Would someone please explain to me about the gas blocks or provide a link to a website somewhere that does? On their configurator, Robinson shows "L GB2" and "L GB3" for the standard exposed gas block XCR. They show "L GB3 Micro" for the Micro XCR. Then there's this one linked below for sale that doesn't even seem to be configurable on Robinson's website. How can that be?
The difference between an exposed gas block and one that's not is obvious. But what are these other differences?