Additional lead weight bars are available which can be slid behind the 3 and 9 o’clock Picatinny rail positions. These weights have knurled nuts pressed into them which correspond with screw holes on the MK7 NM handguard. The lead weights can be cut down by the rifleman and moved forward or backward along the weapon to achieve the balance they prefer. Mfg: Geissele Automatics Llc