If you turn off the gas system does it hurt anything? Is it hard on the bolt lugs? Anything else? I know it'll be a single shot but that is not my concern.

There is no need to turn off the gas - how heavy a bullet are you shooting and at what velocity? (load?)

There are a number of cures if you are going to go down that road:

1) Port the gas plug (usually a .036 - .040 will do it)
2) Have a slot cut in the top of the gas piston - .025 x .030-.050 deep
3) Tune the gas plug length to maximize dwell time in the gas system (also improves accuracy)

1SGA

Not actually planning on it but if I have to ever use whatever is available at the time I was just curious. I know on the Garand you have to be careful with especially some of the hunting loads of today. [yes I know you can buy a "fix" for it]

Just wondering if shutting off the port would cause problems in the future.