I want to have my M&P 10 barrel threaded for a suppressor. It has no threads now just straight barrel to the muzzle.
What should that service normally cost?
It will be 1/2x28.
I found a place that will do it for $120 with a 7 week turn around.
I asked about taking the bevel off the shoulder of another barrel that is already threaded and was told the price would be the same even though they are not threading that one.
Is it really necessary to flatten that shoulder to square and true the suppressor to the muzzle?
New to suppressors here, thanks for any info.
Maybe this belongs in the Smithing sub forum.

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“Look life in its iron face”

Let me look what the correct thread size is. Typically, larger bore rifles use a different thread on the muzzle. BRB.

After a quick internet search, I confirmed the proper thread is 5/8 X 24.

Yes, it’s not only necessary, it’s imperative! The shoulder MUST be dead square with the threads. Will your gun “blow up” if it’s not? Likely not. Do you want it any other way? Absolutely not!

M29since14 is correct. You want the threads and shoulder true to the barrel to prevent baffle strikes.

Just keep in mind, even with a properly installed suppressor, there is going to be a shift in point of impact due to the nature of the muzzle device and if you take the suppressor off, it will shift again.

As far as prices and turn around time, I have no idea. If it was just a muzzle brake or a flash suppressor, I wouldn't have a problem threading the barrel myself (with the proper tools) but with a suppressor, it's better to let a gunsmith do the work.

You are correct on the thread pitch. I confused that with the 5.56

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“Look life in its iron face”

I had a barrel threaded to 5/8-24 last summer for $35 another shop locally is $60. (Stripped barrels, not on a lower.)

Ivan