I think, and I could be wrong, that the conversion kits are all the new gas system.
If you are changing calibers, the gas system comes out with the barrel, so in my thinking, couldn't you have a barrel with the old system and another with the new system and it wouldn't make any difference?
If you are changing calibers, the gas system comes out with the barrel, so in my thinking, couldn't you have a barrel with the old system and another with the new system and it wouldn't make any difference?