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Questions & Answers
Will this fit an Smith&wesson ar15 Featured Answer

Yes it will fit

by Josh, Verified Owner, June 15, 2019
Do the barrel threads on the FCR m-lok upper stick out far enough to mount a YHM QD flash suppressor and suppressor? Looks pretty close? Any input? Expert Answer

The Radical Firearms 10.5 in. 5.56 M4 Upper Assembly FCR handguard model has a 10.5" barrel and a 10" handguard. It may prevent the YHM QD Flash hider and suppressor from being mounted without contacting the handguard. Please email us at techsales@opticsplanet.com so we can get more information regarding your specific suppressor to see if it will be compatible.

by Hunter, Gear Expert, October 3, 2022
Customer Reviews
Helpful Positive Review Radical Firearms upper by Dale, January 24, 2023
This is my fourth Radical Firearms upper that I’ve purchased in two years and you cannot beat the quality for the price. No it’s not Daniel defense but it is a fraction of the price but don’t let the price deceive you you get great value for the mone...
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1/1 found this helpful
Helpful Positive Review Fit-n-finish, accuracy, Mil-Spec, Love it by Greg P., Verified Owner, August 16, 2019
I was building a budget AR pistol. I've built 16in ARs, but never an AR pistol. Built the pistol on an Anderson lower receiver. Because this build was based on a low budget, I located this lower assembly based on price comparison and features. Th...
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10/10 found this helpful
Helpful Positive Review Retired Vietnam vet by Colin, November 29, 2017
I'm please service was fast wish They Carried 9mm lower though nothing else needs to be said will continue to purchase as needed in the future find a cheaper to buy upper and lower rather than complete firearm
1/7 found this helpful
Helpful Positive Review Great pistol upper by Robrob, Verified Owner, April 27, 2018
Really nice upper. I liked the one with the m lok best. A nice slim feel to it. Everyone that handles it likes the balance with the SOB arm brace. Best one for the money anywhere. Can't go wrong here.
2/3 found this helpful
Helpful Positive Review Great Product by ForestRangerJoe, April 20, 2019
Put it on a firearm I was re-building and works great. Fit perfectly on my lower and couldn't ask for a better product. Shipping was impeccable and it arrived on schedule. I will definately buy more products from Optics Planet as I feel they offer...
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1/1 found this helpful
Helpful Negative Review Fair upper by Peter S., September 25, 2018
I purchased t bu is upper to complete my work gun. Everything works great and I do like it. However there is a problem with the barrel I encountered. While going through armored course I gauged the barrel and it is not 5.56 even though its stampe...
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4/12 found this helpful
Read All 7 Reviews

Product Discontinued by Manufacturer

Radical Firearms 10.5 in. 5.56 M4 Upper Assembly has been discontinued by Radical Firearms and is no longer available. Our product experts have helped us select these available replacements below.You can also explore other items in the Gun Parts, AR 15 Parts, Rifle Parts, AR15 Upper Receivers yourself to try and find the perfect replacement for you!

ATTENTION! Due to the configuration of products on this page, we are not able to support sales of these items to AK, CA, HI, IL, NY, WA, P.O. Boxes, and U.S. Territories.

Product Info for Radical Firearms 10.5 in. 5.56 M4 Upper Assembly

This Radical Firearms 10.5 in. 5.56 M4 Upper Assembly is a premium, law-enforcement-quality upper assembly, fitted with a 5.56 NATO chamber and A2 flash hider. These AR15 Upper Receivers by Radical Firearms are a direct drop-in replacement for your existing upper receiver, ensuring an optimized fit for maximum performance. This Radical Firearms 5.56 M4 Upper Assembly is outfitted with an integral KeyMod and Picatinny rail for easy access to mounting your favorite optics, lasers, bipods, and sights. A forged upper receiver and a melonite barrel make this upper one of the most durable and reliable on the market. However, it doesn't lack in details; this upper has an A2 flash hider, HPT/MPI, 5.56 NATO chamber, M4 feed ramps, a low profile micro gas block, a DGI stainless carbine-length gas tube, and an A2 flash hider wrapped around a 10.5in barrel. Install this Radical Firearms 10.5in 5.56 Barrel Upper Assembly onto your compatible AR-15 lower receiver to unleash a whole new world of powerful performance in the field.image

Package Contents:

  • Radical Firearms 10.5 in. 5.56 M4 Upper Assembly

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Radical Firearms 10.5 in. 5.56 M4 Upper Assembly Unavailable & Discontinued Models

List of Unorderable Models

Radical Firearms Upper Assembly 10.5 inch 5.56 M4 Contour, 10 inch FCR, A2 FH, w/o BCG and CH, Black, FU10.5-5.56M4-10FCR , MPN: FU10.5-5.56M4-10FCR , UPC: 816903024940 , Code: 2CS-UFH-105M4910-FU10-5-5-56M4-10FCR
Radical Firearms Upper Assembly 10.5 inch 5.56 M4 Contour, 10 inch FQR, w/o BCG and CH, Black, FU10.5-5.56M4-10FQR , MPN: FU10.5-5.56M4-10FQR , UPC: 814034024334 , Code: 2CS-UFH-105M4910-FU10-5-5-56M4-10FQR
Radical Firearms Upper Assembly 10.5 inch 5.56 M4 Contour, 9 inch FHR, w/o BCG and CH, Black, FU10.5-5.56M4-9FHR , MPN: FU10.5-5.56M4-9FHR , UPC: 814034024341 , Code: 2CS-UFH-105M4910-FU10-5-5-56M4-9FHR
Radical Firearms Upper Assembly 10.5 inch 5.56 M4 Contour, 10 inch FTR, w/o BCG and CH, Black, FU10.5-5.56M4-10FTR , MPN: FU10.5-5.56M4-10FTR , UPC: 814034024358 , Code: 2CS-UFH-105M4910-FU10-5-5-56M4-10FTR
Radical Firearms Upper Assembly 10.5 inch 5.56 M4 Contour, 10 inch FQR, w/BCG and CH, Black, CFU10.5-5.56M4-10FQR , MPN: CFU10.5-5.56M4-10FQR , UPC: 814034029827 , Code: 2CS-UFH-105M4910-CFU10-5-5-56M4-10FQR
Radical Firearms Upper Assembly 10.5 inch 5.56 M4 Contour, 9 inch FHR, w/BCG and CH, Black, CFU10.5-5.56M4-9FHR , MPN: CFU10.5-5.56M4-9FHR , UPC: 814034029834 , Code: 2CS-UFH-105M4910-CFU10-5-5-56M4-9FHR
Radical Firearms Upper Assembly 10.5 inch 5.56 M4 Contour, 10 inch FTR, w/BCG and CH, Black, CFU10.5-5.56M4-10FTR , MPN: CFU10.5-5.56M4-10FTR , UPC: 814034029841 , Code: 2CS-UFH-105M4910-CFU10-5-5-56M4-10FTR
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