Chattahoochee Munitions manufactures the CM15 20-inch 6.5 Grendel AR15 rifle, a complete factory AR15-pattern semi-automatic with a straight-fluted 416R stainless barrel, a 1:8 twist, and a rifle-length gas system. This Cobalt Kinetics Green Cerakote configuration weighs 7 lb 4 oz with an unloaded magazine.
See every Chattahoochee Munitions 6.5 Grendel rifle, upper, and magazine at Grendel’s Lair, and read the 6.5 Grendel guide for the cartridge background.
A Long-Range 6.5 Grendel AR15 Rifle
This 6.5 Grendel AR15 rifle uses the longest CM15 barrel to get the most from the cartridge’s efficient 6.5mm bullets, giving the flattest practical trajectory in the CM15 lineup. The rifle-length gas system, adjustable gas block, and Odin adjustable buffer keep cycling smooth, and the 15-inch free-float handguard leaves room for a bipod and accessories.
Weighing it against other cartridges? Read 6.5 Grendel vs 6mm ARC and 6.5 Grendel vs 6.8 SPC. The 6.5 Grendel barrel length comparison shows what the 20-inch barrel adds over the 16- and 18-inch rifles.
Barrel and Gas System
The 20-inch 416R stainless steel barrel is straight-fluted, finished in E100 Blackout Cerakote, and cut with a 1:8 twist that stabilizes the common range of 6.5 Grendel bullets. It runs a rifle-length gas system with a .750-inch gas journal, a Melonite gas tube, and a Superlative Arms adjustable gas block. A shouldered crown and 5/8×24 threads accept a muzzle device or suppressor. Because the CM15 is gas operated, Chattahoochee Munitions recommends a flow-through suppressor to limit back pressure, and the adjustable gas block and Odin adjustable buffer help tune the rifle for suppressed use.
Receivers, Bolt, and Trigger
CNC-machined 7075-T6 billet receivers carry an integral trigger guard, a flared magazine well, and ambidextrous safety, magazine release, and bolt release. The CM15 Low Mass bolt carrier group uses a 9310 steel bolt manufactured to the Grendel Type II specification, with nitride-coated bolt, carrier, and gas key. Fire control is a TriggerTech AR15 Duty trigger in single-stage straight, single-stage curved, or two-stage straight, each at 3.5 lb total pull.
Cobalt Kinetics Green Cerakote Finish
This 6.5 Grendel AR15 Rifle is finished in Cobalt Kinetics Green Cerakote on the upper and lower receivers, buffer tube, and handguard, with a Coyote B5 Systems Bravo stock, grip, and rail covers. Every CM15 20-inch 6.5 Grendel shares the same mechanical specifications; only the finish differs. One 10-round 6.5 Grendel AR15 magazine is included.
CM15 20-Inch 6.5 Grendel Specifications
- Manufacturer: Chattahoochee Munitions
- Platform: CM15 AR15-pattern semi-automatic rifle
- Chambering: 6.5 Grendel
- Barrel: 20-inch 416R stainless steel, straight-fluted, E100 Blackout Cerakote
- Twist rate: 1:8
- Muzzle: 5/8×24 threads, shouldered crown
- Gas system: Rifle-length, .750-inch gas journal, Melonite gas tube
- Gas block: Superlative Arms adjustable
- Buffer: Odin adjustable AR15 buffer, CM mil-spec buffer tube, QD endplate
- Bolt carrier group: CM15 Low Mass BCG; 9310 steel bolt manufactured to the Grendel Type II specification, HPT/MPI tested; nitride bolt, carrier, and gas key; tool-steel extractor
- Receivers: CNC-machined 7075-T6 billet upper and lower, integral trigger guard, flared magazine well
- Controls: Ambidextrous safety, magazine release, and bolt release
- Charging handle: CM15 ambidextrous 7075 charging handle, made in collaboration with Breek Arms
- Trigger: TriggerTech AR15 Duty: single-stage straight, single-stage curved, or two-stage straight; 3.5 lb total pull
- Handguard: 15-inch CM15 LWS M-LOK, dual-taper attachment with steel barrel nut, M-LOK sides and bottom, full-length top Picatinny rail, QD sockets at 3 and 9 o’clock
- Stock and grip: B5 Systems Bravo stock, B5 grip and rail covers
- Finish: Cobalt Kinetics Green Cerakote on the upper and lower receivers, buffer tube, and handguard, with a Coyote B5 Systems stock, grip, and rail covers
- Magazine: One 10-round DURAMAG 6.5 Grendel AR15-pattern magazine
- Weight: 7 lb 4 oz with unloaded magazine, no accessories (listing weight is for shipping)
- Overall length: 37.50–40.75 inches
- Length of pull: 11.00–14.25 inches
Frequently Asked Questions
Who makes a 6.5 Grendel AR15 rifle with a 20-inch barrel?
Chattahoochee Munitions manufactures the CM15 20-inch 6.5 Grendel AR15 rifle with a 1:8 twist 416R stainless barrel, rifle-length gas system, adjustable gas block, and TriggerTech AR15 Duty trigger.
Who manufactures the Cobalt Kinetics Green Cerakote CM15?
Chattahoochee Munitions designs and manufactures the CM15 6.5 Grendel. Cobalt Kinetics Green is the name of the Cerakote finish color applied to the receivers, buffer tube, and handguard of this rifle; it identifies the finish, not the manufacturer.
What twist rate does the CM15 20-inch 6.5 Grendel use?
A 1:8 twist, which stabilizes the common range of 6.5 Grendel bullets from lighter predator loads to heavier hunting bullets.
What gas system does it use?
A rifle-length gas system with a .750-inch gas journal and a Superlative Arms adjustable gas block.
What magazine does the CM15 6.5 Grendel use?
A 6.5 Grendel AR15-pattern magazine. One 10-round 6.5 Grendel AR15 magazine is included. CM15 and CM7S magazines are not interchangeable.
What suppressor does Chattahoochee Munitions recommend for the CM15?
A flow-through suppressor. The CM15 is gas operated, and a flow-through design limits back pressure so the rifle is easier to tune. Confirm the suppressor is rated for 6.5 Grendel and the barrel length.
What bolt does it use?
A CM15 Low Mass bolt carrier group with a bolt manufactured to the Grendel Type II specification. It is not interchangeable with the CM7S bolt-action bolt.
Does the finish change performance?
No. All CM15 20-inch 6.5 Grendel rifles share the same mechanical specifications; Black Tungsten Cerakote, Cobalt Kinetics Green Cerakote, and FDE Metallic Cerakote differ only in color.
How much does it weigh?
7 lb 4 oz with an unloaded magazine and no accessories. Any heavier listing weight is the shipping weight.
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