I'm planning out my first build and I am planning on going with a Green Mountain 18" barrel with rifle length gas. How expensive is it to get a sight pinned or am I better off going with a clamp on style?
I have used the Armalite clamp-on A2 sight base and it works well if you need a front sight. I have also successfully used several types of low profile clamp-on gas blocks.
I think it mostly depndw on what you plan on doing with the rifle and how rough you'll be on it. If your mostly going to be plinking or shooting from a bench, a clamped on gas block will mostly likely be fine. If you plan to use it to kick ass and take names, a clamped on gas block will still probably be fine but a pinned on one will be more durable. I tend to be a bit rough on stuff and if it can break, it will with me so I opt for the pinned on option but YMMV. If you do opt for the bolt on option, I would add some sort of reinforcement such as drilling dimples into the barrel where the fasteners attach to ensure that it doesn't turn into a single shot. Also, running the forearm over the top of the gas block adds a degree of protection to the gas block getting knocked out of allignment.