Machinist question.

[slap shot]

UPDATE: There were no threads on the muzzle to begin with.

I’m thinking about threading an .22 AR barrel in 1/2 28 to mount a suppressor. I was just going to use an adapter to go from 5/8 24 but the origin Chiappa barrel had a pressed on flash hider. It's smooth and .500 OD. I would just buy a threaded but i'm not sure if a standard AR profile rimfire barrel is a drop in.
Thanks

this is edited for clarity

 

[Rob Boudrie]

A machinist would probably cut those threads on a lathe. I do not see good things happening if an inexperienced, or even an experiences, tries to thread a barrel with a tap and die. I would never take one of my guns to a smith who used that approach.

 

[slap shot]

A machinist would probably cut those threads on a lathe. I do not see good things happening if an inexperienced, or even an experiences, tries to thread a barrel with a tap and die. I would never take one of my guns to a smith who used that approach.

I was afraid if that. The only reason I was asking is that its an el cheapo chiappa upper and I’m only concerned about the can.

 

[Rob Boudrie]

The danger is not only to the threads of the can, but a slight lack of concentricity could result in the bullet hitting the baffles.

 

[slap shot]

The danger is not only to the threads of the can, but a slight lack of concentricity could result in the bullet hitting the baffles.

that's what I meant. I don’t wanna shoot myself in the can! Lol

 

[JDL]

There is special set of die tools with a centering pilot. this system will work without a problem if you take your time, have the skill set, and use cutting oil. You my also have to recrown the barrel . There are hand tools available to do the recrown. Of course the time you spend and money you will spend for the tools and the possibility of screwing this up. You may want to consider having a gunsmith do this job. The tools are available from Brownells. A good smith can uses these tools with perfect results.

 

[Sweeney]

If you want to cut new threads at 1/2-28, down from 5/8-24 you would first need to turn the barrel down to 1/2". You can't just just use a die. I think you can buy kits for this but it would be better to bring it somewhere to have it done on a lathe...turn the barrel down and single point cut the threads. Properly done, the barrel would be centered relative to the bore and not the OD of the barrel.

 

[50wt]

Everything has to , or should run true to the boreline. Sstup in a chuck and indicated in.Thats the right way. Then you could make any size thread adapter .

If the exit hole is large enough, say a .30 cal can on a .22 , the can could run out a bit but still have enough clearance for rhe exiting bullet.

Even with marred threads, there may be enough to hold the can.

Can you take a photo?

 

[teamRR]

I would probably just buy a new barrel, is there some reason you can't?

 

[Dave Marshall]

I would probably just buy a new barrel, is there some reason you can't?

A new rimfire barrel, properly threaded, is probably your best way out.

 

[slap shot]

I would probably just buy a new barrel, is there some reason you can't?

no, that’s probably the smart move.

 

[slap shot]

Everything has to , or should run true to the boreline. Sstup in a chuck and indicated in.Thats the right way. Then you could make any size thread adapter .

If the exit hole is large enough, say a .30 cal can on a .22 , the can could run out a bit but still have enough clearance for rhe exiting bullet.

Even with marred threads, there may be enough to hold the can.

Can you take a photo?

 

[50wt]

Yep. you done ruined that barrel.

 

[slap shot]

Yep. you done ruined that barrel.

i thought so but it turns out it was never threaded to begin with! I just remembered that the original A2 was held on with a set screw. What appear to be threads now is from me removing the brake i installed a few years ago. I just spot welded it in place.

New barrel needed regardless but i feel a little better, loss of memory not withstanding.


View: https://www.youtube.com/watch?v=rlcruI9NdrE

 

[50wt]

So it was a slip fit? Even better

 

[one-eyed Jack]

All of the above. Get it done right. Forget the name, but I've gotten adaptors 5/8-24 (can) to various barrel threads, 1/2-28, 1/2-36, etc. from them. Jack.

 

[pupchow]

This guy turns down a lot of barrels Class 3 Machining

 

[BobR51]

Machinist here, 28 yrs. experience.
Do you have a micrometer?
Just for shiits, measure the diameter of the messed up threads.
My guess is you removed the muzzle break that was pinned and it had some pin still inside and messed up the thread on removal.
If there's diameter there larger than .505- .510. It may be possible to run a die over it.
Also, does the barrel have anything protruding from it that would make it hard to chuck in a lathe?
I would just have a qualified machinist look at it and get their take on it.

 

[vcman]

You need a lathe, at minimum a good big drill press, it take a bit of money to do a setup like that. It cheaper for ya to buy a newbarrel.

 

[slap shot]

Machinist here, 28 yrs. experience.
Do you have a micrometer?
Just for shiits, measure the diameter of the messed up threads.
My guess is you removed the muzzle break that was pinned and it had some pin still inside and messed up the thread on removal.
If there's diameter there larger than .505- .510. It may be possible to run a die over it.
Also, does the barrel have anything protruding from it that would make it hard to chuck in a lathe?
I would just have a qualified machinist look at it and get their take on it.

i do have a micrometer but there were never threads. i'll measure it next time i'm in the garage.

i need to update the original post. I miss my dad having a lathe and bridgeport in the garage, but no more now that he's in FL

 

[teamRR]

Ya so new barrel is the simple thing, but just in general I would never bother unpinning a barrel - you always run the risk of destroying it and it seems better to keep a good working spare than to spend time and $$ potentially destroying what is typically < $250 to replace with new parts.

 

[drgrant]

Ya so new barrel is the simple thing, but just in general I would never bother unpinning a barrel - you always run the risk of destroying it and it seems better to keep a good working spare than to spend time and $$ potentially destroying what is typically < $250 to replace with new parts.

You can unpin a barrel just fine and any smith/machinist worth their salt can do it and put on a new device etc.

The key here is to stop flinting and let an expert do it. Most of them will do this kind of work for
relatively short money.

-Mike

 

[slap shot]

You can unpin a barrel just fine and any smith/machinist worth their salt can do it and put on a new device etc.

The key here is to stop flinting and let an expert do it. Most of them will do this kind of work for
relatively short money.

-Mike

no, the key is to remember that the device isn't threaded on, especially if you're the guy that installed it

 

[BobR51]

1/2-28 External Thread:
Major Diameter Max = 0.5000, Min = 0.4935

When I re-thread something like that I generally chuck the part in the lathe. (Careful not to crush or mar it up).
Put the speed in a lower speed setting to lock it so it doesn't turn by hand.( the lathe doesn't even need to be powered up for this)
Set up an adjustable 1/2-28 die in a handle. It the bed gets in the way of turning it you can use a large adjustable wrench.
I bring the tail stop with a drill chuck mounted against the die to start it straight.
Plenty of cutting oil and turn slowly while turning the drill chuck in to keep pressure on the die.
Once you're on there and started, you can back off every half turn to break the chip.

***BTW, this is just some info for you. This is not simply re-threading a shaft for a spanner nut.
You are after all fixing something that is at the end of a "controlled explosion".***

 

[Sweeney]

^ This is not a re-threading job. This is turning down the barrel and cutting new 1/2-28 threads.

 

[slap shot]

^ This is not a re-threading job. This is turning down the barrel and cutting new 1/2-28 threads.

Understood. Wasn’t sure how to ask what I thought I needed but you describe it correctly.

 

[JDL]

At this point just Get a new replacement barrel or file this one to a point and hammer a brake on

 

[slap shot]

At this point just Get a new replacement barrel or file this one to a point and hammer a brake on

the barrel is as it was originally. Had to be replaced or threaded to put a can on.

 

[slap shot]

I measured the muzzle and it’s exactly .500

also, I pulled the barrel and I’m wondering if this isn’t a propriety setup. No experience with AR platform .22 barrels. I’d prefer to replace with new but figured I’d ask here if this is a standard swap out. Here’s a couple of pics of the chamber end.

 

[slap shot]

1/2-28 External Thread:
Major Diameter Max = 0.5000, Min = 0.4935

When I re-thread something like that I generally chuck the part in the lathe. (Careful not to crush or mar it up).
Put the speed in a lower speed setting to lock it so it doesn't turn by hand.( the lathe doesn't even need to be powered up for this)
Set up an adjustable 1/2-28 die in a handle. It the bed gets in the way of turning it you can use a large adjustable wrench.
I bring the tail stop with a drill chuck mounted against the die to start it straight.
Plenty of cutting oil and turn slowly while turning the drill chuck in to keep pressure on the die.
Once you're on there and started, you can back off every half turn to break the chip.

***BTW, this is just some info for you. This is not simply re-threading a shaft for a spanner nut.
You are after all fixing something that is at the end of a "controlled explosion".***

since it’s .500 maybe just easier to hand off to a gunsmith for threading.