Eric at Garand Gear has come up with an alternate to adjustable gas plugs. He calls it a ported gas plug. The difference is that instead of venting a portion of the gas, his ported plug is hollow, adding volume to the gas expansion chamber. More volume = less pressure.
M1 Garand

His idea makes sense to me so I ordered one and it arrived a couple days ago. I have not had the time, yet, to try it out.