Lewis Machine (LMT)
If you are looking for early SOPMOD / SOCOM clone-correct builds, like the Mk18, the Gen1 B5 stock is what you need. This is the stock that was used by the US Military.
Gen1 stock does not have the QD sling connector, so slings were attached through the slats in the back and tied on. Later, B5 introduced a Gen2 stock which had QD connectors.
Hard to find, clone correct.
Available in Black and Coyote