NSN s for M249 SAW and M240B and other variants
NSN 1095-01-599-4868 36" x 15" x 84" cabinet holds 12 M249s or 6 M240s and 6 M249s. Stored spare barrel with weapon.
NSN: 1095-01-599-4865 36" x 15" x 84" Crew served weapon rack holds 6 M240s or 6 M249s with 900lb capacity storage shelves above.
also hold M2s and MK19s
More info:
http://www.secureittactical.com/military/nsn/NSN-weapon-racks.html