Problem with Surefire muzzle device?

[Twilk73]

I am a automotive mechanic not a gun smith. So now that that is out of the way.

I started to hand thread the Surefire flash hider onto a POF barrel. I was test fitting it to see what shim we would need. The birdcage made it approximately three rotations by hand, no tool was used, it got tight and wasn’t even half on, so I went to back it off and it was stuck. This thing was so stuck I had my buddy hold the vice table down while I was turning it off with the wrench. I never touched it with a wrench until I needed to remove it. I’m freaking confused, being a mechanic this makes no sense, you don’t hand tighten something and now it’s so tight it won’t come off. Anyway we removed it and 1/3 of the threads are stripped on both the barrel and the birdcage. It looks like it was cross threaded. I’ve cross threaded plenty of bolts, as a mechanic it’s just part of the job, mostly in the early years and when you get complacent from rushing.

Anyway, initial thoughts are it was cross threaded but to me that makes no sense, I only put it on with my hand, it felt a tad snug but not bad until it just stopped. Then it barely removed with tools. I used a gauge and the remaining threads on the barrel are in fact 1/2 x 28. I couldn’t really gauge the birdcage. So knowing the POF barrel threads seem ok can I assume the birdcage was not ok. Outside looking in, this looks like I cross threaded it and it would be hard for me to prove otherwise. However, I’m not the hulk I’m average Joe I don’t see how I cross threaded it three whole turns by hand.

Can adco or someone else re threads this without cutting it? I might be able to re thread the barrel myself actually.

Thanks for your input.

[17K]

Sounds like there was burr or chip that got jammed in the threads when you hand tightened it, and it mangled up the threads when you hulk smashed it off. Not much else you could have sone at that point.

[Twilk73]

Sounds like there was burr or chip that got jammed in the threads when you hand tightened it, and it mangled up the threads when you hulk smashed it off. Not much else you could have sone at that point.

Possibly, that would explain why it threaded on about three full threads before it got tight. I’m interested in all ideas. It doesn’t make a whole lot of sense to me.

[MegademiC]

I would chase the threads in the muzzle device to make sure they're clear/clean and correct thread.

If youre not mounting a can, 2/3 threads will be fine.

[Hammer_Man]

Did you clean the threads of the barrel and the flash hider before attempting to screw things together? There may have been a burr, or carbon fouling that decided to ruin your day. Always clean the threads with solvent and a brush before attempting to mount a flash hider. At this point, all you can do is chase the threads of both the flash hider and barrel and try again. Hopefully there’s enough thread left on both to torque down to no more than 30 lbs.

[Twilk73]

Did you clean the threads of the barrel and the flash hider before attempting to screw things together? There may have been a burr, or carbon fouling that decided to ruin your day. Always clean the threads with solvent and a brush before attempting to mount a flash hider. At this point, all you can do is chase the threads of both the flash hider and barrel and try again. Hopefully there’s enough thread left on both to torque down to no more than 30 lbs.

I did not clean, both were brand new and un opened. Lesson learned, I’ll try chasing them.

[GH41]

I am betting the barrel and MD are stainless steel and you assembled them dry. If either thread is at the top of spec it will happen more often than not.

[prepare]

Get a 1/2 x 28 die and chase the threads.

[OutofBatt3ry]

Get a 1/2 x 28 die and chase the threads.

Might as well get a tap now as well. One was out of spec before you started. After both are buggered up it's hard to say which one.

[Twilk73]

Might as well get a tap now as well. One was out of spec before you started. After both are buggered up it's hard to say which one.

I actually don’t think either can be trapped or threaded. I mean this mangled the threads so bad it took a lot of metal with it. The barrel might need to be shortened. It’s just so hard to believe this happened after only turning it in by hand.

[GH41]

I actually don’t think either can be trapped or threaded. I mean this mangled the threads so bad it took a lot of metal with it. The barrel might need to be shortened. It’s just so hard to believe this happened after only turning it in by hand.

Read post #7

[GH41]

Read post #7

And this >>> https://www.rg-group.com/resources/blog/what-is-stainless-steel-galling-and-what-causes-it

[Twilk73]

And this >>> https://www.rg-group.com/resources/blog/what-is-stainless-steel-galling-and-what-causes-it

Well the Threads look like that, so it’s likely what happened, plus I installed it dry as I was only trying to see what shim was needed. I’ve installed thousand’s of bolts and nuts and never experienced this situation but we don’t deal a lot with stainless steel. So next time use anti seize.

I know I’ve said this already but damn I only turned it on by hand lol.