+1-800-504-5897 Help Center Check Order Status
About Us Policies Reviews How To
Free Shipping & Free Returns*

FREE SHIPPING on Over 250,000 Products

Shop now and get Free Value Shipping on most orders over $49 to the contiguous 48 states, DC, and to all U.S. Military APO/FPO/DPO addresses.

Enjoy our FREE RETURNS

We want to ensure that making a return is as easy and hassle-free as possible! If for any reason you are not satisfied with your purchase, simply return the item within 30 days of receipt, and we'll cover the cost of return shipping. Learn more about our Return Policy.

  • Entire Store
  • ...
  • Apparel & Footwear
  • Astronomy
  • Everything Else
  • Eyewear
  • Hunting Gear
  • Lab Equipment
  • Military Gear
  • Outdoor Gear
  • Photography Equipment
  • Police, EMS & Fire
  • Shooting
  • Sport Optics
  • Sports & Hobbies
TIP
Shopping Cart

CMMG Upper Group Resolute Mk4 5.56x45mm 14.5in P&W Upper Receiver 55B360B-AB Caliber: 5.56x45mm NATO, Overall Length: 23.8 in, 15% Off w/ Free Shipping

Cmmg Upper Group Resolute Mk4 5.56x45 14.5'' P&w No Bcg Or Ch
Cmmg Upper Group Resolute Mk4 5.56x45 14.5'' P&w No Bcg Or Ch
1 of 1 images
Cmmg Upper Group Resolute Mk4 5.56x45 14.5'' P&w No Bcg Or Ch

Tap Tap to Zoom

Government Restriction Government Restriction
You May Also Like
Best Rated Magpul Industries PMAG GEN M2 MOE AR-15/M16/M4 Rifle Magazine, .223 Rem/5.56x45mm NATO, 30 Round, Black, 1 Pack, Polymer, MGMPI571BLK-30RD
Magpul Industries PMAG GEN M2 MOE AR-15/M16/M4 Rifle Magazine, .223 Rem/5.56x45mm NATO, 30 Round, Black, 1 Pack, Polymer, MGMPI571BLK-30RD
(48)
List: $12.95 $11.95 Save Up to $1.00
Best Rated Magpul Industries PMAG GEN M3 AR-15/M16/M4 Rifle Magazine w/Capacity Window, .223 Rem/5.56x45mm NATO, 30 Round, Black, 1 Pack, Polymer, MGMPI556BLK-30RD
Magpul Industries PMAG GEN M3 AR-15/M16/M4 Rifle Magazine w/Capacity Window, .223 Rem/5.56x45mm NATO, 30 Round, Black, 1 Pack, Polymer, MGMPI556BLK-30RD
(45)
List: $17.95 $16.95 Save Up to $1.00
Best Rated Magpul Industries PMAG GEN M3 AR-15/M16/M4 Rifle Magazine, .223 Rem/5.56x45mm NATO, 30 Round, Black, 1 Pack, Polymer, MGMPI557BLK-30RD
Magpul Industries PMAG GEN M3 AR-15/M16/M4 Rifle Magazine, .223 Rem/5.56x45mm NATO, 30 Round, Black, 1 Pack, Polymer, MGMPI557BLK-30RD
(29)
List: $14.95 $14.19
Best Rated Magpul Industries PMAG GEN M3 AR-15/M16/M4 Rifle Magazine, .223 Rem/5.56x45mm NATO, 30 Round, Coyote Tan, 1 Pack, Polymer, MAG557-MCT-30RD
Magpul Industries PMAG GEN M3 AR-15/M16/M4 Rifle Magazine, .223 Rem/5.56x45mm NATO, 30 Round, Coyote Tan, 1 Pack, Polymer, MAG557-MCT-30RD
(29)
List: $14.95 $14.19
Best Rated Magpul Industries PMAG GEN M3 AR-15/M16/M4 Rifle Magazine, .223 Rem/5.56x45mm NATO, 20 Round, Black, 1 Pack, Polymer, MAG560BLK-20RD
Magpul Industries PMAG GEN M3 AR-15/M16/M4 Rifle Magazine, .223 Rem/5.56x45mm NATO, 20 Round, Black, 1 Pack, Polymer, MAG560BLK-20RD
(21)
List: $14.95 $14.19
Best Rated Magpul Industries PMAG GEN M3 AR-15/M16/M4 Rifle Magazine, .223 Remington, 40 Round, Black, 1 Pack, Polymer, MGMPI233BLK-40RD
Magpul Industries PMAG GEN M3 AR-15/M16/M4 Rifle Magazine, .223 Remington, 40 Round, Black, 1 Pack, Polymer, MGMPI233BLK-40RD
(11)
List: $22.95 $20.45 Save Up to 11%
Best Rated Magpul Industries PMAG GEN M3 AR-15/M16/M4 Rifle Magazine w/Capacity Window, .223 Rem/5.56x45mm NATO, 30 Round, Coyote Tan, 1 Pack, Polymer, MAG556-MCT-30RD
Magpul Industries PMAG GEN M3 AR-15/M16/M4 Rifle Magazine w/Capacity Window, .223 Rem/5.56x45mm NATO, 30 Round, Coyote Tan, 1 Pack, Polymer, MAG556-MCT-30RD
(45)
List: $17.95 $16.95 Save Up to $1.00
Best Rated Strike Industries Rifle Magazine, AR-15, .223 Remington/5.56 NATO, 33 Round, Smoke Gray, 1 Pack, Polymer, SI-AR-MAG-33RD
Strike Industries Rifle Magazine, AR-15, .223 Remington/5.56 NATO, 33 Round, Smoke Gray, 1 Pack, Polymer, SI-AR-MAG-33RD
(10)
List: $26.99 $17.99 Save Up to 33%
Best Rated Magpul Industries PMAG GEN M2 MOE AR-15/M16/M4 Rifle Magazine w/Capacity Window, .223 Rem/5.56x45mm NATO, 30 Round, Black, 1 Pack, Polymer, MGMPI570BLK-30RD
Magpul Industries PMAG GEN M2 MOE AR-15/M16/M4 Rifle Magazine w/Capacity Window, .223 Rem/5.56x45mm NATO, 30 Round, Black, 1 Pack, Polymer, MGMPI570BLK-30RD
(12)
List: $15.95 $14.95 Save Up to $1.00
Coupon Available PMC Ammunition 556K X-Tac, 5.56x45mm NATO, 62 grain, Light Armor Piercing, Brass, Centerfire Rifle Ammo, 20, 5.56
PMC Ammunition 556K X-Tac, 5.56x45mm NATO, 62 grain, Light Armor Piercing, Brass, Centerfire Rifle Ammo, 20, 5.56
(108)
List: $14.99 $11.29 Save Up to 25%
Questions & Answers
Will this upper also take .223 rounds?

yes, only out of 5.56 barrels can you do that. but not the opposite.

by shrek, Verified Owner, February 9, 2026
View All Q&A You Have a Question? Ask!
Caliber:
5.56x45mm NATO
Overall Length:
23.8 in
Barrel Length:
14.5 in
Gas System Length:
Carbine Length
Barrel Twist Rate:
1-7
Threads per Inch:
1/2x28
Handguard Type:
M-LOK ATLAS S-ONE
Muzzle Device:
CMMG ZEROED SVD Brake Pinned & Welded
Finish:
Matte
Color:
Black
Handguard Length:
13.5 in

Code: 2CM-URC-55B360BAB-55B360B-AB

MPN: 55B360B-AB

UPC: 810148621926

List: $609.95Save 15%
$519.99

Buy Together and Save

OP Bucks$13.28

Product Info for CMMG Upper Group Resolute Mk4 5.56x45mm 14.5in P&W Upper Receiver

The CMMG Upper Group Resolute Mk4 5.56x45mm 14.5in P&W Upper Receiver was created to be the ideally suited item for anybody trying to find a high quality choice..image

Developed working with some of the very most robust and dependable components in existence, these AR15 Upper Receivers through CMMG can provide something that will give numerous years of dependability.

CMMG has been generating high quality products for a number of years, and the CMMG Upper Group Resolute Mk4 5.56x45mm 14.5in P&W Upper Receiver is their particular approach to demonstrating exactly how much they care.

At OpticsPlanet, we ensure that it is our obligation to get the best solution for all of your requirements, and featuring the CMMG Upper Group Resolute Mk4 5.56x45mm 14.5in P&W Upper Receiver is a thing that we are delighted to offer.

Specifications for CMMG Upper Group Resolute Mk4 5.56x45mm 14.5in P&W Upper Receiver:

Manufacturer: CMMG
Caliber: 5.56x45mm NATO
Overall Length: 23.8 in
Barrel Length: 14.5 in
Gas System Length: Carbine Length
Barrel Twist Rate: 1-7
Threads per Inch: 1/2x28
Handguard Type: M-LOK ATLAS S-ONE
Muzzle Device: CMMG ZEROED SVD Brake Pinned & Welded
Finish: Matte
Color: Black
Fabric/Material: Steel
Handguard Length: 13.5 in
Gun Make: AR Platform
Gun Model: AR-15
Weight: 4.1 lb
Bolt Carrier Group Included: No
Charging Handle Included: No

Package Contents:

  • CMMG Upper Group Resolute Mk4 5.56x45mm 14.5in P&W Upper Receiver

What firearm models does the manufacturer say CMMG Upper Group Resolute Mk4 5.56x45mm 14.5in P&W Upper Receiver is compatible with?

The manufacturer says that CMMG Upper Group Resolute Mk4 5.56x45mm 14.5in P&W Upper Receiver is compatible with AR-15

CMMG Upper Group Resolute Mk4 5.56x45mm 14.5in P&W Upper Receiver Orderable Models

List of Orderable Models

  • CMMG Upper Group Resolute Mk4 5.56x45mm 14.5in P&W Upper Receiver, No BCG or CH, AR-15, Black, 55B360B-AB , MPN: 55B360B-AB , UPC: 810148621926 , Code: 2CM-URC-55B360BAB-55B360B-AB
Compare (0)
1 item has been added
Add at least two items to compare