A suppressor needs a decent shoulder to stop against because that's what aligns it to the bore. Relying on a tight thread alone for alignment is not enough, especially if/when fouling builds up in the threads (mostly an issue when swapping between different thread lengths). A locknut is OK for a brake, not good enough for a suppressor IMO.
On a sporter weight 30 cal barrel I personally always choose and recommend 9/16"-24 rather than 1/2"-28 if possible. A larger thread is almost always better when it can be done right.
If a guy is having special adapters or collars made, you can have an adapter made to shoulder on the muzzle instead of a barrel shoulder; this lets you go with a larger thread size. I've done more than a couple barrels this way myself and machined adapters to match.
Can you post examples of your work? Thx, R
Judges 21:25 “Everyone did what was right in his own eyes.”
Liberal=liberated from God...How's that working out?