Geissele AR15/M4 Reaction Block (Mil-Spec Buffer Tube Only) 05-314
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Geissele
Overview
The Geissele AR15/M4 Reaction Block is a Mil-Spec buffer tube designed as a tube only assembly, providing a reliable foundation for your AR-15 build. This buffer tube is critical for proper function and cycling of the action, ensuring compatibility with Mil-Spec components and accessories. Commonly seen in builds featuring a mid-length gas system and chambered in 5.56 NATO, this component is essential for achieving a smooth and reliable shooting experience.
Specifications
Available Merchants(4)
Prices checked
Price Alert
October 2026 so far on GunPartPicker
Geissele AR15/M4 Reaction Block (Mil-Spec Buffer Tube Only) 05-314 ranks #18 of the 99 buffer tube kits builders have added on GunPartPicker so far in October 2026, behind the Geissele Automatics Premium Mil-Spec Buffer Tube Assembly With Super 42 H1 - Black, with about 1% of all buffer tube kits added to builds. Down from #17 in September. Builds with this buffer tube assembly are mostly chambered in 5.56 NATO (71%, then .223 Wylde 11%), split between mid-length (50%) and carbine-length (29%) gas systems, and mostly AR-15 (94%).
Today 3 of the 4 retailers we track have it in stock. Buying today, the lowest price is $210 at Brownells.
Updated · from real builds on GunPartPicker · Prices checked · refreshed daily across 37 retailers
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Frequently Built With
The part most often added in each category by the builds that include this one
Strike Industries Flat Wire Spring for AR Carbine - AR-FWS-C
Phase 5 Tactical AR-15 90 Degree Ambi Safety Selector Black
Sharps Bros Showdown Stripped Lower Receiver - Black, Unique Design and High-Performance for Custom AR Builds - SBLR11
Strike Industries AR-10 Shift Pins, Black - SI-AR10-SHIFT-BK
Strike Industries Ambidextrous Magazine Release, Black - ARAMBIMRBK
Geissele Automatics AR-15 SSA X Lightning Bow Trigger
Build Configuration Breakdown
Aggregated and anonymized data showing how builders use this product
PlatformBased on real build data showing which platform (AR-15, AR-10, AR-9) builders pair with this product.
CaliberBased on real build data showing which calibers builders choose alongside this product.
Gas SystemBased on real build data showing which gas system lengths builders use with this product.
Builds Featuring This Part
See all builds →Builds in the community that include the Geissele AR15/M4 Reaction Block (Mil-Spec Buffer Tube Only) 05-314
| Build | Parts | Total |
|---|---|---|
 | 25 | $2487.49 |
 | 28 | $5529.09 |
 | 24 | $4072.00 |
 | 32 | $2801.79 |
 | 36 | $18506.01 |
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