Tight squeeze for Bcm uppers
Tool worked as it was supposed to although on 2 Bcm uppers I used it on it was a very tight fit. I greased the shaft as recommend by Caleb but I still had to run the drill to get it to meet the face of the receiver and it rubbed some of the anodizing off of the interior of the receiver. Based on the question section this seems like a common issue for the Bcm uppers.
Would you recommend this?
Yes, I would recommend to a friend
Upper receiver lapping tool
Does as is expected very well made and very high quality as of anything produced by Brownells. Take some time and patiences but with that time put is come quality work out
Would you recommend this?
Yes, I would recommend to a friend
worked great
worked as advertised checked for run out on lathe .. none !!! lapped by hand and had no problems
Works for a true barrel bedding.
I trued up five upper receivers, four new and one that I had to remove the barrel from. I agree that the nub of a shank that you attach the drill to is too short. I did have some slip on the shank. None of the uppers were dead true. I trued two that had been cericoated and was impressed with the hardness of that finish. This tool makes me feel that the assembled upper is going to be as accurate as possible for the components used.
Worked well
I was hesitant to use but it worked well. I used 220 grit instead of the recommended 160 grit and it grooved the grinding surface of the tool. I will not exceed 5 seconds intervals next time and creep up on it even slower. It took three passes. Next time, I will try 600 grit that I have. I did stop at the @80% surface contact that Brownells recommended and I would not go any further. I followed all sorts of guidelines after watching many videos and instructions. I will use this again but the tool will have a limited life if the the surface contact area keeps wearing. I had never lapped something before and started out by hand but ended up using a drill without issue. I trimmed an Aero Precision upper without issue.
It works....., but
This tool works well, is straight and well machined and when price is factored in it is an overall good value. That being said I would pay more for something that would last longer. I have only lapped one very cockeyed upper and there is already a groove forming on the face of the lapping journal. And get rid of that round snout for the drill. Make it hex shaped for the obvious reason! For those bent on using a drill it will still work just fine. I would still buy it but will have the above caveat if I were asked about it by someone.
Good, but could use improvements
I purchased this to see if it would improve accuracy in my AR (6.5 Grendel). I used this on an Aero Precision upper, and surprisingly enough, it was pretty square. It did however square the receiver (as seen by the removal of material). I can't say that my rifle went from field grade to super match, but a little accuracy could be seen. My biggest complaint is the area where the drill is chucked. After use on 2 receivers, it slipped 4 times, requiring it to be re-chucked. When I finished, I noticed that the metal had actually deformed on the tool (where the drill chucks) and marred it pretty good. I think if it was shaped into a triangular shape, the grip would be better and it would last a bit longer.
