AR15 Single Shot Magazine with lockback

thingiverse

This is a single shot AR 15 Magazine that will allow you to load the AR one round at a time. This is good for testing rounds that normally would not fit in a magazine or you want to take out variability while testing a new load. Insert the magazine in the magwell like a normal magazine. Pull the bolt back and let it lock back. Place the bullet on the trough and slide it into the chamber or you can let the bolt just slam forward and insert the round. Fire and the round will be ejected and the bolt will lock back. Print the main body with 25% and the lock and bar with 100% infill. Clean up the bar and lock so they slide easily. To assemble you will need a spring with a 3.5mm OD. Put the spring in the pocket and test fit the lock. The lock should be flush with the top of rib. Trim the spring as needed. Make sure you have lots of tension on the lock. Then insert the bar through the hole. -----------------------***UPDATE***------------------------------- The single spring was sometimes not enough to lock it back, so I added a dual spring setup. You will need the dual spring body and dual spring lock. I also added a 5" long body, again dual spring setup, for competitions that require a 20 round mag look-a-like (see comments from aboxman).