Brownells Upper Lapping Tool?

[spife7980]

Not much returning in search
I see people saying to send the upper off to be trued but does any one have any experience with the brownells tool doing it themselves? I have a demo bcm upper that Im putting together my first ar with and wondering if anyone has any reason not to. I cant think of any reason it would hurt.

https://www.brownells.com/gunsmith-...16-upper-receiver-lapping-tool-prod20220.aspx

 

[JZimm9mm]

I have used the Wheeler equivalent tool to fix a problem I had where I could not get the proper torque on the barrel nut while getting the gas tube notch to align. Unless you discover that your barrel is not centered in the hand guard (assuming the barrel extension is installed correctly) or have a problem with the barrel nut as I did I don't know why you would do it. Be aware that removing the anodizing and aluminum from the front of the receiver may get you a barrel nut torque problem that you didn't have originally.

 

[snbyiggidy1]

I have used the Wheeler equivalent tool to fix a problem I had where I could not get the proper torque on the barrel nut while getting the gas tube notch to align. Unless you discover that your barrel is not centered in the hand guard (assuming the barrel extension is installed correctly) or have a problem with the barrel nut as I did I don't know why you would do it. Be aware that removing the anodizing and aluminum from the front of the receiver may get you a barrel nut torque problem that you didn't have originally.

Great info. I have also looked at these several times thinking maybe it was worth trying to get better consistent accuracy. In the end I decided that sub MOA at 100 yards was good enough and messing could possibly cause more issues. Glad to see that maybe that was the right choice.

 

[mheimer_45]

Sent you a pm, spife.

 

[axarob44]

I have the Brownells version and used it a couple times no problem. Be careful and make sure you keep the lapping compound from migrating to the inside of receiver. Also, those BCM upper receivers are made a little tight in the extension/ threads that accepts the barrel extension. They recommend heating it up to slide the barrel in. Don't know how that will effect the lapping tool being able to spin freely.

As far as problems with the barrel nut, I don't see how lapping would cause any trouble. The barrel not just sandwiches the two surfaces (front face of rec, and the back face of the the bbl extension flange) together. the barrel nut moves on the front face of the bbl. extension flange. Plus, it's not like you're machining the face, removing a bunch of metal. Take a look where they meet (rec. and rec ext)

 

[flyer]

I saw Primary Arms has a good deal on the LR308 version and Optics Planet has a good deal on the AR15 version (or vise versa). Both Wheelers.

I need a couple cheap ones to turn down for use in Aero M4E1 and M5E1 enhanced uppers...

 

[wilsoncs3980]

The Wheeler I bought was total crap. The run-out on it was worse than the receiver. I'd get a Brownells or G&G Rifle Works. They do work well. I lap and bed all my builds. I only bed if the fit of the barrel is loose in the receiver.

 

[SharpsNitro]

I have the Brownells tool, I bought it a few years ago to try and solve an accuracy problem. Tool works as advertised, the face of the upper was not quite square and the tool solved it. The lapping compound migrats, make sure you fully strip the upper and keep flushing it as you go to prevent abrasion inside the upper. Also, clean it really well afterwards to get the grit out.

 

[flyer]

The Wheeler I bought was total crap. The run-out on it was worse than the receiver. I'd get a Brownells or G&G Rifle Works. They do work well. I lap and bed all my builds. I only bed if the fit of the barrel is loose in the receiver.

For $17.99 each, and because I'm going to cut them down on a lathe any way, I don't mind making a little clean up cut on the lapping surface.

It's still a lot easier than making a jig to lathe turn an upper and I can use them when I don't want to bother going to the shop.

If I were really concerned with getting things perfectly square, turning the upper is the only way but lapping is probably good enough (if the tool is square).