Description
The CMMG MK4 PDW .300 AAC Blackout 8.2″ Barrel, RKM7 KeyMod Free-Float Hand Guard, 30 Rd Mag- All NFA Rules Apply is a compact, high-performance pistol-caliber carbine designed for close-quarters use. It’s a factory-built firearm chambered in the versatile .300 AAC Blackout round, featuring a short 8.2-inch barrel and a KeyMod free-float handguard for a lightweight, customizable platform. This item is regulated under the National Firearms Act (NFA), meaning it requires specific federal registration, tax stamp approval, and compliance with state laws before transfer. It ships to Missouri and compliant US states.
Key Features
- Optimized .300 BLK Platform: The 8.2″ barrel is the ideal length for the .300 AAC Blackout cartridge, ensuring proper powder burn and maximizing ballistic performance with both supersonic and subsonic ammunition.
- RKM7 KeyMod Hand Guard: A lightweight, free-float handguard with KeyMod attachment points for mounting lights, lasers, grips, and other accessories without adding significant bulk or weight.
- PDW (Personal Defense Weapon) Configuration: The compact overall size makes it highly maneuverable in tight spaces, a practical choice for home defense or as a truck/ranch gun.
- Complete & Ready: Comes with a 30-round magazine and is built on CMMG’s reliable MK4 platform. It’s drop-in ready for your NFA trust paperwork and FFL transfer.
- Budget-Conscious Performance: At $936.98, this factory-built CMMG offers a significant value compared to piecing together a similar-quality NFA item from individual parts, saving you time and potential gunsmithing costs.
Specifications & Details
| Caliber | .300 AAC Blackout |
| Barrel Length | 8.2 inches |
| Handguard | RKM7 KeyMod Free-Float |
| Magazine | 30-Round Included |
| Action | Direct Impingement Semi-Automatic |
| Lower Receiver | Mil-Spec AR-15 Pattern |
Weighing in at just over 6 pounds unloaded, this PDW balances heft for stability with a size that’s easy to handle. The mil-spec lower receiver is a huge plus—it means broad compatibility with a vast aftermarket of AR-15 triggers, grips, and stocks (once properly registered as an SBR). You can use common parts from brands like Magpul or BCM for customization. Here’s the thing—while the initial price is a factor, don’t forget the added $200 tax stamp and potential trust fees when budgeting for this NFA item.
Who This Firearm Is For
This CMMG MK4 PDW is for the shooter who understands the NFA process and wants a compact, hard-hitting package without the hassle of a custom build. It’s ideal for Missouri residents looking for a potent home defense tool that’s more capable than a pistol but shorter than a full-length rifle. It’s also a solid choice for recreational shooters who appreciate the .300 BLK round’s flexibility—quiet with subs at the range, powerful with supers for hunting medium game within its effective range. Given its 8.2-inch barrel, this firearm is designed to be most effective inside 200 yards.
Practical Pros & Cons
Pros: You get a complete, quality-built CMMG firearm for under $1,000, which is notable for an NFA-eligible item. The .300 BLK caliber from a short barrel makes real sense, unlike trying to shoot 5.56 from an 8-inch tube. The KeyMod rail, while some prefer M-LOK, is still widely supported with affordable attachment options. Since it’s mil-spec compatible, upgrades are straightforward and don’t require a gunsmith.
Cons: The obvious one is the NFA paperwork, wait time, and extra $200 tax. KeyMod is a slightly older attachment system, though perfectly functional. Ammunition for .300 AAC Blackout is more expensive than 5.56x45mm NATO, so practice costs are higher. You’re trading long-range capability for compactness—that’s the core tradeoff.
Frequently Asked Questions
Q: What does “All NFA Rules Apply” mean for me as a buyer?
A: It means this firearm is regulated under the National Firearms Act, typically because its barrel length is under 16″ and it’s configured as a “pistol” or requires registration as a Short-Barreled Rifle (SBR). You must complete ATF Form 4, pay a $200 tax stamp, and receive approval before taking possession. An FFL transfer required for firearm purchases, especially NFA items, is a strict process we help facilitate.
Q: Is this ready to shoot, or do I need to buy anything else?
A: It is functionally complete and includes one 30-round magazine. You will need .300 AAC Blackout ammunition and, if desired, an optic or iron sights. The upper and lower are assembled, so no gunsmithing is required. Just remember, you cannot legally take it home until your NFA paperwork is approved by the ATF.
Q: Can I put a stock on this, or is it a brace?
A: The product’s configuration can change based on current ATF rulings. As of its last update, it may be sold with an arm brace or as a pistol. If you wish to attach a traditional stock, you must first register it as an SBR on a Form 1 or Form 4. We recommend consulting with us at the time of purchase to ensure you understand the compliant configuration and your intended use.
For a capable, compact .300 BLK platform that delivers CMMG’s reliability at a value-focused price point, this MK4 PDW is a practical option. Explore the details and start your compliant purchase process at firearms-missouri.com.
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