AR Receiver lapping tool

[rushta]

Anyone in SoCal have one of the lapping tools for truing the receiver face on an AR15 upper? Like the Brownell's or Stoner one from Midway? I'm getting the rest of my parts in this week to build my new AR and I was wondering if anyone has the tool.
Thanks,
Mike

[SJgunguy24]

I don't realy think that's a good idea to do with anodized aluminum.

[VaderSpade]

I've built 20 AR's and I've never heard of this tool?

It must not be necessary??

[freonr22]

googling found this

Building An Accurate AR-15 Group Therapy
The best time to accurize an AR is while building it, but going back and tweaking an existing rifle or carbine isn’t that difficult. Here again, having a few specialized tools makes the job easier. The two tools I use most often are a receiver lapping tool and muzzle crowning/re-crowning tool set. The lapping tool allows you to “true” the front face of the upper receiver, seating the barrel extension squarely and theoretically aligning the bore with the upper receiver. In this case I’ve found that theory follows practice. I have yet to encounter an AR that hasn’t tightened up noticeably after truing the receiver. In a couple cases this procedure changed 2 MOA plinkers into 3/4 MOA shooters. That’s quite dramatic and makes me wonder where the poor tolerances exist: upper receivers, barrel extensions, barrels or some combination. Care is required to prevent damaging the receiver, as the lapping tool must be well lubricated to prevent “burning” of the inside surfaces of the upper receiver. Commercially available lapping tools have a relief groove to prevent lapping compound from getting inside the upper receiver and removing metal from the wrong places.
Steve Adelmann is a former SOF sniper with 21 years and 10 combat tours of duty in the US Army. He owns Rifleman Consulting, helping freedom-loving US citizens through writing, advising and AR-style rifle customization services. Go to: http://www.riflemanconsulting.com for more information.

http://www.longrangehunting.com/articles/building-accurate-ar-15-3.php

[rushta]

Its not critical to do this but it certainly doesn't hurt. All my prior builds have been with as delivered uppers. This one is special though. Some say it really doesn't matter because the bolt will lock up in the barrel extension regardless of the barrel to receiver relationship but having the receiver and barrel on a single centerline should help with wear, smooth operation, and having optics in closer alignment with the bore before zeroing. It may help accuracy too. Not necessary to shoot it but neither is truing a 700 bolt gun for precision work. Some may shoot great without it. Doing it offers potential improvement when receivers are not always made perfectly.
Thanks,
Mike

[freonr22]

who's upper receiver are you getting?

[VaderSpade]

Sounds like it may be worthwhile for a rifle that has poor accuracy, but every one that I’ve built with a 20”-24” barrel will shoot under 1 MOA when you find the right load (the most important factor in accuracy). The one's I’ve build with 16” barrels shoot within 2 MOA.
It may be easier to lap while building, but I think I would wait until I had a problem. That being said I will keep this in mind if I ever have accuracy problems with a new build.

[rushta]

Im using a DPMS Lopro upper reciever. Before I get any DPMS hate its the only DPMS part going into this build. Its the same receiver White Oak Precision and Robert Whitley use on there championship winning Match rifles. Much thicker than a standard A4 upper, no forward assist and dirt cheap. Whitley mills them to make side chargers out of them, and suggests while generally they arent a problem occasionally truing the face makes a big difference.

The barrel is a White Oak Armament DMR barrel with a 1 in 7 twist. Ive had cheap M&A uppers group around 5/8ths with handloads at 100 for 5 rounds (off a bench with some consistency) so this one I'm hoping 1/2 or better. I pretty much only shoot handloads.

Im going to be loctiting the extension into the receiver so I'd rather do it now than later...

[wash]

I know of one AR smith that trues the front of the upper in a lathe. I asked him about the Brownells lapping tool and he said it's the way to go if you don't have a lathe.

I didn't know Stoner made a lapping tool but I bet it's pretty much the same thing.

He also does the locktite which is something I want to research (to determine break away torque).