Foxtrot Mike Products Complete Upper 8.5".45 ACP Glock Style - 8" M-LOK Rail - Blast Diffuser

SKU: FM45-8-5UR
MPN: FM45-8.5UR
Manufactured by Foxtrot Mike Products
5 Reviews


In Stock

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NOTE: This upper assembly has a barrel less than 16” in length. These uppers are intended for use in AR-15 pistols or legal short-barreled rifles. Other configurations may violate Federal law.

This Foxtrot Mike AR-15 pistol caliber carbine complete upper receiver comes with a huge assortment of features and improvements that can’t be had if you build yours from the ground up. With the FM products .45 ACP AR upper receiver, you get the functionality of a non-reciprocating side charging handle instead of the traditional T-handle. Now you can charge your SBR or pistol without coming off of your target. The upper receiver and handguard are a monolithic design with a proprietary lock system that ensures the rail won’t loosen over time. The slim free float handguard features the popular M-LOK system, so you can attach lights, rail sections, or other accessories. Underneath the 8” M-LOK handguard is an 8.5” 4150 chromoly barrel that has a 1:16 twist rate for stabilizing the .45 ACP projectile. This barrel comes with a FM products blast diffuser that eliminates the concussion to the side of your rifle for use at indoor ranges. Why build a .45 ACP AR-15 from the ground up when you can get a head start with this complete upper from Fox Trot Mike Products.


  • Non-reciprocating fixed forward charging handle
  • Left or right side charging
  • 8.5” 4150 chrome moly barrel
  • 8” monolithic free float handguard
  • M-Lok attachment points
  • Continuous picatinny top rail
  • .45 ACP bolt carrier group included
  • FM products blast diffuser with ½x36” threads
  • Compatible with Glock magazines

The FM products 45 caliber upper receiver is designed to be used with the FM pistol caliber lower receivers as well as other .45 Glock lower receivers that use Glock magazines. Build the ultimate pistol caliber carbine for the range or home defense with the Foxtrot Mike complete upper receiver assembly.

Feature rich, high-quality, and affordable, Foxtrot Mike Products offer cutting edge solutions utilizing the highest quality materials and manufacturing processes available.

Manufacturers Note: For optimal reliability, FM Products does not recommend using aluminum case ammo in their uppers or complete firearms.


Barrel Length8.5
Barrel Material4150 Chrome Moly Vanadium Steel
BrandFoxtrot Mike Products
Caliber Gauge.45 ACP
Gas System LengthBlowback
Gas System TypeBlowback
Handguard8 in M-LOK Rail
Muzzle DeviceFM Blast Diffuser
Twist Rate1:16

Mine won't run.

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I want to like mine but it won't run more than two or three shots without a jam with any of the three new Glock mags that I tried. I used a Spartan lower and a .45 buffer and spring kit and Stoner parts kit and an SB3 brace. It looks great but it won't run. I'm sure FM will help me get it right.

Lightweight and Handy

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Works great, I built my own charging handle. Very cool.

Love mine! Shooting sub sonic is a real joy, incredibly accurate too!


Love mine! I love mine and shooting subsonic is a joy, best quality pcc on the market, cant geat the price! I contacted FM, the new charging handle is why they are pricved the way they are. They offer a paratrooper style to anyone who wants them.

AR.45acp side forward charging handle

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l agree with Terry's comment regarding the difficulty using the charging handle without gloves, it is not user friendly due to its size and design, hopefully somebody will come up with a replacement soon. Otherwise would 've gotten the 5 stars.

Looks and functions excellent! Do not like charging handle.

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I like the upper's looks. I paired it with a New Frontier Armory lower. The upper & lower look and function good together except New Frontier's LRBHO is in their uppers, not lowers so that function does not work with this combo. It feeds well even JHP rounds. I put a shorter muzzle device and took about 2 inches off total length. However, I like the looks of original Blast Diffuser better and may change back. I gave it a 4/5 because the little plastic side charging handle is very uncomfortable without very thick gloves.