AR Barrel Thread issues...HELP

MCP

MCP

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HELP ME!!!!
Here is the background story..... I have a Daniel Defense Stock 16" rifle (DDM4V7 LW) that is a little over a year old. I wanted to change the standard flash hider to an S&J linear comp that I purchased from my LGS. I removed the flash hider with no issues. When I went to put on the new Linear comp it went about 1.5 turns on and then binds (hand tightening). I re-tried my stock flash hider and I can hand tighten it no prob. I figured the comp may have been out of spec so off I go back to the LGS, and I brought my upper for ####s and giggles. Here comes the problem I need help with.

We tried numerous comps and they all do the same thing, 1.5 turns and bind. We tried the same comps and my stock flash hider on a different barrel they had in the store and they all hand screwed on. We measured TPI with a gauge, we measured barrel size and its in spec (1/2 28 TPI). If you look at the threads they all appear good, however the first thread may (we couldn't really tell for sure) be folded over a little bit. It appears shinier than the rest and we couldn't really tell. The LGS and don't think this is an issue, since my flash hider still screws on without a problem.

How do I confirm this thread isn't bad.....and if it is, how do I fix it. Is there a way to remove the first thread, or do I have to have the barrel re-threaded. Any other hints from you wise CGNers?

Or worse do I have to tell my wife that I need to purchase the shorter barrel that I have been asking for all along.

I am hoping to not have to trash this barrel as it only has maybe 600 rds through it.
 
I highly doubt the barrel threads are the issue. Did you actually try noumerous BRANDS of comps, or just more of the same comp?
 
Hmm, I recently installed the S&J comps on a couple of my ARs. They could not be hand-screwed, so I used an AR tool to tighten. Don't think those are going to work loose any time soon, and I didn't have to use any loctite. Never thought this was an issue, just assumed that the tolerances were really tight in order to prevent the comps from loosening with repeated firing of the rifle.
 
I don't think even a wrench would get it to go without seriously torqueing on it...... and we only tried the same comps (mine that I had bought and another from the shelf and of course my A2) both S&J Nano Linears
 
I bought an S&J comp about a year ago and the threads on it were buggered up - same issue as you had, and didn't notice until inspection of the threads upon failure to properly mate up with the barrel.
I would not force it on a barrel as that is a good way to ruin both items.
 
Chase it with a 1/2x28 QUALITY bottoming tap..This will clean out any Parkerizing that is done after the original threads were cut...This is all it may be..Do not forget to use assembly lube or Never Seeze and hand fit..Then take it all apart once the parts screw together nicely..Brake clean and apply the thread lock of your choice..Good luck.

Rob
NTC223
 
Thanks....I knew that there would be some good ideas......as for buying taps, does anyone have any specific info on where to get them without breaking the bank. Does it have to be specific for gun smithing or will any tap do?
 
any tap is fine, you're just chasing the thread but still use lots of oil and back the tap off once in a while to clear any debris (should be minimal though). If you want a good one I'd look into KBC Tools but Im not sure what shipping would be like. Also, it won't matter if you use a taper or a bottoming tab because it isn't a blind hole, but a bottoming tap will ensure all the threads will be cleaned. Cheers, good luck!
 
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If you don't have a tap you can put the FH in a vice a run a bolt of the same thread with lube through it a few times. Probably extra Parkerizing or paint on the threads.
 
...and if the threads were not cut right in the first place like mine, you could be causing further issues with the threads by chasing it with a bolt or tap.
No offence to S&J (everyone has Mondays), but there should be zero issues exchanging it for one that is squared away.
You might have a harder time with that process after you have attempted and failed at a fix.

....just food for thought.
 
Op im on the road today
let me touch base with you tomorrow
a year ago we were using a tap
now we machine cut the threads
we also use class 3 thread pitch
so if the thread is good on the Barrel then no issue
that said you mush degrees the comp before trying to screw t on
when finish is applied some residue gets left from the finishing oil
 
beltfed said:
...and if the threads were not cut right in the first place like mine, you could be causing further issues with the threads by chasing it with a bolt or tap.
No offence to S&J (everyone has Mondays), but there should be zero issues exchanging it for one that is squared away.
You might have a harder time with that process after you have attempted and failed at a fix.

....just food for thought.
Click to expand...

I did exchange it at the LGS and brought my upper in to make sure the new one fit......same thing with the exchanged one. We tried them on my barrel and it didn't work, tried them on a barrel they had in the shop and no issues. Further to my original post, I inspected my barrel threads closer and they are fine. I will await your msg BBB.
Thanks
 
MCP said:
I did exchange it at the LGS and brought my upper in to make sure the new one fit......same thing with the exchanged one. We tried them on my barrel and it didn't work, tried them on a barrel they had in the shop and no issues. Further to my original post, I inspected my barrel threads closer and they are fine. I will await your msg BBB.
Thanks
Click to expand...

Yeah, I got that from your first post.
I guess my post wasn't just aimed at your particular situation, but as a generality.
 
Sorry op, I guess I more scanned your post than read carefully therefor my previous post is useless. If measuring the pitch and diameter of the barrel threads is correct and your comp fit fine on other barrels at you LGS then you are probably right about the first thread or two being a bit buggered. Maybe run an appropriate die and chase the barrel threads...just make sure not to cross thread the die...then you'd be right f###ed
 
Bobbum Man said:
Sorry op, I guess I more scanned your post than read carefully therefor my previous post is useless. If measuring the pitch and diameter of the barrel threads is correct and your comp fit fine on other barrels at you LGS then you are probably right about the first thread or two being a bit buggered. Maybe run an appropriate die and chase the barrel threads...just make sure not to cross thread the die...then you'd be right f###ed
Click to expand...

No problem....the threads are ok after closer inspection.. I can only assume that it is too tight because of the finish on the comp. I am waiting to here from s&j.
 
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