03-16-2022, 10:56 PM
I used an AT3 Tactical billet upper/mlok rail combo set for my 6.5 Grendel rifle. My Criterion barrel was a very tight fit (no heat required, but some elbow grease - even with LocTite on the extension). The hand guard is keyed into the upper. The barrel nut does not have to be timed to attach the hand guard - they have a very effective attachment system.
https://www.at3tactical.com/products/at3...uard-combo
https://www.at3tactical.com/products/at3...uard-combo

