Magpul PMAG M3 AR-15 300 Blackout Polymer Magazine - 30 Round Capacity

The Magpul PMAG M3 AR-15 300 Blackout polymer magazine is purpose-built for shooters running 300 BLK in their AR platform rifles. If you've been feeding your 300 Blackout rifle with standard 5.56 NATO magazines, you know the compromise: variable reliability with heavier, wider bullets, and the constant risk of dangerous cross-loading ammunition. This 30-round magazine solves both problems with a dedicated design that respects the unique geometry of 300 Blackout ammunition while giving you the confidence that comes from using the right tool for the job.

The safety angle here matters. Magpul engineered a visually and tactilely distinct magazine—featuring a unique rib pattern and smoother upper texture—so there's zero confusion on the firing line or in your gear bag. You'll instantly know this is a 300 Blackout magazine, not a 5.56 mag. That distinction eliminates the risk of accidentally chambering a 300 BLK round in a standard rifle, which could result in a dangerous over-pressure situation. It's the kind of thoughtful design that keeps you and your rifle intact.

Like all Gen M3 PMAGs, this magazine is built from Magpul's next-generation impact and crush-resistant polymer with aggressive front and rear texturing for solid control. The removable slim floor plate makes cleaning and inspection straightforward, and the paint pen dot matrix on the body lets you mark and identify your mags at a glance. At 5 ounces and 7.5 inches in length, it fits standard AR lowers and works across most STANAG 4179-pattern platforms, including AR-15, M4, FN SCAR, and IWI Tavor rifles. Made in the USA.

Key Features

• Purpose-designed for 300 Blackout ammunition geometry and performance
• Distinct rib pattern and smooth upper-half texture prevent dangerous cross-loading with 5.56 magazines
• Gen M3 impact and crush-resistant polymer with aggressive texture
• Removable slim floor plate for easy cleaning and maintenance
• Paint pen dot matrix for marking and identification
• Fits AR-15, M4, M16, and other STANAG 4179-compatible platforms
• Made in the USA

Specifications

Frequently Asked Questions

Will this 300 Blackout magazine work in my AR-15?

Yes. The PMAG M3 is designed for AR-15 and M4 platform rifles chambered in 300 Blackout, as well as other STANAG 4179-pattern rifles including FN SCAR and IWI Tavor. It will not fit rifles chambered in 5.56 NATO or other calibers—it is caliber-specific.

Can I use 5.56 NATO magazines for 300 Blackout ammunition?

While 5.56 magazines may physically load some 300 Blackout ammunition, this magazine was purpose-built to avoid the reliability issues and safety risks that come with that approach. The distinct design and differentiation from standard PMAGs means you'll always know which magazine you're grabbing, eliminating the risk of cross-loading ammunition into the wrong rifle.

Does this magazine come with a dust cover?

No. The magazine does not include a dust cover, but the removable slim floor plate makes the magazine easy to clean and inspect.

What is the paint pen dot matrix for?

The paint pen dot matrix printed on the magazine body allows you to mark and identify your magazines. Use a paint pen to write load dates, ammunition type, or any other information you want to track on that specific magazine.