Description
The Maxim Defense PDX-SD is an ultra-compact pistol on Maxim's PDX platform. This one is chambered in 300 Blackout, with Maxim's CQB stock system and a 5/8×24 threaded muzzle, in black.
300 Blackout was designed around short barrels and suppressor use. Its powder charge is small and burns quickly, so a barrel this short gives up far less velocity than the same length would in 5.56, and the cartridge is loaded both supersonic and subsonic – the subsonic loads being the ones intended for suppressed shooting.
The SD designation is about what it is built to run. Maxim make a dedicated DSX suppressor for the PDX – shorter and larger in diameter than a conventional can, with no barrel-length restriction, integrated carbon cutters, and user-serviceable with common tools. Maxim describe it as reducing gas blowback and holding the cyclic rate down compared with a conventional suppressor on the same host.
THE SUPPRESSOR IS SOLD SEPARATELY. This listing is the firearm with a threaded muzzle. A suppressor is an NFA item in its own right: it transfers on an ATF Form 4 with fingerprints, a photograph and an ATF background check, and you cannot take possession until that is approved. Since 1 January 2026 the transfer tax on suppressors is $0, but the registration and approval are unchanged, so plan for the wait if you intend to run it suppressed.
Configured as a pistol, it stays a pistol. Fitting an actual shoulder stock to a firearm with a barrel under 16 inches makes it a short-barreled rifle – an NFA item that must be registered and approved before it is assembled, not after. If you are unsure what you have, ask us first.
This is a serialized firearm. It ships to a licensed dealer near you rather than to your door, and you complete the transfer there with a Form 4473 and a background check. State and local rules govern what can be shipped where, so check yours before ordering – and if you are unsure, ask us first.
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