Gunsmithing Muzzle device not threading all the way in

[stello1001]

Hello everyone,

Do you know of any quality shims I could use to get my muzzle device to sit flush? I removed my Lil B and going with Area419 hardware in order to use my suppressor and brake as needed/wanted. The APA Lil B would go in all the way. It appears my threads might be a tad bit too long and the Area419 adaptor does not make contact with the shoulder.

If someone knows of a particular product for these issues I would appreciate a link. Or is that a big No and and I should cut threads a bit?

I posted a picture and as you can see I can get paper to fit between.

Thanks,

S

 

[hlee]

Accu-Washer® Muzzle Device Alignment System

Precision Armament Accu-Washer Muzzle Alignment System - accurately index muzzle brake, flash hider, suppressor, compensator with perfect bore alignment ...

precisionarmament.com

 

[loveha]

No relief cut on your threads. Barrel needs to go to smith for proper cut.

 

[iceng]

Relief cut. Common problem. Shims are a cheap way to fix it. Get it done by a competent 'smith. Should be quick and painless, and can probably time your brake at the same time (not that a419 need it).

 

[Dendro]

PM me your address & I’ll send you a few of the accu washers linked above, it’ll get you up and running.

 

[toader]

Get a proper fix with a relief cut.....

 

[Waorani]

Should have relief cut but Surefire includes a thick chamfered washer with it's suppressor mounts just for that purpose. Don't know if they're available elsewhere but recently noticed PMM has the 5/8 7.62 washers for $8 - https://www.parkermountainmachine.com/store/p113/Surefire_SCAR_17/MK20___Shoulder_Ring..html

 

[CaptNemo]

No relief cut on your threads. Barrel needs to go to smith for proper cut.

If you had access to a lathe, a slight counterbore will give you clearance to thread it all the way up to the shoulder.
My OEM Tikka Barrel didn't have a relief cut at the shoulder and a few minutes in the lathe solved the interference.
More than one way to skin this cat

 

[stello1001]

Thanks everyone for the suggestions. I have 3 rifles that I want some work done on. I have most parts but still missing a few. Once I have everything, I'll be sending them to a Smith for all the work. I will have a relief done to this one then. In the meanwhile I will take up @Dendro on his offer. I need to put something on the end of the rifle to serve me as a thread protector and I would prefer the muzzle device goes all the way back and makes contact.

 

[Hateca]

Don’t use shims and don’t start cutting a thing until you get a builder to look at that. If the shank is long for the the brake you removed, the Area 419 adapter could be bottoming out on the crown area of the barrel.

 

[Wannashootit]

Don’t use shims and don’t start cutting a thing until you get a builder to look at that. If the shank is long for the the brake you removed, the Area 419 adapter could be bottoming out on the crown area of the barrel.

That was my thought when I first came across the thread, but didn't comment.
Everyone jumped in saying there wasn't a relief cut, before the OP confirmed that was the case...sure can't tell from the picture he posted.
Relief cut or not, bottoming out on the internal threads is always a possibility that can be checked with the rod on a caliper for a rough depth measurement.

Happened to me more than once when the tenon spec didn't allow much leeway for an extra turn that might be needed to time the device, and setting the shoulder back bottomed out the threads at the muzzle end.

 

[stello1001]

I had not confirmed whether a relief cut was needed or not because I just automatically assumed my threads continued back to the shoulder. Obviously, that's not the case. I removed the muzzle device and realized that it does need a relief cut.

 

[spife7980]

That looks pretty shitty all around there at the start. Chop it and have someone not cross eyed thread it. Better yet put that 100 bucks to a new barrel.

 

[JBoomhauer]

That looks pretty shitty all around there at the start. Chop it and have someone not cross eyed thread it. Better yet put that 100 bucks to a new barrel.

Agreed. That almost looks like a die job...

 

[b6graham]

that thing is crooked as fuck

 

[stello1001]

I took some other pics because the first one is pretty blurry. Not sure how much better these new ones are though. I can't tell that the threads are bad (the last two threads near the shoulder aren't as deep) but they are somewhat dirty so they don't get the super shiny new look.

 

[vh20]

Sure looks like a die-job. But whatever, it just doesn’t look properly done.

 

[iceng]

That thread looks janky. Could most likely be your problem. Thread isn't square / fully formed / other issues. A good 'smith can chop that part off and start again.

 

[Wannashootit]

Looks to me like it was fully threaded to the shoulder, then whoever did it went in with a parting tool or groover and removed the threads for a "relief cut"- then perhaps extended it/set back the shoulder further time the brake correctly.

It's a pretty ugly job at the ass end- but I'll disagree in that I don't visually see anything incorrect with thread form. Maybe angle of the shot- top looks a bit "off", but the bottom crests look fine to me. If the Little Bastard had good thread fitment, and locked up to the shoulder correctly (no space anywhere at the shoulder junction) that's all that matters. Won't win any prizes for looks- but as long as the PD is correct and the shoulder is square the rest is cosmetic- and isn't visible. OP didn't report any issues with the brake- no accuracy issues, no bullet strikes. "Crooked as fuck" would've made itself evident with the first bullet down the tube.

I don't see any remnants of the threads near the shoulder, meaning the OD looks to be no larger than the thread minor diameter and the device should thread on to the shoulder. As I mentioned previously, I would check the depth (length) of the female threads on the new device and compare to the length of your tenon. I still suspect it may be bottoming out on the inside.

JMO

 

[Jigstick]

Dude don’t shoot that suppressed. Asking for baffle strike or worse. Pull that barrel and have proper threads cut. Hopefully it can be saved. May have to whack off an inch and get proper 5/8x24 threads done.

 

[Jigstick]

 

[stello1001]

My suppressor is with my dealer and I suspect I got two more months to go, maybe three. As said before, I have a some work that needs to be done to my rifles so sending them to a Smith soon. I'll make sure the threads get looked at.

In person they do not seem crooked but I agree they look bad in the pic. Maybe they're off a tad bit that it's difficult to see in person. Either way, the Lil B had a great fit, it's only the area 419 stuff that I'll shim temporarily until it goes in for work...