Ridgewalker

Welcome.

The BART II tools I got, one each for a Spec AR15 and a Aero M4E1, both had flats, and both worked well. The Aero M4E1 BART ll version also appears to fit the Seekins iRMT-3 uppers. Haven't tried it yet, probably will give it a whirl soon though. The instructions say to do it horizontally and not on a drill press, however I did do it vertically, but from below to keep the compound from running into the receiver. I also did it with a flexible shaft between the tool and the handheld cordless drill to help it run true and not induce a wobble or put uneven pressure on the face. I cleaned the receiver and tool with Hoppes then alcohol every time I pulled it out to check progress, which was often. Re greased and put more compound on the tool face every time too. I suppose the face trueing end will eventually wear out, but it will be on somebody else's watch in my case. When I do some some 308ARs later this year I will be buying those versions too.