Are you following the AR-15 upper receiver “how to” series? In this post, I will be covering the gas block and gas tube installation with the ones that I chose to purchase for my AR-15. There are a tremendous amount of different low profile gas blocks available on the market today, but these two appear to be the most popular: clamp on style and set screw style. I built my AR-15 upper receiver with a clamp on style gas block. Let’s get started.
Before you install the gas block, the first thing you will want to do is install the gas tube into the block itself. This is done by inserting the gas tube into the gas block and driving a small roll pin into place, which ensures that the gas tube isn’t easily removed. To make these steps a little easier, you may want to check out the Geissele Gas Block Roll Pin Tool and Gas Block Pin Punch Set. I will be covering these specific tools in a later article.
After the gas tube is installed properly, slide the gas block over the barrel. Be sure to check the gas tube alignment into the upper receiver and for proper alignment with the gas port in the barrel. I typically slide my bolt carrier into the upper receiver to make sure that the gas tube does not bind or snag on the gas key. It should fit without friction.
To help with aligning the gas block to the gas port on the barrel, I marked a pencil line down the center of my gas block, and down the center of the barrel. Then I lined up both marks and tightened down the screws on the gas block with some thread lock.