Suppressors .338 SR Ultra

Yes to the 338 Ultra SR, but I would avoid the 3/4x20 threads. Very rare threading so unless your rifle is currently threaded that way you should go 3/4x24 or 5/8x24.
 
I don't have the rifle. Bought a 50% off certificate in the classifieds and to maximize the discount I ordered the .338 SR Ultra. So I will need to build a .338 rifle in the future after my 280AI is done.