MM BK2S Buttstock Extension

The BK2S's PDW buttstock is short by design, which is great for compactness but leaves too little room for a standard buffer-tube battery — the same battery format used in the BK1S. The MM BK2S Buttstock Extension solves that by lengthening the buttstock just enough to fit that standard buffer tube battery, without swapping the whole stock out.

It's a simple add-on piece rather than a full replacement part, so installation is a matter of fitting the extension onto your existing BK2S PDW buttstock rather than rebuilding your furniture from scratch. Offered in black, yellow, or silver to match the rest of your BK1S/BK2S build, it's the fix if you've been stuck using a smaller battery than you'd like purely because of stock length.