truing an AR upper face (Read 495 times)


truing an AR upper face
« on: April 18, 2022, 05:49:27 PM »
anyone do it? thoughts?
Deeds Not Words


Re: truing an AR upper face
« Reply #1 on: April 18, 2022, 07:53:24 PM »
Yes, on my .308.   Had been having erratic grouping and truing the face along with shimming the barrel were to tighten things up and take away possible reasons for wandering shots. 

I could see some high spotting taken down as I did it.  Of course, doing the shimming at the same time blows away any way of telling which thing improved things, if anything.

Go very slow, once through the anodizing, metal is removed fast.  It will alter your gas tube timing if much is removed as the barrel nut will turn a bit further.
I ordered some barrel shims to fine tune the alignment and avoid insane torquing.

Yet to mount the scope and go for groups, but casual shots while tuning the gas block were promising.  Set a target out about 47 yards to have an aiming point, and started getting serious after a few casual shot.   Open sights off a portable shooting bench.  Sun was behind me and I had a hard time getting a sharp aperture with the sun on it.  POA was the bottom of the 3" bull.   Did not try and adjust the sights.  Eleven shots, not bad for casual iron sight plinking. 

Not going to do the mousegun until I have reason to suspect things.  The el-cheapo PSA SS barrel does not lead me to expect much.
« Last Edit: April 19, 2022, 08:53:53 AM by robtmc »


Re: truing an AR upper face
« Reply #2 on: May 29, 2022, 05:59:31 PM »
I do it for all my AR builds.  yes, worthwhile.


Re: truing an AR upper face
« Reply #3 on: May 29, 2022, 07:22:55 PM »
You know about my 5.56mm AR barrel issues.  Did not have a truing tool for the mouse size ar, so just ordered one.  Shimmed the barrel only.

I do not expect a barrel with messed up throat rifling to be fixed by it, but when I put a known good quality barrel on, the receiver face will be true to the bore.

A buddy with a lot of machining experience did not believe in it, insisting the tooling used was too good, but did it anyway and something stopped the flyers that opened up groups.

Some machinist could make some $$ by coming up with a convertible facing tool to fit both size AR receivers.   Some sort of diameter adapter sleeve I suppose.