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Primary Weapons Systems
Primary Weapon Systems MK118 Mod 1-M Upper 6MM Arc 18 Ls Threaded
MSRP: $1,299.95$1,259.99 -
Primary Weapons Systems
Primary Weapons Brownells Exclusive MK1 Alpha Lt 223 Wylde Complete Upper - MK1 Alpha Lt 223 Wylde
$1,349.00 -
Primary Weapons Systems
Primary Weapons MK1 Alpha Lt 223 Wylde 14.5'' Barrel Complete Upper Receiver
$1,299.95 -
Primary Weapons Systems
Primary Weapons MK107 Mod 1-M 223 Wylde 7.75'' Barrel Complete Upper Receiver
$1,029.49 -
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Primary Weapons Systems
Primary Weapons MK109 Mod 2-M 300 Aac Blackout 9.75'' Barrel Complete Upper
$1,299.95 -
Primary Weapons Systems
Primary Weapons MK111 Mod 1-M Upper Receiver 11.85 Barrel .223 Wylde
$1,169.99 -
Primary Weapons Systems
Primary Weapons MK111 Pro 223 Wylde 11.85'' Barrel Complete Upper Receiver Black
$799.99 -
Primary Weapons Systems
Primary Weapons MK114 Mod 1-M 223 Wylde 14.5'' Barrel Complete Upper Thread Only
$1,029.49 -
Primary Weapons Systems
Primary Weapons MK114 Mod 2-M 223 Wylde 14.5'' Barrel Complete Upper Thread Only
$1,299.95 -
Primary Weapons Systems
Primary Weapons MK114 Mod 2-M 223 Wylde 14.5'' Barrel Complete Upper W/ Fsc 556
$1,299.95 -
Primary Weapons Systems
Primary Weapons MK116 Mod 1-M 7.62X39MM 16.1'' Barrel Complete Upper Receiver
MSRP: $1,049.95$1,029.49 -
Primary Weapons Systems
Primary Weapons MK116 Mod 1-M Upper Receiver 16.1 Barrel .223 Wylde
$1,169.99 -
Primary Weapons Systems
Primary Weapons MK116 Mod 2-M 223 Wylde 16.1'' Barrel Complete Upper W/ Fsc 556
$1,299.95 -
Primary Weapons Systems
Primary Weapons MK116 Mod 2-M 7.62X39MM 16.1'' Barrel Complete Upper W/ Fsc 556
$1,299.95 -
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Primary Weapons Systems
Primary Weapons MK218 Mod 1-M Upper Receiver 18'' Barrel 6.5 Creedmoor
$1,937.65 -
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Primary Weapons Systems
Primary Weapons PWS MK118 Mod 2-M Upper 6MM Arc 18 Ls Threaded
MSRP: $1,499.95$1,399.95 -
Primary Weapons Systems
Primary Weapons Systems MK109 Mod 1-M, Upper Receiver, Fits AR-15, 300 Blackout, 9.75" Barrel, 1:8" Twist
MSRP: $1,299.95$1,209.95
Upper Receivers
While the lower receiver is the foundation of the firearm, the upper receiver houses the components that most largely determine the performance of the rifle: the bolt carrier group and the barrel. Also, you can assemble a variety of upper configurations and use most with the same lower, meaning you only have one serialized firearm capable of shooting a variety of calibers.
Beginning Jan 1, 2026, California bill SB 704 requires all firearm barrels be transferred through a licensed FFL. AB1263 Requires all orders for NON-Barreled accesories be either verified or transferred through a licensed FFL.