AR Upper Lapping Tool

[caulfieldian]

Anyone in central Indiana have one of these? I usually don't lap my uppers but figured I'd give it a shot with my next build coming up.

Basically all I'd need is to show up with my drill (and some lapping compound if you don't have extra) and use it for a few minutes, max. I could toss a few bucks your way for wear, tear, and materials. Not sure a 35 dollar part is all that worth it for curiosity's sake.

 

[Mgderf]

Thought about fire-lapping?

 

[natdscott]

Fire-lapping the barrel is not what is in discussion here.

I do not have the tool, and I emphatically anti-recommend the use of one. The rifle does NOT need it, and doing so removes the outer hard-anodized layer that makes it durable, and durable is safe.

Don't.

 

[caulfieldian]

Yea, I've heard many reasons for and against doing so. I was just curious. FWIW, it's a nickel teflon upper.

 

[natdscott]

Is it aluminum underneath?

Same result.

I work with some of the best AR smiths the world has ever seen, and NONE of them lap the upper.

 

[caulfieldian]

I'm trackin'.

 

[Dog1]

I was given one of those tools and when I looked at I said WTF?

Taking the anodizing off? Nope.

As natdscott said, you don't need it.

 

[Hookeye]

There is a tool that laps the face of the threaded area. For alignment a section does go inside the receiver and if using a drill can take off some anodizing.
By hand it will take longer, and probably only abrade the thread face.

One can also use an arbor that doesn't spin, and clean up the face using a different method.


I wonder, if a person removed anodizing inside the receiver, how they could go about restoring the surface finish (maybe cerakote?).
It's an AR................run the sheite out of it until everything is shiny.

 

[midget]

Removing the anodized face of an upper receiver where the barrel extension matches with the receiver does not make a difference in the receiver's longevity or effectiveness. The hard anodizing process is designed to reduce friction wear and not change the compression strength. This is not a high friction point, and in fact should stay mostly static aside from some insignificant deflection when shooting.

The face of the receiver should be square from the factory and as such should not need to be lapped. However, it is possible to get an upper receiver that is not true. If this is the case, then the barrel extension will not seat against the receiver properly, resulting in less than ideal surface contact. This can lead to accuracy issues. This is not a common problem though.

 

[Psode27]

I think if you buy quality stuff its more hypothetical than anything else. I have a hard time thinking that any decent company would let an out of spec upper (at least out of square barrel hole-don't know what thats called....) leave the factory.

 

[BIGE7.62]

Squaring a receiver is part of making a bolt gun more accurate . So why not the AR ?
Like midget stated it ensures the barrel extension sit s flush/square to the receiver . Also helps the bolt lugs engage more evenly

 

[j706]

Anyone in central Indiana have one of these? I usually don't lap my uppers but figured I'd give it a shot with my next build coming up.

Basically all I'd need is to show up with my drill (and some lapping compound if you don't have extra) and use it for a few minutes, max. I could toss a few bucks your way for wear, tear, and materials. Not sure a 35 dollar part is all that worth it for curiosity's sake.

I live just west of you and you can borrow mine

 

[BIGE7.62]

oops forgot
Im south of indy . I have one also, send me a PM if you want

 

[Hookeye]

Some barrel nuts take a bit of oomph to align.
Removing a bit from the front should drop your torque to middle of the spec.
In lapping the face, some abrasion may happen in the receiver, due to the pilot spinning.
How much, dunno.
Don't care either.
Not an issue IMHO.

 

[j706]

If you take a brand new upper and then use one of these lapping tools you just might be amazed at how smooth your AR15 will operate. I have a couple of AR's that feel like they are running on roller bearings. I like that. Keep in mind that these tools will also take off high spots inside the upper on the bolt assembly running area. It is required ? Probably not but it sure doesn't hurt anything and it does not take long. It is a rare upper that after using this tool you do not find a high spot someplace.

If you want a glassy smooth operating AR then use a lapping tool on your new upper, buy a bolt assembly with a smooth finish and buy a chrome silicon buffer spring. It will amaze you every time you run the bolt.

 

[Guncraft]

Caulfieldian, I understand about wanting to tinker the last bit of accuracy out of a firearm and we should probably start a support group... What is it that you are hoping to gain by lapping the upper mating surface?

Andy

 

[seedubs1]

People square/lap the receiver face so that the barrel extension sits perfectly flush with the receiver, and so the bolt aligns perfectly.

Problem is.....you aren't really going to get the kind of tolerance level you're looking for by chucking some tool from Brownells into your drill. To do it right, you need expensive equipment. Honestly, your money is better spent elsewhere than on that Brownells receiver lapping tool. You probably won't mess up your receiver by using that Brownells tool, but you won't gain much (likely nothing at all gained) either if you are starting with a decent receiver. You'd have to have a really out of spec receiver to have that Brownells lapping tool truly benefit to where you'd actually see a difference on the paper that's down range.

Point is.....by the time receiver lapping is really needed, those types of shooters and gun smiths aren't chucking a lapping tool into a drill to square up a receiver face.

Caulfieldian, I understand about wanting to tinker the last bit of accuracy out of a firearm and we should probably start a support group... What is it that you are hoping to gain by lapping the upper mating surface?

Andy

 

[Guncraft]

Seedubs1, I apologize for my poorly worded reply. I was asking Cailfieldian what he thought he would gain by lapping the surfaces. Maybe put a better way, what tangible improvement (whether function, reliability or accuracy) enhancement is he hoping to achieve.

Thank you!

Andy

 

[seedubs1]

All of the above. When things are better aligned, you decrease stress and increase smoothness, reliability, and repeatability.

But like I said, you aren't really going to get that by chucking a lapping tool in a drill. The tolerance level you'll achieve won't really gain you anything.

Seedubs1, I apologize for my poorly worded reply. I was asking Cailfieldian what he thought he would gain by lapping the surfaces. Maybe put a better way, what tangible improvement (whether function, reliability or accuracy) enhancement is he hoping to achieve.

Thank you!

Andy

 

[caulfieldian]

Guncraft, it was more a curiosity thing than any real need. I use aero precision upper receivers and I'm pretty sure they're all to spec and properly square. I just was thinking of trying something for the "why not" build I just completed.