Colt Front A2 Sight Gas Block Assembly w/ Gas Tube

Factory Colt front A2 sight base gas block assembly with gas tube for carbine length rifles.

Gas blocks and barrels must be drilled together. Drilling both the barrel and gas block at the same time ensures the gas ports align correctly.

Attempting to install a pre-drilled gas block on a barrel (or vice versa) can make proper alignment extremely difficult—and in some cases impossible. When Colt builds a firearm, the barrel and gas block are drilled together as a matched set for this reason.

We strongly recommend professional installation by a qualified gunsmith familiar with this process. Improper alignment can result in cycling issues or failure to function.