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Guns For Sale - Hinterland Outfitters Online Gun Shop
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LWRC REPR Upper Receiver REPRU7BF16, 16" Spiral Fluted BBL, Black Finish

Hinterland Item #57435

Manufacturer Item #REPRU7BF16

LWRC REPR Upper Receiver REPRU7BF16, 16" Spiral Fluted BBL, Black Finish

Our Price: $2,334.00

Availability: Special Order

Estimated Lead Time 8-10 Weeks

PWS MK212 Mod1 Gas Piston Upper Receiver M212UC0B, .308 Win/7.62 Nato, 12.5 in BBL, 12 in KeyMod Rail, Blk Finish, Triad30 Brake

Hinterland Item #46585

Manufacturer Item #M212UC0B

PWS MK212 Mod1 Gas Piston Upper Receiver M212UC0B, .308 Win/7.62 Nato, 12.5 in BBL, 12 in KeyMod Rail, Blk Finish, Triad30 Brake

Our Price: $1,849.95

Availability: Special Order

PWS MK214 Mod1 Gas Piston Upper Receiver M214UC0B, .308 Win/7.62 Nato, 14.5 in BBL, 12 in KeyMod Rail, Blk Finish, FSC30 Brake

Hinterland Item #46586

Manufacturer Item #M214UC0B

PWS MK214 Mod1 Gas Piston Upper Receiver M214UC0B, .308 Win/7.62 Nato, 14.5 in BBL, 12 in KeyMod Rail, Blk Finish, FSC30 Brake

Our Price: $1,849.95

Availability: Special Order

PWS MK214 Mod1 Gas Piston Upper Receiver M214UC0BLE, .308 Win/7.62 Nato, 14.5 in BBL, 12 in KeyMod Rail, Blk Finish, Triad30 Brake

Hinterland Item #46587

Manufacturer Item #M214UC0BLE

PWS MK214 Mod1 Gas Piston Upper Receiver M214UC0BLE, .308 Win/7.62 Nato, 14.5 in BBL, 12 in KeyMod Rail, Blk Finish, Triad30 Brake

Our Price: $1,849.95

Availability: Special Order

PWS MK216 Mod1 Gas Piston Upper Receiver M216UC0B, .308 Win/7.62 Nato, 16.1 in BBL, 12 in KeyMod Rail, Blk Finish, FSC30 Brake

Hinterland Item #46588

Manufacturer Item #M216UC0B

PWS MK216 Mod1 Gas Piston Upper Receiver M216UC0B, .308 Win/7.62 Nato, 16.1 in BBL, 12 in KeyMod Rail, Blk Finish, FSC30 Brake

Our Price: $1,849.95

Availability: Special Order

PWS MK220 Mod1 Gas Piston Upper Receiver M220UC0B, .308 Win/7.62 Nato, 20 in BBL, 15 in KeyMod Rail, Blk Finish, PRC Brake

Hinterland Item #46589

Manufacturer Item #M220UC0B

PWS MK220 Mod1 Gas Piston Upper Receiver M220UC0B, .308 Win/7.62 Nato, 20 in BBL, 15 in KeyMod Rail, Blk Finish, PRC Brake

Our Price: $1,849.95

Availability: Special Order

POF-USA Upper Model P308 Gen 4 Regulated Gas Piston Recon 00621, 308 Win/7.62 NATO, 14.5 in Fluted BBL, M.R.R. Rail, NP3 Finish

Hinterland Item #50114

Manufacturer Item #00621

POF-USA Upper Model P308 Gen 4 Regulated Gas Piston Recon 00621, 308 Win/7.62 NATO, 14.5 in Fluted BBL, M.R.R. Rail, NP3 Finish

Manufacturer's MAP: $1,699.99

Call or Email For Our Price


Availability: Special Order

Estimated Lead Time 4-6 Weeks, Call or Email

POF-USA Upper Model P308 Gen 4 Regulated Gas Piston Recon 00622, 308 Win/7.62 NATO, 16.5 in Fluted BBL, M.R.R. Rail, Black Anodized Finish

Hinterland Item #50111

Manufacturer Item #00622

POF-USA Upper Model P308 Gen 4 Regulated Gas Piston Recon 00622, 308 Win/7.62 NATO, 16.5 in Fluted BBL, M.R.R. Rail, Black Anodized Finish

Manufacturer's MAP: $1,649.99

Call or Email For Our Price


Availability: Special Order

Estimated Lead Time 4-6 Weeks, Call or Email

H&K MR556 Complete Upper Receiver Kit 235975A5 , 223 Rem/5.56 NATO, 16" 4140 Steel Black BBL, Black Finish, Upper Only

Hinterland Item #43340

Manufacturer Item #235975A5

H&K MR556 Complete Upper Receiver Kit 235975A5 , 223 Rem/5.56 NATO, 16" 4140 Steel Black BBL, Black Finish, Upper Only

Our Price: $1,610.35

Availability: **Out of Stock**

POF-USA Upper ReVolt Heavy Gen 4 Regulated Gas Piston Recon 00763, 308 Win/7.62 NATO, 18 in Fluted BBL, M.R.R. Rail, NP3 Finish

Hinterland Item #50116

Manufacturer Item #00763

POF-USA Upper ReVolt Heavy Gen 4 Regulated Gas Piston Recon 00763, 308 Win/7.62 NATO, 18 in Fluted BBL, M.R.R. Rail, NP3 Finish

Manufacturer's MAP: $1,499.99

Call or Email For Our Price


Availability: Special Order

Estimated Lead Time 4-6 Weeks, Call or Email

POF-USA Upper Model P415 Gen 4 Regulated Gas Piston Recon 00823, 6.8 SPC, 16.5 in Fluted BBL, M.R.R. Rail, Black Anodized Finish

Hinterland Item #50125

Manufacturer Item #00823

POF-USA Upper Model P415 Gen 4 Regulated Gas Piston Recon 00823, 6.8 SPC, 16.5 in Fluted BBL, M.R.R. Rail, Black Anodized Finish

Manufacturer's MAP: $1,509.99

Call or Email For Our Price


Availability: Special Order

Estimated Lead Time 4-6 Weeks, Call or Email

PWS MK1 Mod1 Gas Piston Upper Receiver M107UA0B, .223 Wylde, 7.75 in BBL, 7 in KeyMod Rail, Blk Finish, Triad556 Brake

Hinterland Item #46575

Manufacturer Item #M107UA0B

PWS MK1 Mod1 Gas Piston Upper Receiver M107UA0B, .223 Wylde, 7.75 in BBL, 7 in KeyMod Rail, Blk Finish, Triad556 Brake

Our Price: $1,399.95

Availability: Special Order

PWS MK1 Mod1 Gas Piston Upper Receiver M110UA0B, .223 Wylde, 12.75 in BBL, 12 in KeyMod Rail, Blk Finish, Triad556 Brake

Hinterland Item #46577

Manufacturer Item #M112UA0B

PWS MK1 Mod1 Gas Piston Upper Receiver M110UA0B, .223 Wylde, 12.75 in BBL, 12 in KeyMod Rail, Blk Finish, Triad556 Brake

Our Price: $1,399.95

Availability: Special Order

PWS MK1 Mod1 Gas Piston Upper Receiver M110UB0B, .300 Blackout, 12.75 in BBL, 12 in KeyMod Rail, Blk Finish, Triad556 Brake

Hinterland Item #46578

Manufacturer Item #M112UB0B

PWS MK1 Mod1 Gas Piston Upper Receiver M110UB0B, .300 Blackout, 12.75 in BBL, 12 in KeyMod Rail, Blk Finish, Triad556 Brake

Our Price: $1,399.95

Availability: Special Order

PWS MK1 Mod1 Gas Piston Upper Receiver M114UA0B, .223 Wylde, 14.5 in BBL, 12 in KeyMod Rail, Blk Finish, Pinned FSC556 Brake

Hinterland Item #46579

Manufacturer Item #M114UA0B

PWS MK1 Mod1 Gas Piston Upper Receiver M114UA0B, .223 Wylde, 14.5 in BBL, 12 in KeyMod Rail, Blk Finish, Pinned FSC556 Brake

Our Price: $1,399.95

Availability: Special Order

PWS MK1 Mod1 Gas Piston Upper Receiver M114UA0BLE, .223 Wylde, 14.5 in BBL, 12 in KeyMod Rail, Blk Finish, Pinned Triad556 Brake

Hinterland Item #46580

Manufacturer Item #M114UA0BLE

PWS MK1 Mod1 Gas Piston Upper Receiver M114UA0BLE, .223 Wylde, 14.5 in BBL, 12 in KeyMod Rail, Blk Finish, Pinned Triad556 Brake

Our Price: $1,399.95

Availability: Special Order

PWS MK1 Mod1 Gas Piston Upper Receiver M114UA0BNC, .223 Wylde, 14.5 in BBL, 12 in KeyMod Rail, Blk Finish, No Brake, (NFA Rules Apply)

Hinterland Item #46581

Manufacturer Item #M114UA0BNC

PWS MK1 Mod1 Gas Piston Upper Receiver M114UA0BNC, .223 Wylde, 14.5 in BBL, 12 in KeyMod Rail, Blk Finish, No Brake, (NFA Rules Apply)

Our Price: $1,399.95

Availability: Special Order

PWS MK1 Mod1 Gas Piston Upper Receiver M116UA0B, .223 Wylde, 16.1 in BBL, 12 in KeyMod Rail, Blk Finish, Pinned Triad556 Brake

Hinterland Item #46582

Manufacturer Item #M116UA0B

PWS MK1 Mod1 Gas Piston Upper Receiver M116UA0B, .223 Wylde, 16.1 in BBL, 12 in KeyMod Rail, Blk Finish, Pinned Triad556 Brake

Our Price: $1,399.95

Availability: Special Order

PWS MK1 Mod1 Gas Piston Upper Receiver M116UA0B, .223 Wylde, 18 in BBL, 15 in KeyMod Rail, Blk Finish, Pinned Triad556 Brake

Hinterland Item #46584

Manufacturer Item #M118UA0B

PWS MK1 Mod1 Gas Piston Upper Receiver M116UA0B, .223 Wylde, 18 in BBL, 15 in KeyMod Rail, Blk Finish, Pinned Triad556 Brake

Our Price: $1,399.95

Availability: Special Order

PWS MK1 Mod1 Gas Piston Upper Receiver M116UB0B, .300 Blackout, 16.1 in BBL, 12 in KeyMod Rail, Blk Finish, Pinned Triad30 Brake

Hinterland Item #46583

Manufacturer Item #M116UB0B

PWS MK1 Mod1 Gas Piston Upper Receiver M116UB0B, .300 Blackout, 16.1 in BBL, 12 in KeyMod Rail, Blk Finish, Pinned Triad30 Brake

Our Price: $1,399.95

Availability: Special Order

POF-USA Upper Model P415 Gen 4 Regulated Gas Piston Recon 00617, 223 Win/5.56 NATO, 18 in Fluted BBL, M.R.R. Rail, NP3 Finish

Hinterland Item #50120

Manufacturer Item #00617

POF-USA Upper Model P415 Gen 4 Regulated Gas Piston Recon 00617, 223 Win/5.56 NATO, 18 in Fluted BBL, M.R.R. Rail, NP3 Finish

Manufacturer's MAP: $1,379.99

Call or Email For Our Price


Availability: Special Order

Estimated Lead Time 4-6 Weeks, Call or Email

PWS MK1 Mod1 Gas Piston Upper Receiver M110UA0B, .223 Wylde, 10.75 in BBL, 10 in KeyMod Rail, Blk Finish, Triad556 Brake

Hinterland Item #46576

Manufacturer Item #M110UA0B

PWS MK1 Mod1 Gas Piston Upper Receiver M110UA0B, .223 Wylde, 10.75 in BBL, 10 in KeyMod Rail, Blk Finish, Triad556 Brake

Our Price: $1,379.95

Availability: Special Order

Wilson TR68RCF16UP Upper 6.8mm 16" 416 Stainless Fluted Barrel Black

Hinterland Item #62769

Manufacturer Item #TR68RCF16UP

Wilson TR68RCF16UP Upper 6.8mm 16" 416 Stainless Fluted Barrel Black

Our Price: $1,262.98

Availability: In Stock

Wilson TR300RCS14UP Upper 300 AAC Blackout 14.7" 416 Stainless Fluted Barrel Blk

Hinterland Item #62768

Manufacturer Item #TR300RCS14UP

Wilson TR300RCS14UP Upper 300 AAC Blackout 14.7" 416 Stainless Fluted Barrel Blk

Our Price: $1,256.33

Availability: **Out of Stock**

POF-USA Upper ReVolt Light Gen 4 Regulated Gas Piston Recon 00757, 223 Win/5.56 NATO, 18 in Fluted BBL, M.R.R. Rail, NP3 Finish

Hinterland Item #50124

Manufacturer Item #00757

POF-USA Upper ReVolt Light Gen 4 Regulated Gas Piston Recon 00757, 223 Win/5.56 NATO, 18 in Fluted BBL, M.R.R. Rail, NP3 Finish

Manufacturer's MAP: $1,249.99

Call or Email For Our Price


Availability: Special Order

Estimated Lead Time 4-6 Weeks, Call or Email

POF-USA Upper Model P415 Gen 4 Regulated Gas Piston Recon 00614, 223 Win/5.56 NATO, 16.5 in Fluted BBL, M.R.R. Rail, Black Anodized Finish

Hinterland Item #50118

Manufacturer Item #00614

POF-USA Upper Model P415 Gen 4 Regulated Gas Piston Recon 00614, 223 Win/5.56 NATO, 16.5 in Fluted BBL, M.R.R. Rail, Black Anodized Finish

Manufacturer's MAP: $1,339.99

Call or Email For Our Price


Availability: Special Order

Estimated Lead Time 4-6 Weeks, Call or Email

Wilson TR223SS20UP Upper .223 Wylde 20" 416 Stainless Fluted Barrel Black

Hinterland Item #62767

Manufacturer Item #TR223SS2OUP

Wilson TR223SS20UP Upper .223 Wylde 20" 416 Stainless Fluted Barrel Black

Our Price: $1,219.45

Availability: **Out of Stock**

2A Armament BALIOS-LITE, Upper, 223 Rem, 556NATO, 16", Black, 416-R Stainless Steel With QPQ Nitride Finish, AR Rifles 2A-CU55616ML15BLK-1

Hinterland Item #71302

Manufacturer Item #2A-CU55616ML15BLK-1

2A Armament BALIOS-LITE, Upper, 223 Rem, 556NATO, 16", Black, 416-R Stainless Steel With QPQ Nitride Finish, AR Rifles 2A-CU55616ML15BLK-1

Our Price: $1,207.80

Availability: **Out of Stock**

Daniel Defense M4A1 Upper, 223 Rem/556NATO, 16" (14.5" with Pinned Brake) Barrel, 1:7 Twist, with M4 12.0 Rail, Flat Dark Earth Finish 23-004-13150

Hinterland Item #71816

Manufacturer Item #23-004-13150

Daniel Defense M4A1 Upper, 223 Rem/556NATO, 16" (14.5" with Pinned Brake) Barrel, 1:7 Twist, with M4 12.0 Rail, Flat Dark Earth Finish 23-004-13150

Manufacturer's MAP: $1,216.00

Add to Cart To View Our Low Price


Availability: **Out of Stock**

Ruger SR556UFB 90356 Complete Upper 5.56 16.12" 41V45 Steel Heavy Contour Blk Brl, Thread BBL

Hinterland Item #43341

Manufacturer Item #90356

Ruger SR556UFB 90356 Complete Upper 5.56 16.12" 41V45 Steel Heavy Contour Blk Brl, Thread BBL

Our Price: $1,090.10

Availability: **Out of Stock**

Daniel Defense 23-004-08013-011 DDMK18 223 Remington/5.56 NATO 10.3" Chrome Moly Steel Cold Hammer Forged  Brl Finish

Hinterland Item #62737

Manufacturer Item #23-004-08013-011

Daniel Defense 23-004-08013-011 DDMK18 223 Remington/5.56 NATO 10.3" Chrome Moly Steel Cold Hammer Forged Brl Finish

Manufacturer's MAP: $1,146.00

Add to Cart To View Our Low Price


Availability: In Stock

Spikes STU5420-S2S ST-15 LE Mid Upper 5.56 14.5" 12" SAR3 Quad Rail Blk

Hinterland Item #62761

Manufacturer Item #STU5420S2S

Spikes STU5420-S2S ST-15 LE Mid Upper 5.56 14.5" 12" SAR3 Quad Rail Blk

Our Price: $1,010.70

Availability: In Stock

Spikes STU5420-S9S ST-15 LE Mid Upper 5.56 14.5" 9" SAR3 Quad Rail Blk

Hinterland Item #62762

Manufacturer Item #STU5420S9S

Spikes STU5420-S9S ST-15 LE Mid Upper 5.56 14.5" 9" SAR3 Quad Rail Blk

Our Price: $1,001.70

Availability: In Stock

POF-USA Upper Model P415 EDGE 01309, 223 Win/5.56 NATO, 16.5 in Fluted BBL, M-LOK Rail, Black Anodized Finish

Hinterland Item #50121

Manufacturer Item #01309

POF-USA Upper Model P415 EDGE 01309, 223 Win/5.56 NATO, 16.5 in Fluted BBL, M-LOK Rail, Black Anodized Finish

Our Price: $999.00

Availability: In Stock

Primary Weapons 2M114UA0B MK116 223 Wylde 16" 4140 Steel Heavy Full Black Bbl Finish

Hinterland Item #62747

Manufacturer Item #2M116UA0B

Primary Weapons 2M114UA0B MK116 223 Wylde 16" 4140 Steel Heavy Full Black Bbl Finish

Our Price: $997.68

Availability: In Stock

Primary Weapons 2M118UA0B MK118 223 Wylde 18" 4140 Steel Threaded Black Bbl Finish

Hinterland Item #62748

Manufacturer Item #2M118UA0B

Primary Weapons 2M118UA0B MK118 223 Wylde 18" 4140 Steel Threaded Black Bbl Finish

Our Price: $997.68

Availability: In Stock

Primary Weapons M116UF0B MK114 223 Wylde 14" 4140 Steel Black Bbl Finish

Hinterland Item #62746

Manufacturer Item #2M114UA0B

Primary Weapons M116UF0B MK114 223 Wylde 14" 4140 Steel Black Bbl Finish

Our Price: $997.68

Availability: In Stock

DRD Tactical DRDU300 U556 300 AAC Blackout/Whisper 16" Black Barrel

Hinterland Item #62780

Manufacturer Item #DRDU300

DRD Tactical DRDU300 U556 300 AAC Blackout/Whisper 16" Black Barrel

Our Price: $995.57

Availability: In Stock

Nordic Components Upper, 300 Blackout, 16", Black, 1:8, NC-3 Free Float M-LOK Handguard NC15U-300-16BK-RFL

Hinterland Item #73078

Manufacturer Item #NC15U-300-16BK-RFL

Nordic Components Upper, 300 Blackout, 16", Black, 1:8, NC-3 Free Float M-LOK Handguard NC15U-300-16BK-RFL

Our Price: $982.34

Availability: In Stock

POF-USA Upper Model P15 Puritan 00728, 223 Win/5.56 Nato, 16.5 in BBL, Black Finish

Hinterland Item #50123

Manufacturer Item #00728

POF-USA Upper Model P15 Puritan 00728, 223 Win/5.56 Nato, 16.5 in BBL, Black Finish

Manufacturer's MAP: $979.99

Call or Email For Our Price


Availability: Special Order

Estimated Lead Time 4-6 Weeks, Call or Email

Daniel Defense M4 Volume 9 Upper, Fits AR Rifles, 223 Rem/556NATO, 16" HF Barrel, 1:7  Twist, Daniel Defense Furniture, with M4 15.0 Rail, Black Finish 23-145-18027-047

Hinterland Item #71818

Manufacturer Item #23-145-18027-047

Daniel Defense M4 Volume 9 Upper, Fits AR Rifles, 223 Rem/556NATO, 16" HF Barrel, 1:7 Twist, Daniel Defense Furniture, with M4 15.0 Rail, Black Finish 23-145-18027-047

Manufacturer's MAP: $1,076.00

Add to Cart To View Our Low Price


Availability: In Stock

Nordic Components Upper, .223 WYLDE, 556NATO, 16", Black, 1:8, NC-3 Free Float M-LOK Handguard NC15U-223-16BK-RFL

Hinterland Item #73075

Manufacturer Item #NC15U-223-16BK-RFL

Nordic Components Upper, .223 WYLDE, 556NATO, 16", Black, 1:8, NC-3 Free Float M-LOK Handguard NC15U-223-16BK-RFL

Our Price: $947.93

Availability: In Stock

DRD Tactical DRDU556 U556 223 Rem/5.56 NATO 16" Black Barrel Finish

Hinterland Item #62781

Manufacturer Item #DRDU556

DRD Tactical DRDU556 U556 223 Rem/5.56 NATO 16" Black Barrel Finish

Our Price: $933.75

Availability: In Stock

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Upper Receivers

An upper receiver refers to the front and top section of an AR-style rifle. An AR-15 upper receiver contains about 80% of the rifle’s functionality, including the fore stock, forward assist, charging handle, barrel, gas operating system, bolt and bolt carrier assembly. Most upper receivers are MISPEC, meaning you can use them with many different lower receivers, and it allows you to easily transition between barrel lengths, AR-15 parts and calibers.

When you’re ready to begin building your own MSR rifle, be sure to take a look at some of the most popular upper receiver brands, including:

  • Spikes Tactical
  • Midwest Industries
  • Sig Sauer
  • Smith and Wesson
  • Colt
  • POF
  • Armalite
  • Daniel Defense
  • CMMG
  • Bravo Company
  • Troy Industries
  • Seekins Precision
  • Noveske Rifleworks
  • 2A Armament
  • Barrett

 Anatomy of an Upper Receiver

Before you can decide which upper receiver is right for you, it’s good to understand the major components and differences between them.

  • Operating System: One of the key features and major differences between upper receivers is the operating system. There are essentially two operating systems to choose from with AR-15 rifles—direct gas impingement and gas piston technology. The original AR-15 system, designed by Eugene Stoner, was direct gas impingement (DGI). When the trigger is pulled in a DGI gas system, propellant gas is channeled through a small hole in the barrel, then a tube to where it can directly contact (or impinge) the bolt carrier mechanism. The gas is then pushed toward the rear of the rifle, extracting and ejecting the spent case. The gas is then pushed forward by means of spring-loaded action, and it strips a new round from the cartridge, loading it in the chamber to be fired.

Gas piston technology was first used by Mikhail Kalashnikov with the AK-47, the AR-15’s first rival. Gas piston technology works similarly to DGI, except that the gas is fed into a separate cylinder within the barrel. Within the cylinder, it forces a piston back that pushes the bolt carrier to extract and eject the spent case, and spring-action (like DGI) pushes it back into position while loading a new round.

  • Barrel: The barrel of your upper receiver is one of the most important components to ensure the best possible shooting experience. Barrels play a key role in accuracy of the rifle. Keep in mind that all barrels must be at least 16 inches in accordance with federal law. Anything less than 16 inches is considered an NFA firearm and will require a tax stamp and additional ATF paperwork. Modern AR-15 upper receivers can be fitted with a variety of barrel lengths, ranging from 14-inch carbine barrels to 24-inch target and long-range barrels. Early AR-15 barrels had a twist rate of 1:12 for the .223 Remington, but most modern AR-15s have a 1:7, 1:8 or 1:9 twist rate. The twist rate of a barrel is designed to stabilize the bullet as it passes through the barrel, and every bullet is designed to function with a specific twist rate, so make sure to match the twist rate of your barrel to the bullet you are using.
  • Bolt Carrier Group: This group of components within the upper receiver is responsible for loading the rifle as well as firing correctly and ejecting spent rounds. It is recommended to purchase a fully intact bolt carrier group with your upper receiver, but if you have more expertise and skill, you can assemble your own, which would include a firing pin, bolt, cam pin, extractor and gas key.
  • Charging Handle: The charging handle allows you to manually pull the bolt carrier group back. There are two reasons for this: One, you use the charging handle to load the first round of a new magazine, and two, if a round doesn’t fire properly, you can use the charging handle to expel the faulty load and replace it. The charging handle otherwise remains stationary during normal firing.
  • Forward Assist: You’ll find yourself rarely using this component of your upper receiver. The forward assist is mostly there to ensure dependability. If your bolt happens to not close all the way, you can push the forward assist to close it. Many riflemen do not find the forward assist necessary on modern upper receivers, but it is always there just in case you need it.
  • Rail System and Handguard: You’ll find a large number of handguards and rails to further customize your new AR-15 upper receiver. Handguards and rail covers protect your hand from the heat generated in the barrel as you fire your rifle. Many modern handguards are referred to as rail systems as they come with more points to attach accessories and further customize your rifle. Rail systems and rail kits are great for customizing your rifle, and the most common rail system is the Picatinny rail. With a rail system on your upper receiver, you can easily attach lasers, flashlights, optics, grips, sights and bi-pods.
  • Ejection Port Cover: The purpose of the ejection port cover is to keep the bolt carrier group and internal components of your upper receiver clean. When firing, the ejection port cover opens through the backward movement of the bolt carrier group. If you want it closed, you’ll have to manually shut it. Keeping the ejection port carrier closed when not using the rifle helps prevent dirt and other debris from getting inside your upper receiver.

Variations

While browsing AR-15 upper receivers, there are a few variations you’ll run into and want to consider when trying to choose the best AR setup for you.

  • M4 Feed Ramps: The M4 feed ramp is a modification to the standard AR feed ramp. A standard AR feed ramp is a 45-degree cut into the bottom of the breech of the barrel, while the M4 feed ramp is a 52-degree cut that extends all the way to the bottom of the upper receiver. The shallower angle of the M4 feed ramp allows for smoother and more efficient loading and firing of longer, pointier ammunition.
  • MPI/HPT: While looking at popular upper receivers, you’ll find most saying that they are MPI and HPT tested. To put this in layman’s terms, MPI stands for magnetic particle inspection, and HPT stands for high pressure tested. MPI looks for defaults within the upper receiver that may cause it to malfunction, and HPT ensures the upper receiver and bolt carrier group is able to handle the pressures created when firing high magnitude rounds.
  • A2 Upper: An A2-style upper receiver is aesthetically more like the original Colt AR-15. It has a fixed handle on the top that incorporates a rear sight that is adjustable for both wind and elevation.
  • A4 Upper: A4 upper receivers are often called “flat tops” due to their flat upper surface. Unlike the A2 uppers, the flat accessory rail on the A4 allows for a wider variety of attachments, including an A2-style handle. Further, the A4 upper receiver includes an M4 style feed ramps. You will find that most modern AR-15 components come with M4 feed ramps as a standard.

Muzzle Devices

Muzzle devices can be added to the muzzle of an AR upper receiver to enhance your shooting experience. Popular muzzle devices include compensators, muzzle brakes and flash hiders.

  • Compensators: Compensators help to prevent muzzle climb and improve accuracy by venting gases from the barrel upward and out.
  • Muzzle Brakes: Muzzle brakes help to reduce recoil by up to 40% and improve accuracy by venting gases horizontally. This further reduces muzzle climb while providing a clear line of vision for follow-up shots.
  • Flash Hiders: When firing, gunpowder combustion produces a flash of light as the bullet leaves the barrel. This muzzle flash can give away your position as well as briefly hinder your line of vision. Flash hiders help to counter these disadvantages.

 Sights and Optics

Finally, you’ll want to take a gander at the wide variety of sights and optics available to attach to your upper receiver. From red dot sights to high magnitude scopes, there are many options available to you for your AR-15. Browse our selection of scopes and optics to find the right sight for you. Also, lasers and lights are very common accessories for AR-15s and other modern sporting rifles. They are great for law enforcement, home defense and target practice.

Buyer Considerations and Building Your Own AR

Hinterland Outfitters offers all the best brands for AR-15 upper receivers and AR-15 accessories. Our award-winning customer service team is ready to help you today, so don’t hesitate to contact us with all your questions and needs. We will help you choose the right upper receiver and build the perfect AR-15 for you.

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