5 grain range (H4350) to see if there is more to be gained. I hope there is!