The Phase 5 Tactical Pistol Buffer Tube (PBT), UPC 813318020406, is a premium AR-15 pistol receiver extension engineered for builders who demand rock-solid reliability, Mil-Spec compatibility, and clean, low-profile ergonomics. Designed specifically for AR-15 pistol builds, this CNC-machined aluminum buffer tube pairs perfectly with a Mil-Spec carbine buffer and spring, delivering smooth cycling and a rugged platform for your brace or foam cheek rest. GrabAGun+1
Whether you’re finishing a compact truck gun, a defensive AR pistol, or a lightweight range blaster, the Phase 5 PBT gives you the strength, finish quality, and smart design you want at the back of your build.
CNC-Machined Billet Aluminum – Built for Hard Use
At the core of the PBT is a CNC-machined billet aluminum buffer tube, built to handle the demands of high-round-count AR pistols. The same tube is used in Phase 5’s complete assembly, where it’s specified as 7075-T6/7075-T651 aluminum, giving you excellent strength-to-weight and resistance to deformation under recoil. phase5wsi.com+2OpticsPlanet+2
Precision machining ensures true concentricity and straightness, reducing drag on the buffer and spring.
Designed from the ground up to fit Mil-Spec carbine buffers and springs, so you can use standard-quality internals instead of oddball proprietary parts. GrabAGun+1
If you’re upgrading from a no-name pistol tube or starting a premium build from scratch, Phase 5’s billet construction is a serious step up.
Mil-Spec Type III Hardcoat Anodized – Classic Tactical Black
The PBT wears a Mil-Spec Type III hardcoat anodized black finish, the same finish class trusted on quality receivers and duty-grade components. GrabAGun+1
Benefits of this finish include:
Exceptional wear resistance under sling rub, brace contact, and regular handling
Corrosion resistance in wet or humid environments
A low-sheen matte black appearance that blends seamlessly with most AR lowers and accessories
If you want your AR pistol to look as good as it runs, this hardcoat anodizing is the way to go.
Machined Lower Slot – Ready for Mil-Spec End Plates & Sling Mounts
Phase 5 thoughtfully machines a lower slot into the buffer tube to maximize compatibility with common hardware. GrabAGun+2vtsupply-com.3dcartstores.com+2
That slot:
Accepts all Mil-Spec end plates, so you can run standard or QD sling plates without fitment headaches
Works with sling mounting accessories designed around traditional carbine receiver extensions
Helps ensure a secure mechanical lockup when the castle nut is properly torqued and staked
This makes the PBT a plug-and-play option with most quality AR lower parts kits and sling setups.
Includes End Plate, Castle Nut & Foam Rest Pad – Ready Out of the Box
Unlike bare tubes that require extra purchases, the Phase 5 PBT package includes everything you need at the rear of the lower (buffer and spring sold separately): GrabAGun+2vtsupply-com.3dcartstores.com+2
Pistol Buffer Tube (PBT)
Mil-Spec Castle Nut
Mil-Spec End Plate
Foam Rest Pad
The foam rest pad is constructed from NPVC/NBR nitrile, a highly durable rubber foam with excellent abrasion resistance, tensile strength, and resistance to oils and fuels. It’s designed to handle temperatures from about –20°F to +220°F, and is engineered with antidegradants to resist UV and ozone breakdown. vtsupply-com.3dcartstores.com+1
That means a comfortable, long-lasting cheek weld on your AR pistol that won’t turn gummy or crumble after a season of use.
Pistol-Length Tube with Ideal Dimensions for AR Pistols
The Phase 5 PBT is a true pistol-length buffer tube, sharing the same geometry as the complete assembly:
These dimensions give you:
A compact overall profile ideal for AR pistols
Plenty of tube length for a stable cheek weld with the included foam pad
Compatibility with many pistol stabilizing braces that clamp or strap to 1.25" tubes (always confirm fit and current laws/regulations). OpticsPlanet+1
Compatible with Mil-Spec Carbine Buffer & Spring
One of the best features of the PBT is that it’s built to work with standard Mil-Spec carbine buffers and springs, not proprietary internals. GrabAGun+2vtsupply-com.3dcartstores.com+2
That means you can:
Use the carbine buffer and spring you trust or tune your pistol with heavier or lighter buffer setups as needed
Easily source replacement parts anywhere Mil-Spec AR components are sold
Avoid weird cycling issues tied to odd-length or mystery buffer systems
For builders who like to tune gas and recoil impulse, this flexibility is a big win.
Ideal for AR-15 Pistol Builds, Conversions & Upgrades
The Phase 5 Tactical Pistol Buffer Tube PBT is a perfect choice for:
New AR-15 pistol builds where you want a robust, high-quality rear end from the start
Upgrading budget pistol tubes that lack proper machining or finish
Replacing worn or damaged tubes with a billet, hard-anodized Mil-Spec solution
Builders who want a foam-pad cheek rest included instead of buying multiple pieces separately
Matched with a good lower, quality LPK, and your preferred buffer/spring, the PBT becomes the backbone of a reliable, comfortable AR pistol.
Key Features & Specifications – Phase 5 Tactical Pistol Buffer Tube (PBT)
If you’re looking for a high-quality AR-15 pistol buffer tube that combines billet aluminum strength, Mil-Spec dimensions, Type III hardcoat anodizing, and an included foam cheek rest with end plate and castle nut, the Phase 5 Tactical Pistol Buffer Tube PBT (UPC 813318020406) is an outstanding choice. It’s a small part that makes a big difference in the reliability, comfort, and overall quality of your AR pistol build.
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