What to do when the barrel nut is either too loose or too tight?

[Tim K]

On the first few uppers I put together, it seemed like the barrel nut always timed out just where I wanted it. On the last few, (including the one on the bench at the moment), the nut is either too loose or too tight. In most cases, I can kill it and get it lined up on the too-tight side or, of course, leave it what feels to be too loose.

I'm embarrassed to admit to not owning a torque wrench that size, so I don't have numbers to go along with my subjective feel.

It seems like facing off the front of the upper a few thou would be a relatively simple solution if I had a mill. Is there some trick I'm missing?

[Hoser]

It seems like facing off the front of the upper a few thou would be a relatively simple solution if I had a mill. Is there some trick I'm missing?

PM sent

[Tim K]

Perfecto!

[bobbyfairbanks]

What was the trick?

[Tim K]

What was the trick?

http://www.brownells.com/gunsmith-tools-supplies/rifle-tools/receiver-tools/ar-15-m16-upper-receiver-lapping-tool-prod20220.aspx

[Alpha2]

NOW I find this info...

Next time will be easier! My last three builds had the barrel nut exactly half way between one hole and the next, too little torque for one hole, right at the max at the next.

Oh, and get a torque wrench, they're not that expensive.

[Hoser]

Oh, and get a torque wrench, they're not that expensive.

Keeping them calibrated is expensive though.

[ray1970]

Keeping them calibrated is expensive though.
As little use as it would probably see, might not be much of a concern.

I use them every day and have them calibrated once a year. They are seldom very far off. Seems the 3/4" drive and 1" drive ones are the worst. But I'm really rough on them too. They get dropped ocassionaly, banged into stuff, and see thousands of miles a year riding around in a utility box on a truck.

I imagine using them gently to torque barrel nuts and even building twenty or so a year probably wouldn't be much need for any calibration for many years.

Just my two cents.

I realize everyone has a different level of OCD about stuff.

[sportbikeco]

If you don't have a torque reading on it you don't know if it is too tight or too loose.....

[Tim K]

If you don't have a torque reading on it you don't know if it is too tight or too loose.....

Of course I do. I may not have exact numbers, but it have 40 years of experience swinging wrenches on cars, motorcycles, and aircraft. I don't have one in the correct range at this precise moment in time, but that's not to say I have never owned or even used one. I absolutely know if it's too tight or loose, I just can't give a precise number.

[Irving]

Wow, great info. Learned something new today.

[BPTactical]

For future reference Spikes makes barrel nut shims to time a pesky nut. They are really handy for nuts that are proprietary. For standard nuts if I get one that won't time in a decent torque range I use a different nut.
Ray is on the money for wrenches, as long as they are not mis used they keep an accurate torque for a long time.
Always back the wrench off to its lowest possible setting before storing it.

[Great-Kazoo]

For future reference Spikes makes barrel nut shims to time a pesky nut. They are really handy for nuts that are proprietary. For standard nuts if I get one that won't time in a decent torque range I use a different nut.
Ray is on the money for wrenches, as long as they are not mis used they keep an accurate torque for a long time.
Always back the wrench off to its lowest possible setting before storing it.


AND put some lube NOT Loctite on the receiver threads.

[Tim K]

For future reference Spikes makes barrel nut shims to time a pesky nut. They are really handy for nuts that are proprietary. For standard nuts if I get one that won't time in a decent torque range I use a different nut.
Ray is on the money for wrenches, as long as they are not mis used they keep an accurate torque for a long time.
Always back the wrench off to its lowest possible setting before storing it.

More great advice. Thanks.

[Tim K]

The linked tool worked perfectly, and very quickly. I put a little lapping compound on the surface and ran the drill for 5 or 6 seconds at a shot. It took 3 treatments to get it right, but it's perfect. It took far longer to try the fit after each treatment than it did to actually do the work.

Highly recommended.