Radical Defense MK1 Mod 1.5, PDW, SBR, 5.56 NATO, 6.5″ Barrel, Black, 30 Rounds

The Radical Firearms PDW SBR takes the 5.56 AR-15 platform to its most compact configuration — a 6.5-inch barrel that puts this firmly in Personal Defense Weapon territory. The 6.5-inch barrel is shorter than even a standard MK18 (10.3″) or a typical SBR lower (7.5–10.5″), placing it in the PDW class where portability is the entire point. At this barrel length, 5.56 NATO velocity is significantly reduced — muzzle velocity will be in the 1,800–2,100 fps range with M855, versus the 3,000+ fps of a 20-inch service rifle. The tradeoff is a platform that folds, carries, and deploys in extremely confined spaces.

Radical Firearms, based in Houston, Texas, builds AR-platform firearms at a price point that makes NFA ownership more accessible. The PDW SBR at $1,999 is positioned as a working-class SBR — the paperwork cost is the same whether the lower receiver is a $400 Radical or a $2,500 Daniel Defense, but the total investment is substantially different. For buyers who want a short-barrel SBR configuration for practical use without the premium-tier price, Radical Firearms is the answer.

Radical PDW SBR 5.56 Specifications

Ordering from Western Sport

Order online and we ship it to the licensed FFL dealer you choose near you — see how buying a gun online works. Western Sport has been a licensed FFL/SOT dealer since 2007, and everything we sell carries the full manufacturer warranty. Questions before you order? Send us a message.

FAQ — Radical PDW SBR 5.56

Is 5.56 from a 6.5″ barrel effective?

At 6.5 inches, 5.56 NATO velocity drops significantly versus longer barrels. However, the PDW SBR is optimized for close-range (0–100 yards) scenarios where a compact platform is more important than maximum velocity. Modern 5.56 defensive loads maintain terminal effectiveness at reduced velocities. This platform is most suitable for confined-space use, vehicle work, or any scenario where a full-length or standard-SBR-length AR is impractical.

Is this suppressor-compatible?

Yes — with a muzzle device adaptor or the appropriate suppressor for the barrel’s thread pitch. The 6.5″ barrel will be significantly over-gassed when suppressed versus a longer barrel; an adjustable gas block is recommended for extended suppressed use.

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