Gas blocks should normally be about.030-.035" off the shoulder of the barrel.
In most cases, if both the barrel & the GB are done right, it you push the GB up tight against the barrel shoulder, you will not have optimum alignment,
But the GB port is a fair amount bigger than the barrel gas port to allow for some amount of misalignment...............like with many things, it a question of how much.
I always measure the center of the barrel port distance from the shoulder & the GB port center distance from the rear edge of the GB. Never don't work....................measure twice, cut once.
MM
