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MAGPUL PMAG M3 AR-15 MAGAZINE - 300 BLK - 10 ROUND CAPACITY - 20 ROUND BODY - BLACK
Magpul Industries
$20.99 - $21.69
(2 reviews)
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Magpul Industries
MAGPUL PMAG M3 AR-15 MAGAZINE - 300 BLK - 10 ROUND CAPACITY - 20 ROUND BODY - BLACK
The Magpul PMAG M3 AR-15 Magazine in 300 Blackout is a purpose-built, California-compliant 10-round magazine housed in a full-size 20-round body — engineered specifically for the 300 BLK cartridge rather than adapted from a 5.56 design.
- Permanently blocked to 10 rounds via proprietary block and rivet for compliance
- Designed from the ground up for 300 Blackout cartridge geometry and feeding
- 20-round body profile offers comfortable grip and familiar handling ergonomics
- GEN M3 construction features impact-resistant polymer and anti-tilt follower
- Compatible with standard AR-15 lower receivers and mag wells
- Includes dust/impact cover and stainless steel spring for long-term reliability
Who This Is For
This magazine is the ideal choice for California-based 300 Blackout shooters who want a reliable, dedicated mag that feeds their preferred cartridge flawlessly — without the feeding compromises that come from repurposing a 5.56 magazine. Whether you're running a suppressed SBR-style build or a full-length 300 BLK carbine, this PMAG delivers consistent performance while keeping you on the right side of California's magazine capacity laws.
Specifications
| Brand | Magpul Industries |
|---|---|
| Model | PMAG 30 AR 300 B GEN M3 |
| Caliber | 300 Blackout (.300 BLK) |
| Capacity | 10 Rounds (California Blocked) |
| Body Size | 20-Round Profile |
| Color | Black |
| Material | Impact-Resistant Polymer |
| Spring | Stainless Steel |
| Compatibility | AR-15 Standard Magazine Well |
| Compliance | California Restricted States Legal |
| Includes | Dust/Impact Cover |
Frequently Asked Questions
Why is this magazine specifically designed for 300 Blackout instead of using a standard 5.56 PMAG?
The 300 Blackout cartridge — particularly when loaded with heavy subsonic projectiles — has a wider variety of bullet weights and ogive profiles than 5.56. Using a magazine designed for 5.56 introduces potential feeding inconsistencies with these loads. Magpul engineered the PMAG 30 AR 300 B from the ground up with geometry optimized for the full spectrum of 300 BLK ammunition, from lightweight supersonic rounds to heavy 220gr subsonic loads, ensuring more reliable feeding across the board.
Is the 10-round block permanent, and can it be removed?
Yes — the capacity block in this magazine is permanently installed using a proprietary block and rivet, making it irreversible under normal circumstances. This permanent modification is what makes the magazine legal for sale and use in California and other states with magazine capacity restrictions. Attempting to remove or defeat the block would be illegal in California and would void any product warranty.
Will this magazine work in any AR-15 lower receiver chambered in 300 Blackout?
Yes. The PMAG M3 300 BLK is designed to fit standard AR-15 STANAG-compatible magazine wells, which is the most common lower receiver pattern used in 300 Blackout builds. It is compatible with the vast majority of mil-spec and commercial AR-15 lowers. As always, Magpul recommends verifying compatibility with your specific firearm, particularly if you are running a non-standard or aftermarket lower receiver.
- Capacity:
- 10/20 Round
- Caliber:
- 300 BLK
- Color:
- Black
- Follower Color:
- Black
- Type:
- Magazine
- CA Compliant:
- Yes
- Platform:
- AR-15
- Material:
- Polymer
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Reviews
-
Nicely riveted
Nicely done block and riveting. Will definitely purchase more.
-
10/20
Seems super sturdy. I loaded one mag very easily. I never use loading assist and it was very quick . Can’t wait to get to the range. Truly, going to .300 blackout from .223 my only issue has been mag pressure. Gotta love the 10/20… unfortunately New Jersey only allows for ten rd mags. These are the way to go.