How to Build an AR-15 Upper Receiver – Forward Assist

Last week, we started our AR-15 upper build with laying out the tools we’ll be using. It is now time to start pounding some stuff and getting things installed into your AR-15 upper receiver. Specifically, I will be covering how to install the forward assist into a stripped upper receiver. Remember that not all AR-15 upper receivers have forward assists, so if yours does not have one, you can skip this step. Also, keep in mind that I, and The Arms Guide overall, assume no responsibility for any laws or regulations you may violate or any injuries you may cause. You are responsible for your safety and for following your local laws. All right, let’s get that forward assist installed.

Items Needed

To install the forward assist into your AR-15 upper receiver, you will need the following items (which I went over in last week’s article):

– Forward assist

– Forward assist spring

– Forward assist roll pin

– Upper receiver vise block

– Roll pin starter

– Roll pin punches (3/32″)

– Brass or synthetic hammer

Installation Process

Installing the forward assist is a quick and easy process.

Sliding the forward assist spring over the forward assist will be the first thing you do. Without this spring installed, you will have no spring tension and you will have to re-install the forward assist, so make sure to place the spring correctly before anything else. Now with your AR-15 upper receiver in a vise block, or at least secured in place by something that will not damage your upper receiver, slide the forward assist into position with the “tooth” curving inward.

Once you have the forward assist in position, push a roll pin punch through the hole on the under side of the upper receiver and capture the forward assist in place. This will assist with keeping everything lined up when you move on to the next step.

Grab the forward assist roll pin and a roll pin starter and begin tapping the roll pin into place with the hammer from the top of the receiver. It is important to check the forward assist for proper function by pushing it during this process. This will make sure you are not binding or catching the roll pin on anything. Use the roll pin starter and your small hammer to drive the roll pin into the upper receiver enough to hold the forward assist in place and then utilize the 3/32″ roll pin punch to finish driving the roll pin into place. Once finished, the roll pin should be flush with the top of the upper receiver.

Perform a function check and make sure there is no binding of the forward assist. The forward assist should push in smoothly and the spring pressure should allow it to release back out easily. If the forward assist works as it should then you are ready to move onto the next step: installing the ejection port cover, which will be the subject of next week’s article. Be sure to check back then for the next installment.