SIONICS Lower Receiver Extension Kit

from: $8995

The SIONICS Receiver Extension Kit is a collection of parts that can be used to upgrade or add to your AR-15 lower receiver. It includes a buffer tube, buffer spring, h buffer, castle nut, and end plate. These parts can be used to improve the performance of your rifle or to customize it to your liking.

SKU: S-REK Category: Product ID: 15719


The SIONICS Receiver Extension contains the following:

1- SIONICS 6-Position Mil-Spec Receiver Extension (Dry-Film Lubricated)
1- SIONICS QD Receiver End Plate
1 – SIONICS Receiver Extension Nut
1 – SIONICS H Buffer
1 – Sprinco Blue Action Spring

Optional Buffer Selection:

Upgrade to either an H2 or H3 Buffer

SIONICS Warranty

The SIONICS Warranty

All SIONICS Weapon Systems Firearms, Receivers and Parts are manufactured for a Lifetime of Hard Use. The definition of a Warranty is a Guarantee from a manufacturer that a defective product will be repaired or replaced.

SIONICS Parts Warranty (Barrels, BCGs, LPKs etc.)

All SIONICS Weapon Systems Parts carry our Guarantee against defects in original materials and workmanship. If any SIONICS product shows evidence of such defects, we will fix, repair, or replace your product with that of an equal value product. SIONICS Weapon Systems does not warranty products or damage caused to our products by the correct or incorrect installation of other manufacturer’s products. 


Step 1:

Call 520.396.3460 (Monday – Thursday 7:00 – 17:00 MST) and speak with one of our Excellent SIONICS staff to begin the troubleshooting process of your product. If deemed necessary you will then obtain an RMA# (Return Merchandise Authorization) to initiate the warranty claim. Outside of business hours please email us at

Step 2:

Once established that your item should return to SIONICS for further inspection, you will need to ship your defective/non-working item.

Return the item to our facility:
Make sure your assigned RMA# is clearly displayed on the outside of all return packages. This is necessary to match each package to the correct warranty claim. In addition please include a document listing your RMA#, Name, Phone Number as well as email address.

ATTN: Warranty Department
SIONICS Weapon Systems
5118 E. Pima Steet
Tucson, Arizona 85712

Step 3:

Our team here at SIONICS will work quickly to process your claim. Once your item is received, we will inspect and test within one business day. If the item is deemed defective, we will communicate back to you on your claim with the appropriate plan for repair or replacement.


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