YHM DUST COVER ASSY 300 BLK

Description

Running two uppers on the same lower — one in .300 AAC Blackout and one in 5.56 — creates a genuine risk of feeding the wrong cartridge, since both use the same magazine and the same bolt carrier group. A .300 Blackout round will chamber in a 5.56 upper and the result is destructive. The practical answer is to mark the upper in a way that is visible before you ever press the bolt release, and that is exactly what this Yankee Hill Machine dust cover is designed to do.

The caliber marking sits on the exterior face of the cover, readable at a glance when the port is closed. Flip it open and you are working with a plain cover — the marking is not on the interior, so it does not interfere with the ejection port or obstruct anything mechanically. Installation follows standard AR dust cover procedure: the assembly ships with the rod and retaining clip spring already included, so you are not hunting for hardware that should have come in the box.

The cover is a drop-in replacement for any mil-spec AR-15 upper receiver and requires no modification to the receiver itself. For anyone running a dedicated .300 Blackout upper, this is a low-cost, permanent identification method that survives range trips and storage in a way that tape or paint markers simply do not. If you also want to remark an upper receiver that was previously marked for a different caliber, the dust cover solves that cleanly without touching the receiver itself.