Adapting an MIA for a suppressor

by Miles , CIVITATES AMERICAE, Thursday, November 02, 2017, 23:52 (2579 days ago) @ Tom Richardson

is an exercise in frustration control.

Delta P Design and Smith Enterprises are the only two manufacturers that make serviceable adapters to keep the front sight at the muzzle and provide a standard 5/8 X 24 thread. Delta P is Titanium while Smith's is Steel, but either will do the job.
Grizzly Gunworks makes a thread adapter, but you lose the front sight (no big deal if you're going scoped).

However!

The thread pitch on the barrel for the castle nut is 595 X 32 NS and the main problem is that Uncle never had a specification for absolute concentricity of the thread with the bore. Civilian Springfield Armory and other MIA manufacturers never seemed to care either.

You are at the mercy of the unknown machinist who threaded the barrel and what you have is what you get. If the threading is 'off', the adapter and thus the suppressor will not be aligned with the bore and you'll be tempting, at best, a baffle strike and at worst a blown can. And there is nothing that can be done short of cutting the barrel back having the threads cut on a lathe.