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  3. Finish Your Lower Kit: FosTecH Echo Sport Binary Trigger for the AR-15 Platform + Mil-Spec Buffer Kit + AR-15 Carbine Recoil Buffer + KAK AR-15 "Lite" Lower Parts Kit + Adaptive Tactical AR-15 EX Performance Adjustable Stock

Finish Your Lower Kit: FosTecH Echo Sport Binary Trigger for the AR-15 Platform + Mil-Spec Buffer Kit + AR-15 Carbine Recoil Buffer + KAK AR-15 "Lite" Lower Parts Kit + Adaptive Tactical AR-15 EX Performance Adjustable Stock

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On sale $579.99 $359.99
Retail Price:$579.99
Your Savings:$220.00(38%)
Part Number: CO-83990
Availability: In Stock
Finish Your Lower Kit:
+FosTecH Echo Sport Binary Trigger for the AR-15 Platform
+AR-15 Mil-Spec Buffer Kit
+KAK AR-15 "Lite" Lower Parts Kit
+Adaptive Tactical AR-15 EX Performance Adjustable Stock

FosTecH Echo Sport Binary Trigger for the AR-15 Platform

Builders and Shooters know that the best upgrade you can do to your AR-15 is getting a reliable, smooth & light pull trigger. Thanks to the modularity of the AR-15 platform, upgrading your standard Mil-Spec Trigger with enhanced parts, or even a self contained all in one Drop-In trigger is as easy as punching out 2 pins from your lower receiver and ‘Dropping In’ your new upgrade. Binary triggers serve a special function of being able to increase the shooter's ability to shoot faster under a single action of the trigger. Binary triggers work by releasing the hammer when the trigger is pulled, and when the trigger is released. Binary Triggers are a great upgrade for standard AR-15 Rifles, and Pistol Caliber Carbines!

About this Trigger: The Fostech Echo Sport Trigger is more efficient, less complex, and most importantly LESS MONEY than other binary triggers. From an operational standpoint, the only difference the operator will notice is that the selector for the Echo operation is located inside the trigger well on a paddle. Move to the left for Echo Mode and move to the right for Semi-Automatic. The ECHO Sport is an economical pull and releases a trigger for the AR-15 platform. To explain how this trigger functions, every time you pull the trigger a bullet fires, and your BCG cycles a new round, when you release the trigger another bullet fires and your BCG then cycles another new round. This is not a machine gun, this is a single action for every round trigger which is the definition of semi-auto fire. One round per action on the trigger, once per pull, and once per release.

Compatibility: This trigger is designed to work with Mil-Spec AR-15 lower receivers and can be installed in just a few minutes!

Anti-Walk Pins: Not Included - This enhanced trigger is to be a direct replacement for your original trigger. Trigger pins are not included, but you can re-use the trigger pins from your standard lower parts kit.

Color: This trigger is Burnt Bronze accented.

Trigger Style: Standard M4 - This trigger uses a standard Mil-Spec curved trigger shoe.

Main Feature: Binary

Mil-Spec Buffer Tube

If you are in need of the 6-Position Aluminum 6061-T6 (buffer tube) Machined to Mil-Spec dimensions, we offer it separately. No other parts included just the tube.


Length: 7.25"

AR-15 Carbine Castle Nut

Standard Mil-Spec Castle Nut

Mil-Spec Receiver End Plate

Maintains Proper Alignment of Stock & Buffer Tube

M4-style receiver plate includes the engagement tab required to align the buttstock and buffer tube with the lower receiver on carbine models.

Precision, fine blanking process ensures precise edges and superior flatness for correct fit and solid installation.


Phosphate Finish

Made of 4140 Hardened Steel

AR-15 Carbine Recoil Spring

Made of the finest spring steel rated for 20,000+ rounds

AR-15 Carbine Recoil Buffer


Weighs 3 oz.

Standard carbine length buffer

Aluminum 6061-T6 exterior

Fits AR-15 and M16 carbine buffer tubes

Use with standard AR-15/M16 carbine buffer springs


3 oz. weight allows for more reliable function in rifles with shorter gas systems

3 oz. weight reduces bolt bounce in full auto fire

Increased weight also softens recoil

Standard dwell time for normal cycling of the rifle

KAK AR-15 "Lite" Lower Parts Kit

General Info: Lower Parts Kits include all of the small bits & pieces needed to make your AR-15 Lower fully functional. Such as the mag release, take-down pins, selector, trigger guard, bolt catch, buffer retainer, roll-pins, detents, and small springs are included to allow completion. This KAK Lower Parts Kit contains all of the necessary pieces needed to complete your build EXCEPT the trigger and components that go along with them. You can find triggers & fire control groups (HERE [https://www.omegamanufacturinginc.com/gun-triggers.html])

Brand: The 'Lite' Lower Parts Kit is produced by KAK Industries [https://www.omegamanufacturinginc.com/kak-industries-ar-products.html] with high-quality steel & brass components.

Brand Info: KAK Industry was founded and incorporated in 2011 by Kurt Kosman to address a gap in the firearms market for quality, American-Made components at affordable, sustainable prices. KAK began in one small shop, supplying specialty firearms components with innovative designs to shooters and hunters across America. Almost immediately, the demand for these products grew to such that a dedicated manufacturing facility was opened in Southern California, a major aerospace manufacturing hub.

Platform: Commercial AR-15

FCG Included: The 'Lite' Lower Parts Kit does NOT come with a hammer, hammer spring, trigger, trigger spring, disconnector, disconnector spring, or hammer & trigger pins. This kit is for completing your AR-15 lower and allowing an affordable parts kit in the case you already have drop-in triggers on-hand and ready to install.

Weight: The overall weight of the 'Lite' Lower Parts Kit is 0.335lbs.

Adaptive Tactical AR-15 EX Performance Adjustable Stock

General Info: We’re not all built the same, so why should our stock be? The Adaptive Tactical AR-15 EX Performance Adjustable Stock has easy to reach adjustment levers that allow users to adjust to the proper length of pull. Adjustable stocks are also an advantage in situations where groups of people are using the same rifle. The sling loops are molded into the stock so rusting won’t occur. There are also QD mounts with an oversized, high-strength adjustment pin. The non-slip, vented rubber buttpad provides extra grip and helps reduce felt recoil. The slick, innovative design is high strength and can easily be installed using household tools.

Brand: Adaptive Tactical - Adaptive Tactical infuses every product with over 40 years of firearm design and polymer engineering expertise. With a passion for stretching the boundaries of firearm innovation, Adaptive Tactical is driven to offer products focused on improving speed, performance, and versatility. Our passion for design and innovation is balanced with an unrelenting commitment to a quality product, uncompromising safety, and unmatched customer satisfaction. Our pledge to our customers is to provide products that not only meet the intended purpose but perform beyond expectations. We stand behind every Adaptive Tactical product and guarantee your satisfaction with the quality of workmanship and materials. Expect to be thrilled with your Adaptive Tactical purchase -- we'll settle for nothing less.

Model: AT EX Performance Adjustable Stock

Weight: This stock features an overall weight of 0.60 lbs.

Platform: AR-15 / 10

Buffer Tube Compatibility - Carbine Buffer Tube: This AT EX Performance Adjustable Stock fits on a Mil-Spec Carbine Buffer using only household tools to initially seat and secure into place. After seating, it can freely adjust to different positions.

QD Sling: The AT EX Performance Adjustable Stock comes with QD attachment points for solid sling mounting.

Sling Loop: The AT EX Performance Adjustable Stock features a sling loop for easy classic mounting without the need for extra hardware.

Buttpad: This stock has a hex rubber buttpad to lighten the felt recoil impulse directed to the shooter.

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