Suppressing the PTR91 - what surface to time to

[sucker76]

I have a PTR91 and went to add my QD flash hider for my older Saker suppressor and under the factory flash hider was a collar machined in the barrel between the threads and shoulder. The factory flash hider was machined to fit over it and i think it seated on this and not the shoulder. The Saker flash hider seems to stop on the muzzle and not the collar and not the shoulder. The new flash hider was a little wobbly over this collar until it was cinched down. Is the muzzle going to be OK for a seating surface and still have concentricity? This seems like a large gap for shim washers but I really don't know. I didn't measure the diameter of the machined collar but it is less than the shoulder.
Any advice is welcome.

I do have a direct thread adapter for the can but have to go searching for it so for now I am concentrating on getting the QD working.

 

[DustyDuds]

As long as the flash hider allows .020 total clearance (.010 per side) u should be fine.

 

[sucker76]

I don't quite follow what you mean. My question was about justifying on the shoulder of the barrel or the muzzle.