T
tehWildGingersmall things to mention
Reviewed on April 28, 2026Verified with Build
good stock but the adjustment lever was stiff for the first week of use
|
Geissele AR15/M4 Reaction Block (Mil-Spec Buffer Tube Only) 05-314
Click to see full view
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
MPN05-314
AssemblyTube Only
Buffer Tube SpecMil-Spec
August 2026 on GunPartPicker
Geissele AR15/M4 Reaction Block (Mil-Spec Buffer Tube Only) 05-314 ranked #15 of the 64 buffer tube kits builders added on GunPartPicker in August 2026. Builders have been adding it to their builds on GunPartPicker since February 2026. All time, it ranks #16 of the 136 buffer tube kits builders have added. Builds with this buffer tube assembly are mostly chambered in 5.56 NATO (77%, then .223 Wylde 12%), split between mid-length (58%) and carbine-length (21%) gas systems, and mostly AR-15 (94%).
Availability is good: it was in stock at one retailer or another nearly every day in August 2026, and today 3 of the 5 retailers we track have it in stock. The best price crept up from $189.99 to $204 over August 2026. Buying today, the lowest price is $189.99 at GritR Sports, which matches the best price we saw in August.
Updated · from real builds on GunPartPicker · Prices checked · refreshed daily across 31 retailers
Not sure which buffer tube assembly to pick?
We ranked every buffer tube assembly by how often it shows up in real builds on GunPartPicker.
Read the guide: AR-15 Buffer Tube Assembly Guide →Frequently Built With
The part most often added in each category by the 53 builds that include this one
Strike Industries Flat Wire Spring for AR Carbine - AR-FWS-C
Buffer Spring$20in 13 builds
Timber Creek Outdoors Ambidextrous Safety Selector - Black
Safety$20in 9 builds
LMT MARS-L Ambidextrous AR-15 Stripped Lower Receiver
Lower Receiver$352in 7 builds
Strike Industries AR-10 Shift Pins, Black - SI-AR10-SHIFT-BK
Takedown Pin$26in 13 builds
Phase 5 Version 2 Extended Bolt Release, 2.15" - EBRV2
Bolt Catch$60in 12 builds
Strike Industries Ambidextrous Magazine Release, Black - ARAMBIMRBK
Magazine Release$38in 7 builds
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.
93.8%
AR-1593.8%
AR-96.3%
CaliberBased on real build data showing which calibers builders choose alongside this product.
76.5%
5.56 NATO76.5%
.223 Wylde11.8%
.450 Bushmaster11.8%
Gas SystemBased on real build data showing which gas system lengths builders use with this product.
57.9%
Mid-Length57.9%
Carbine21.1%
Rifle15.8%
Pistol5.3%
Builds Featuring This Part
See all 5 →Builds in the community that include the Geissele AR15/M4 Reaction Block (Mil-Spec Buffer Tube Only) 05-314
| Build | Parts | Total |
|---|---|---|
 | 25 | $2558.11 |
 | 28 | $5519.19 |
 | 24 | $3996.65 |
 | 32 | $2872.41 |
 | 36 | $18145.54 |
Customer reviews
4.0out of 5
2 global ratings
Top reviews
I
i_likebuilding91Geissele reaction block heavy
Reviewed on March 26, 2026Verified with Build
Geissele AR15 reaction block fits a milspec buffer tube. Used for clamping uppers in a vise without marring. Heavier than I expected from a small accessory but the solid steel construction is reassuring. Worth it if you do your own armorer work.
|