Suppressor question re Barrel Threading

[Richard Jones]

I have one of those, too, and the connecting devices (one for each barrel) are spendy and create enough problems of their own that I would not go that route again.

If you are after maximum accuracy, I would not get a can you cannot easily disassemble for cleaning.

I'm probably going to regret this, but..............

Spendy relative to price of a can? No.

Create what kind of problems?

All my cans disassemble easily.

Back to the OP's question now. I would not send the can out and I think that most 'smiths recrown when threading the muzzle as a matter of course. You could always tell whoever to leave the crown as is if you're worried about it. But, if you don't trust the smith to recrown, what does that say about his threads?

 

[KY_Windage]

I'm probably going to regret this, but..............

Spendy relative to price of a can? No.

Create what kind of problems?

All my cans disassemble easily.

Back to the OP's question now. I would not send the can out and I think that most 'smiths recrown when threading the muzzle as a matter of course. You could always tell whoever to leave the crown as is if you're worried about it. But, if you don't trust the smith to recrown, what does that say about his threads?

They, too cause buildup on the crown, and make it hard to get to the crown to clean it. They also collect carbon themselves and you can end up with a can stuck on the connector.

While any good smith will want the can to try before he unchucks, we do agree on the crown, for the most part. Threading necessarily involves cutting into the crown (cutting part of it away) so at the very least you would want him to chamfer the outside edge.

But yes, if he cannot get the crown right I certainly don't want him trying to thread the thing. Comparativley, the crown is a piece of cake.

 

[Richard Jones]

They, too cause buildup on the crown, and make it hard to get to the crown to clean it. They also collect carbon themselves and you can end up with a can stuck on the connector.

While any good smith will want the can to try before he unchucks, we do agree on the crown, for the most part. Threading necessarily involves cutting into the crown (cutting part of it away) so at the very least you would want him to chamfer the outside edge.

But yes, if he cannot get the crown right I certainly don't want him trying to thread the thing. Comparativley, the crown is a piece of cake.

No, no, no.

"While any good smith will want the can to try before he unchucks,......." This is just not true.

Not sure why you continue to reinforce this mis-information.

 

[KY_Windage]

No, no, no.

"While any good smith will want the can to try before he unchucks,......." This is just not true.

Not sure why you continue to reinforce this mis-information.

Why? Because I know a guy who has been considered to be one of the top machinist/gunsmiths in country, and that is what he has told me.

And because, like I said, I have seen the results when a buddy got a very highly regarded machinist/gunsmith to thread his barrel, without having the suppressor because it was in another state, and then seeing him not be able to thread the suppressor on when we got to where the suppressor was.

And while the smith can always cut the threads deep enough to where you can thread the suppressor, flash-hider, etc., on to the barrel, there is a price paid for that sloppiness -- your device will shoot loose easier. It is absolutely foolish to have threads cut without checking the fit before the barrel is unchucked.

 

[carlsbad]

I always prefer to have the muzzle device (usually a brake) before I cut the threads. There are manufacturers all over the place making small lots and while it is easy to put "Class 2B threads" on your spec sheet, most don't actually meet that. If I am cutting threads and I don't have the device in hand, I will cut them as loose as possible to ensure that the device actually threads on.

It is important to cut the muzzle threads centered perfectly on the bore. I don't know this manufacturer's reputation but if they just throw it in a chuck and cnc some threads on the end, it will affect your accuracy since windage going through a not-perfectly-centered device will push the bullet. Unless you have good confidence in them, have them send you the brake and take it to a reputable local gunsmith to thread.

And as boltfluter said, use the biggest threads possible. I don't like 5/8 thread. I start with 3/4. For tuners I used .900.

---Jerry

 

[tobnpr]

Even after you have the suppressor in hand, you cannot legally leave it with your gunsmith for the threading job --

This is absolutely incorrect.

Any gunsmith- 01 or 07, can possess/work on customers' NFA items- even without a SOT.
BATFE recommends a Form 5 be completed, but it is not required.

Here:

https://www.atf.gov/firearms/docs/repair-nfa-firearms/download

And here:

May a licensed gunsmith receive an NFA firearm for purposes of repair? | Bureau of Alcohol, Tobacco, Firearms and Explosives

Yes, a licensed gunsmith may receive a National Firearms Act (NFA) firearm for the sole purpose of repair and subsequent return to its owner. It is suggested that the owner obtain permission from ATF for the transfer by submitting an ATF Form 5, Application for Tax Exempt Transfer and...

www.atf.gov

 

[tobnpr]

And while the smith can always cut the threads deep enough to where you can thread the suppressor, flash-hider, etc., on to the barrel, there is a price paid for that sloppiness -- your device will shoot loose easier. It is absolutely foolish to have threads cut without checking the fit before the barrel is unchucked.

There are these things called wires, and thread mikes.
While I concur it is preferable to have the device- I have no problem threading to a spec if that is requested.
High-quality devices will be within the tolerances needed and there shouldn't be an issue if I do my part- and they do theirs.

Prefit barrels are commonly sold nowadays- based on precise repeatability of thread clocking and headspace tolerances to some high-end receivers.

 

[KY_Windage]

There are these things called wires, and thread mikes.
While I concur it is preferable to have the device- I have no problem threading to a spec if that is requested.
High-quality devices will be within the tolerances needed and there shouldn't be an issue if I do my part- and they do theirs.

Prefit barrels are commonly sold nowadays- based on precise repeatability of thread clocking and headspace tolerances to some high-end receivers.

Oh, I know. But having seen a well-respected machinist/gunsmith get it wrong, and having had that be a real pain to get fixed, my advice is, have the device there for them to make sure it threads on, and without having to over-cut.

The machinist afterward swore he had cut the threads to the suppressor mfgr's specs. However, nothing we had, which was 3 QD connectors and one direct-thread, would go on. He had clearly screwed up, but it w/n/h happened if he had had the device to check it.

 

[KY_Windage]

This is absolutely incorrect.

Any gunsmith- 01 or 07, can possess/work on customers' NFA items- even without a SOT.
BATFE recommends a Form 5 be completed, but it is not required.

Here:

https://www.atf.gov/firearms/docs/repair-nfa-firearms/download

And here:

May a licensed gunsmith receive an NFA firearm for purposes of repair? | Bureau of Alcohol, Tobacco, Firearms and Explosives

Yes, a licensed gunsmith may receive a National Firearms Act (NFA) firearm for the sole purpose of repair and subsequent return to its owner. It is suggested that the owner obtain permission from ATF for the transfer by submitting an ATF Form 5, Application for Tax Exempt Transfer and...

www.atf.gov

That's great, but I don't trust the government to not say, "We said repair of the NFA item. We did not say to fit it to anon-NFA item."

 

[tobnpr]

That's great, but I don't trust the government to not say, "We said repair of the NFA item. We did not say to fit it to anon-NFA item."

Difference without a distinction.
I can fit a customer's suppressor to his barrel without needing a SOT.
Just had one want to send me his Form 1 can that was not fully assembled to fit- I told him as soon as I so much as screwed the end cap on it would no longer be a Form 1.

"Repair" is the same as service/firearm modification. It doesn't only apply to stuff that's "broke".
A rebarrel to a customer's receiver is considered "repair". Threading for a muzzle device is considered the same. This is why the can be shipped direct to the smith (or manufacturer) and directly back to the customer without an FFL intermediary.

An 01/01 SOT cannot assemble/manufacture suppressors- only sell/transfer.
An 07/02 SOT can manufacture and sell/transfer.

 

[escopeta]

Been doing this for over 10 years and only used spiders and indicate off the bore. For checking I use class 3 ring gauges which is industry standard and never had a customer issue. Also use thread specific cutting inserts.

 

[Fast14riot]

I hope OP got his barrel threaded in the last 4 years...

 

[Carl S]

You don't have to send it to the manufacturer.threading will not affect the crown unless you shorten the barrel.you don't need the suppressor to determine thread fit.screw ring gauges or thread mic will do it for you.any machinist can do it if he can set the barrel up and cut the thread's to spec square to the bore-including the shoulder.