Update, October 9, 2026: ATF no longer requires a Form 4, tax stamp, fingerprints or registration for suppressors, short-barreled rifles, short-barreled shotguns or AOWs. They now transfer on a standard Form 4473 with a background check. Anything below that mentions a Form 4, a wait or a tax stamp was written before this change. What changed
⚠ SUPPRESSOR — NO FORM 4 REQUIRED Since October 9, 2026, ATF no longer requires a Form 4, tax stamp, fingerprints, photos or registration for suppressors. It transfers like any other firearm: a Form 4473 and a NICS background check. Buyer must be 21 or older and allowed to own a suppressor under their state’s law. Outside Texas, we ship to an SOT dealer in your state. What changed · How buying one works now
Maxim Defense Ruger Mark IV Integrally Suppressed .22 LR Pistol
The Maxim Defense MKIV-SD is an integrally suppressed Ruger Mark IV .22 LR pistol with Maxim’s M-Kore™ Technology. Inspired by the legendary HK MP5SD, the MKIV-SD’s ported barrel and diffuser reduce supersonic ammunition to subsonic speeds — averaging 114 dB with subsonic loads and 123 dB with standard velocity. No first-round pop. Total length: 12.6". 5.95" barrel. 7" x 1" suppressor tube (4130 steel). 3-piece user-serviceable design with carbon cutters. 10-round capacity. Optic-ready. Made in USA.
Spec
Detail
Caliber
.22 LR
Barrel Length
5.95"
Total Length with Suppressor
12.6"
Suppressor Tube
7" x 1.0" diameter — 4130 steel
Sound Level
114 dB avg (subsonic) / 123 dB (CCI Minimag) — MIL-STD-1474D
The Maxim Defense MKIV-SD is one of the quietest semi-automatic pistols commercially available — 114 dB average with Gemtech subsonic ammunition puts it below the threshold of pain. The MP5SD-inspired design ports propellant gas from the barrel into the suppressor body, actively slowing supersonic ammunition to subsonic speeds. At 12.6" total length, the MKIV-SD is virtually no longer than a standard Ruger Mk IV.
Maxim Defense Industries is a Minnesota-based American firearm manufacturer and ISO 9001:2015 certified company. The PDX and SDX platforms were developed directly from the SOCOM PDW solicitation — designed to meet the demands of Tier 1 operators who need maximum lethality in a minimum package. Maxim Defense builds its firearms from military-grade materials: 6Al-4V titanium, 17-4 stainless steel, 7075-T6 and 6061 aluminum. Every firearm is built to order in the USA.
Frequently Asked Questions
What NFA process is required? BATFE Form 4 transfer, background check, $200 tax stamp now $0 under OBBBA. Allow 30–90 days for ATF approval.
What mount does the Maxim suppressor use? Maxim Defense suppressors use the proprietary HUB Mount system — a quick-attach interface requiring a compatible HUB muzzle device on the host.
Are Maxim Defense suppressors full-auto rated? Yes — Maxim Defense suppressors are built from military-grade materials and tested to SOCOM standards.
We file your Form 4 for you. No Form 4 needed.
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.
This item is out of stock. These are on the shelf today and ship or transfer the same way. Not sure which is the right swap? Call 817-393-4000 and we will tell you straight.
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