308 DPMS barrel nut; Do I just need to really torch this half too?

[VaniB]

This is an old photo from a few days back: I've already got the DPMS 308 round FF handguard "Part A" removed. Now I have part B to remove.

I already tried locking it in my DPMS delrin block and vise, and using the torch on it. But it still would not budge. Is there a pin or some part in that "B" half that I don't know about holding it in place?....... or do I just need to heat it some more to burn off some factory loc-tite and try again with putting more muscle behind that wrench?



http://i25.photobucket.com/albums/c54/hobbyguy/DPMSHandguard.jpg

[Lostinthewoods]

Obviously you've removed your gas tube.......

Get some Kroil or other good penetrating oil, soak it good and let it set overnight.

If they have red locktited that puppy on, it takes about 350 degrees to soften it up, wrap a wet towel around your barrel and upper to try and keep the upper threads as cold (shrink) as possible when you heat (expand)the nut.

I'd keep the torch away and use a good heat gun instead.

If (shudder) they didn't use locktite or lube the threads properly, it may have galled together.

Heat it up and screw it off is all you can do, unless you don't care about reusing the bbl nut, then you could use a dremel tool w/ cut-off wheel and cut some slots around the nut (parallel with the barrel bore to relieve the tension, but be careful and don't get into the upper threads).

HTH

[SHIVAN]

Based on your posts from AR15.com, at this point I would send the upper back to DPMS and request they un-screw the parts. Especially since it looks/sounds like they used red loctite on it.

[VaniB]

Based on your posts from AR15.com, at this point I would send the upper back to DPMS and request they un-screw the parts. Especially since it looks/sounds like they used red loctite on it.

I didn't want to have to make photo updates as I progress along in this project..... but as mentioned in my opening post, I already have the handguard removed.

The 1 week it takes me to figure out how to strip it down in order to install my new 18" Fulton barrel, beats the 4 to 6 week wait and charges sending it off to DPMS or Fulton. Not to mention that as of the Obama era, most service companies that accept our business act as though they are doing us a favor.

The tools bought (including the 36" spanner wrench I made and showed in my ARFCOM thread), and the knowledge gained thus far is invaluable for future projects that I intend.

Thanks.

PS.....I suspect that when Obama is finished screwing us with his socialized medicine pet project......Obama, Holder, and Pelosi will mention "A.W.B." and start another year long panic. I'm doing my buying NOW......and my learning.

[SHIVAN]

Judging by how much effort you spent already, I figured that would be the reply. :D

At some point, you need to decide which part is sacrificial.

I've busted out the dremel and cut the barrel nut off, castle nut, etc off before just because I wasn't going to risk torquing an M16 registered receiver in a vise block.

While the DPMS is no M16, it would still suck to apply all that torque, or heat, or both to an aluminum upper and ruin it versus ruining the cheap part and saving the hazard and the time.

Good luck.

[ADC]

I have had to throw some of the DPMS 308 uppers in the milling machine and mill the barrel nuts down to remove them, like shivan said get the dremel out.

[Robb Jensen]

I've removed a bunch of DPMS 308 FF tubes. Most require a ton of heat and I use a small pipe wrench to remove the bbl nut. It ruins the nut but it's not being reused anyway.

[Quib]

Would the freezer trick work?

[Robb Jensen]

Would the freezer trick work?

Probably not since both the bbl nut and upper receiver are aluminum. If they were different metals that trick would very likely work.

[VaniB]

I completed this about a week ago. Some of you may have seen that I posted a thread asking about the next job concerning FSB installation.

I ended up cutting the barrel nut down thin with a Dremel cutting wheel and popped it off with a large flat head screw driver. I was hoping to be able to save the barrel nut so I coud resell it with the other half of the handguard. But, no biggie. Once I decided to give up trying to screw the barrel nut off and decided it had to go.....it was the usual simple extraction procedure for me that I've used many times in my work.

If anybody cares to know....there was no loc-tite, no galling, and the threads were wet with the fluid that I had put on it overnight!! Yet, with a torch and wrench it was NOT going to come off. (At least not with the 80 lbs of torque I tried).

Now I know what to expect in the future.

[Quib]

Probably not since both the bbl nut and upper receiver are aluminum. If they were different metals that trick would very likely work.

Ahhhh, that’s kind of what I thought. :(

I have no hands-on experience with that DPMS rail, but looking at the pics, I kind of had the feeling that the barrel nut was aluminum. Definitely no coefficient of expansion there.