I put one of the Schuster adj gas plugs in my M1 and it works great. The main reason I wanted it was to be able to reduce the recoil energy of the op-rod, slow things down so to speak.
You can adjust it, simply done w/an allen wrench so the ejected cases fall a mere couple of feet out at 2 & 3 o'clock.
Op-rods are expensive, chasing brass is no fun. Not all 'milsurp' and nothing much packaged commercial 30-06 is loaded especially for Garands. This way you can use most anything w/o damaging the rifle plus have the brass in a small area for you when done shooting.
Someday I'll reload for it,,maybe.
I'm still shooting up WW2 corrosive primed stuff and some Korean mfg 30-06. Some of the K is corrosive,,some not.
The M1 gets cleaned as if it all is anyway. It's apart right now on the bench from Thursday shoot and cleaning yet.