CMMG MK4 .300BLK Banshee Upper Group Receiver 8in 1-7 Twist 5/8 X 24 TPI 16.5in Armor Black
All CMMG upper receivers
Click to see full view
CMMG
Overview
The CMMG Mk4 .300BLK Banshee Upper Group Receiver features a complete assembly designed specifically for the AR-15 platform. With an 8-inch barrel and a 1:7 twist rate, this upper is optimized for the .300 Blackout caliber, allowing for effective stabilization of heavier projectiles, making it suitable for both supersonic and subsonic ammunition. Commonly found in builds focused on .300 Blackout, this upper receiver is an excellent choice for those looking to maximize versatility and performance in a compact format.
Specifications
CMMG MK4 .300BLK Banshee Upper Group Receiver 8in 1-7 Twist 5/8 X 24 TPI 16.5in Armor Black
October 2026 on GunPartPicker
CMMG MK4 .300BLK Banshee Upper Group Receiver 8in 1-7 Twist 5/8 X 24 TPI 16.5in Armor Black ranked #360 of the 844 upper receivers builders added on GunPartPicker in October 2026. Builders have added it to their builds on GunPartPicker. Since April 2026, it ranks #134 of the 2,064 upper receivers builders have added. Builds with this upper receiver are nearly all chambered in 300 Blackout, nearly all on carbine-length gas, and nearly all AR-15.
It was hard to find in October 2026, in stock on only 5 of the 12 days we checked, and today only Optics Planet has it in stock. Prices barely moved in October 2026, holding around $789.99, with no real sale all month. Buying today, the lowest price is $839.99 at Optics Planet, above October's low of $789.99, so a better deal may come back.
Updated · from real builds on GunPartPicker · Prices checked · refreshed daily across 37 retailers
Not sure which upper receiver to pick?
We ranked every upper receiver by how often it shows up in real builds on GunPartPicker.
Read the guide: Most Popular AR-15 Upper Receivers →Check it against the live catalog:
Frequently Built With
The part most often added in each category by the builds that include this one
PSA PA15 MOE Complete Lower w/ SBA5 Brace, Black
Aero Precision AR-15 Breach Charging Handle Ambidextrous Small Levers
Magpul AFG-2 Angled Fore Grip - Black
Holosun ARO Red Dot Sight Gold 2 MOA Dot with Picatinny Mount Matte Black
Geissele Automatics AR-15 SSA-E X Lightning Bow Trigger
Wilson Combat AR-15 Starburst Gunfighter Pistol Grip Black
No reviews yet. Be the first to review this product!