I have a RRA 18" Varmint upper that I am considering modifying by replacing the aluminum tube forearm with a DD and also turning the barrel down to something less than .920" that it is now.

My question is if I turn the barrel down to something less than .920 the entire length but more than .750" as standard, can I get a gas block that is a size in between?

Thanks,

77Bronc

just dont turn it down at the gas block

How much added functionality are you going to get from a .85 barrel or .7934" versus the .920 you have, or more to my point, from just going to a straight .750?  I guess I don't understand why you'd go to the trouble of turning to an odd size and finding an odd FSB/gas block when you could just go to either:
1) a stepped barrel that's big in the back and .750 at the block and forward,
2) a straight .750,
3.) flutes in your .920

You're gonna spend a ton to get a custom-sized gas block in addition to the price to turn the barrel!  I'd suggest you just go to a straight barrel.

My $.02, and worth about that much, too.