A maxed-out storage stock in earth tone, ready to bolt on — that’s the idea here. The ACS ships as a bare buttstock with no tube or hardware, so we’ve matched the genuine ACS in Flat Dark Earth (MAG370FDE) with a complete carbine buffer tube assembly and packaged them together. The FDE finish slots neatly into a tan or two-tone build.
ACS stands for Adaptable Carbine/Storage, and storage is the headline. Two rear-accessible, water-resistant battery tubes flank a separate covered compartment in the butt, giving you more onboard room than any other stock in Magpul’s carbine lineup — spare batteries for a light or optic, cleaning patches, and small tools all stay with the rifle.
The supplemental friction lock pulls the play out of the buffer-tube fit for a steadier cheek weld, and the streamlined, anti-snag shell keeps the release latch from catching on gear. A 0.30″ rubber butt-pad grips the shoulder even over a plate carrier, and the fixed cheek piece keeps your head position consistent shot to shot.
Filling out the recoil system is the buffer tube assembly: a 6-position mil-spec receiver extension, carbine buffer, recoil spring, castle nut, and end plate, all 1.148″ mil-spec. It fits any mil-spec AR-15/M16 lower, 80% lowers included. Add a lower parts kit, or browse other stocks and buffer tube kits.
Included in this combo:
- Magpul ACS (Adaptable Carbine/Storage) Carbine Mil-Spec Stock — Flat Dark Earth (MAG370FDE)
- Mil-spec carbine receiver extension (6-position buffer tube)
- Carbine buffer
- Action / recoil (buffer) spring
- Castle nut
- Receiver end plate
ACS stock specs:
- Drop-in replacement for AR-15/M16 carbines on mil-spec receiver extensions
- Two rear-accessible, water-resistant battery storage tubes
- Separate covered storage compartment in the butt
- Supplemental friction lock minimizes stock movement
- Streamlined, anti-snag profile shields the release latch
- Dual ambidextrous QD sling sockets
- Fixed cheek piece for a consistent cheek weld
- 0.30″ rubber butt-pad; six length-of-pull positions
- M4 length of pull: 11.6″ collapsed, 14.9″ extended; adjustment range 3.3″; max length 8″
- Weight: 14.1 oz; Made in the USA
WARNING (Prop 65): This product can expose you to chemicals known to the State of California to cause cancer and reproductive harm. For more information, see www.p65warnings.ca.gov.
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