Does the CMMG Resolute MK4 6mm ARC Upper work with the Aero Precision 5.56 BCG W/C158 Bolt?
Upper Receiver
CMMG Resolute MK4 6mm ARC Upper
from $682.74
Bolt Carrier Group
Aero Precision 5.56 BCG W/C158 Bolt
from $148.99
CMMG upper and Aero Precision bolt carrier group compatibility
They fit, with a catch
The CMMG Resolute MK4 6mm ARC Upper works with the Aero Precision 5.56 BCG W/C158 Bolt, with one thing to check: Bolt Carrier Group (5.56 NATO) has a 5.56 / .223 bolt; a 6mm ARC build needs a 6.5 Grendel / 6mm ARC bolt.
No one has built this exact setup yet, but CMMG uppers with Aero Precision bolt carrier groups are a common pairing.
Counted from real GunPartPicker builds: parts lists people put together while planning to buy.
Checked by the same rules the AR builder runs on every part you add: caliber, frame size, receiver pattern, thread pitch and gas length.
Fit is judged from the specs retailers list, which can be missing or wrong. Confirm with the manufacturer before you buy, and have a qualified gunsmith check any build before you fire it.
How often builders pair the CMMG upper and Aero Precision bolt carrier group
Backed by thousands of qualified builds that have both an upper and a bolt carrier group.
Share of builds with the CMMG Resolute MK4 6mm ARC Upper and any bolt carrier group
- CMMG 5.5633%
Share of builds with the Aero Precision 5.56 BCG W/C158 Bolt and any upper
CMMG Resolute MK4 6mm ARC Upper
- Of upper picks
- 0.1%
- Median paid
- $680
Aero Precision 5.56 BCG W/C158 Bolt
- Of bolt carrier group picks
- 8.4%
- Median paid
- $132
How we count ⌄
These shares come from GunPartPicker's build data: real parts lists people put together while planning a purchase, not sales or surveys. A build counts a part only when it is the final pick for its slot, so parts that were swapped out never count. Fit never comes from these numbers; it comes from our compatibility rules alone.
Frequently built with the CMMG upper and Aero Precision bolt carrier group
The part builders pick most often in each slot alongside these two, checked against both. Parts that conflict are left out.
Charging Handle
Aero Precision Breach Small Levers
Fits both
Lower Receiver
Unconfirmed
Gas Block
Stock & Brace
Pistol Grip
Barrel
CMMG Resolute MK4 6mm ARC vs Aero Precision 5.56 BCG W/C158: specs and prices
| CMMG Resolute MK4 6mm ARC | Aero Precision 5.56 BCG | |
|---|---|---|
| Best price | $759.00 at GritR Sports | $148.99 at KY Gun Company |
| Stores | 3 of 5 in stock | 0 of 6 in stock |
| Assembly | Complete | n/a |
| Platform | AR-15 | n/a |
| Caliber | 6mm ARC | n/a |
| Length | 16.1 | n/a |
| Cartridge | n/a | 5.56 NATO |
| Finish | n/a | Black |
Both for $907.99 at today's best prices.
Today's best prices and 90 day price history
Every store we track for each part, cheapest in stock first. Prices are checked through the day.
CMMG Resolute MK4 6mm ARC Upper
Price history, last 90 days
- CMMG Resolute MK4 6mm ARC Upper: lowest $682.74 on Jul 5, highest $949.95 on Sep 24 over the last 90 days.
- Aero Precision 5.56 BCG W/C158 Bolt: lowest $131.53 on Jul 6, highest $149.99 on Jul 12 over the last 90 days.
Bolt Carrier Groups most paired with CMMG uppers
The CMMG Resolute MK4 6mm ARC Upper is not in enough builds yet, so these are the most picked next to any CMMG upper. Only parts our rules say fit the CMMG Resolute MK4 6mm ARC Upper are listed.
Bravo Company
Fits, check noteCheck fit
Wilson Combat Bolt Carrier Assy 5.56 NATO Polished
Fits, check noteCheck fit
Spike's Tactical 5.56 NATO Cut Lightweight
Fits, check noteCheck fit
Cryptic Coatings 5.56 NATO
Fits, check noteCheck fit
FAXON Chameleon 5.56 Nitride
Fits, check noteCheck fit
Upper Receivers frequently paired with the Aero Precision 5.56 BCG W/C158 Bolt
Most picked next to it in real builds. Only parts our rules say fit the Aero Precision 5.56 BCG W/C158 Bolt are listed.
