What lapping tool do you guys use at the shop?

I have the wheeler tool. It’s cheap but works fine.

Not sure if it was spelled out but ‘gluing’ the barrel in is more like bedding than gluing. The locktite goes between the barrel and receiver. Grease/ anti seize still goes on the threads.


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Right (IMO) I get that. So which locktite? The Green stuff. Didn't I read in another thread here on WaGuns that the green stuff can bridge/fill several 1000th of an inch?

I don’t know. I’ve never done it

The red stuff is pretty solid, till it gets hot. I’m sure any form/color of it turns to goo once the barrel warms up


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People constantly use the wrong “stuff” for the wrong reason.

I have a 1911 “on my bench” that someone decided to use a green loctite on the rear sight. It covers the entire bottom of the sight and nothing was left in the dovetail once I removed the sight. Wrong application of that product. I had to beat the life out of that sight without damaging it.

Thread locker is not bedding.

Anti-Seize in some form needs to be on the barrel extension or the inside of the receiver. It’s easier to put it around the barrel extension in my opinion but, why not do both for that smooth flavor.

Green 680 is the stuff to use. It cures in up to .015" air gap IIRC, and definitely counts as "bedding" for an AR upper. For an accuracy build, that's what I use along with truing the upper, or else use a shrink fit BCM upper. No bedding required with those since they end up as a more solid connection anyway.

For guns that are not specifically a long distance accuracy gun, I just true the upper and install everything with antiseize.

An upper bedded with Loctite or epoxy of any type is still able to be disassembled with heat though. It's not a big deal to take them apart, but it does require more heat than it'll see in any reasonable actual use.

Agree.

Did you heat it? "Green" Loctite, is the weakest of that variety.

Yes, I did warm it up a bit although it was not in consideration for Loctite. Just warming things up a bit helps them move a bit easier. I observed the substance was present after the sight was removed.

I don't lap the receiver. I have a fixture that I use so I can cut the face on the lathe. Many upper receivers are good, but I've had some not be square. If you ever get an upper that doesn not shoot well I recommend an inspection/truing of the upper receiver

No, you're probably thinking of purple Loctite.

There are several grades of Green, and they are all some sort of bearing/sleeve retaining compound, not threadlockers like red, blue, and purple. The 680 Green I mentioned above is one of the highest strength Loctite compounds.

You do have to get them more than just "warm" to break down the bond though. Typically ~400-500 F will do it, which will turn steel colors somewhere between yellow and brownish-purple.

No, I wasn't thinking of purple.

I was thinking of the Green wicking variety. But calling it by color is not precise obviously. The "green" wicking variety available for home type use (no idea what that guy used though) is not very strong, maybe a bit weaker than purple on threaded fasteners. The retaining compounds, I agree are quite strong.

I had a buddy claim to get his low end DPMS to shoot a LOT better after truing the front of hte receiver. It helps ensure the barrel is straight and even. That makes sense.

Using Loctite to glue a barrel in does not. Loctite cures in the lack of oxygen. Interesting trivia, it's not the Loctite itself that is so expensive, it's the plastic container that allows oxygen to pass through so it doesn't cure. If the barrel to receiver fit is so loose that it would need bedding or glueing, then it's too loose of a fit for the Loctite to cure anyway. So it's kind of pointless.

Have you ever used or researched the different grades of green Loctite sleeve retaining compounds? #680 cures in up to .015" air gap, which is far more than even a very loose AR receiver will have. Another grade can handle .005" which is still plenty.

Even blue 242 Loctite will cure most of the time in a loose receiver. If you've had an actual experience where it didn't work, it must have been a very loose one, or poor surface prep.

This discussion of locktite is pedantic. That process is never going to overcome the limitations of the platform

Slamming a round up a feed ramp and into the chamber will offset any advantage you may get from tightening the barrel extension to upper receiver fit. If the upper is really that sloppy you should be shopping in better places

If you get to the point where the barrel harmonics are a concern with respect to accuracy then you’re probably hand loading for it and have moved well beyond what we are talking about here