If you are using the longer, heavier bullets in your AR-15, then you need a Sinclair AR-15 Single Shot Follower. The longer, heavier bullets are normally loaded longer than magazine length. The Sinclair AR-15 Single Shot Follower positions the 223 Remington cartridge loaded with longer bullets correctly for smooth feeding into the chamber. Once a round is fired, the bolt retracts and locks behind the follower in the empty/loading position. No need to take your magazine apart! It takes only a few seconds to install the Sinclair Follower on top of the existing follower. It can be removed just as quickly. This follower addresses many of the problems with existing single shot followers on the market. The satin finished anodized aluminum wears better than the plastic followers and is easily noticeable in the magazine. Works perfectly in GI metal magazines and Brownell magazines. Will not work in any of the inexpensive, plastic magazines we tested.
AR-15, Issue:09, Page:056
Sinclair, Issue:3B, Page:221