Combo Barrel Extension Wrench and Lapping Tool

[jtallen83]

Interesting tool, coming from X-caliber doesn't give me the warm fuzzies though. If they made it well balanced then it should work fine but seeing that 1/4 inch drive on the end makes me wonder if there will be any wobble while lapping. PTG's lapping tools are $25 each and perfectly balanced. That and lapping tools are an expendable tool so eventually you are left with just a wrench.

http://www.x-caliber.net/bart-20

[COBrien]

I have a hard time wrapping my head around clamping the round "head" of the lapping tool in a vise.  No flats, no knurling, nothing. Just clamping your serrated vise jaws onto a "precision ground" tool.

Personally, I'd prefer a MagPul BEV Block and a PTG lapping tool. Granted, this won't work for "AR-10s" (am I the only one irrationally annoyed when companies generalize the term 'AR-10'? But I digress...). But a set of vise blocks for a .308 AR and a PTG lapping tool are still substantially cheaper than this... thing...

Edited January 10, 2019 by COBrien

[Ravenworks]

The lapping tool I got from Brownells was $50.

And the tool that went into the receiver and lugs had flats for the vise end and it was $45

[Ridgewalker]

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.