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Knights SR-15 E3 Mod 1 Carbine W/URX Free Floating Rail

Knights SR-15 E3 Mod 1 Carbine W/URX Free Floating Rail

Knights SR-15 E3 Mod 1 Carbine W/URX Free Floating Rail

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You may contact us if you have questions about the exact specifications of this item.

ITEM #: KMC-30351
More Items From: Knights Armament

Knight's Armament Corp.

Stoner SR15 Mod 1 URX E3, 5.56/223, 16" Carbine


16" Chrome-Lined Barrel, URX 3.1 13.5" Rail, 2-Stage Trigger, Back Up Iron Sights, Adjustable Sopmod Stock, Black, 30 Rd Magazine

E3 Enhanced Bolt

The E3 Enhanced Bolt from Knight’s Armament features a number of components designed to make this bolt the most durable and reliable bolt available. It is a proprietary bolt specifically designed for our SR15 and 16 models. The E3 Bolt boasts several features that add to the its overall performance such as the enlarged bolt face, rounded lugs, reduced cam pin, and proprietary extractor and firing pin designs. 


This E3 Bolt is manufactured with an enlarged bolt face that provides more positive engagement in the chamber and lugs which are rounded to help to reduce chipping, cracking and snapping. This strengthened design helps to increase the life of the bolt and ensure a proper seating each time the weapon cycles. 

The E3 Bolt’s extractor design is also a unique achievement that helps to provide an extremely reliable component. It’s shaped like a rounded ‘T’ and sometimes referred to as a ‘butterfly’ shape. The pivot point of the extractor is shifted forward to help balance out the extractor and apply constant pressure on the shell which reduces cases of extraction failures. Another strong feature of the unique design of this extractor is the use of two full size extractor springs, as opposed to the standard micro spring. This allows for a reduction of relative compression while the extractor is in motion and provides a failsafe in case one spring fails. The bolt will continue to function properly and afford a user the opportunity to continue with their mission or firing schedule. 

The E3 Bolt is designed with a thinner Cam Pin and Firing Pin whose overall size has been reduced. The thinner Cam Pin allows for a thicker bolt web which is a common failure point in normal bolts. The reduction of the Firing Pin size is to accommodate the thinner Cam Pin. 

The full capabilities of the E3 Bolt are realized when exposed to full auto or extremely high cyclic firing rates yet the bolt performs gracefully under casual firing conditions. This component was designed to be exposed to the most stressful and unrelenting conditions and exceed expectations for durability and service life.

Ambidextrous Controls

Knight’s Armament designed this system to give shooters the maximum amount of options in their controls. Under this design all of the weapon’s major controls can be accessed from either side of the lower receiver. Left-handed shooters see the immediate benefits of being able to access the weapon’s controls in a more intuitive manner; however, there are a number of other benefits that right-handed shooters will enjoy under this system. 

Competition shooters benefit from these controls from the increase of speed that is achieved through components such as the right-side bolt catch. Trainers enjoy the variety of options because they can watch their trainee from either side of the weapon and even manipulate the weapon’s controls from the non-operating side. KAC has also introduced modifications to the design such as the scalloped safety selector switch. This allows a lower profile for the selector switch on the non-operating side of the receiver which helps to relieve any interference between the switch and a shooter’s glove or hand. For the maximum amount of configuration and operation options, Knight’s Ambidextrous Controls offer a sure solution.

Two-Stage Match Trigger

All of the weapons available from Knight’s Armament come equipped with a 4.5lb, 2-Stage Match Trigger. This type of trigger mechanism uses a system where, during the rearward squeeze of a trigger, it cycles through two stages of resistance

The first stage is a ‘no-poundage’ stage where hardly any resistance is felt during the rear-ward squeeze. There is a center point at which point resistance is felt and the second stage of the trigger begins. At this point, 4.5 pounds of force is required to squeeze the trigger through the second stage and cause the weapon to cycle. 

Our 2-stage trigger is meant to inform a shooter of exactly where their weapon is going to fire. This bolsters a firer’s confidence and can also assist in reducing trigger jerk, thereby increasing accuracy. The 4.5lb 2-Stage Trigger from Knight’s Armament is a highly calibrated and smooth component that is sure to be a welcome addition to any setup.

Universal Rail Extending (URX)

The evolution of the Universal Rail Extending (URX) begins over 20 years ago with Knight’s Armament pioneering the Modular Weapon System. Knight’s URX is a lightweight, free-floating, continuous top rail system that was designed to give a shooter the most diverse amount of placement options for any accessories they deemed helpful.

In an effort to relieve all weight, contact and stress from the barrel, the URX component was designed to be free-floating. This means that your barrel is not supporting or coming in contact with the rail system other than at the receiver. Under high firing rates, when the weapon’s barrel is heating up and undergoing greater amounts of stress, this system ensures accuracy is not affected by mounted accessories or a shooter’s manipulation of those accessories. 

Several variations of the URX are available depending on your needs. They come in a variety of lengths, from our URX Carbine at 7” to our URX 3.1 7.62 at 14”. Knight’s latest systems are the URX 3.1 systems which feature a flat continuous top rail, several inches of mounting rails at the fore and rear ends of the sides and bottom, and slick sided portions in the middle sections. These slick sided portions provide a slimmer diameter for grip as well as an overall reduction in weight. Some of our other models, such as the URX II variations, include full length side and bottom rails and integrated front sights. These components provide the most amount of options with the least amount of interference.


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