Magpul PMAG M3 20 Round Magazine – .300 BLK – MAG1182


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Highly Reliable 20-Round Magazine Designed Specifically for 300 BLK Rifles

The Magpul PMAG M3 20 Round – MAG1182 is a dedicated and highly reliable polymer magazine designed specifically for rifles chambered in .300 AAC Blackout (300 BLK). This PMAG is more compact for increased maneuverability and creates a more concealable package for use in small format firearms.

300 BLK in the past has been known for its compatibility with 5.56x45mm magazines.  However, many subsonic loads with longer projectiles can have feeding issues with traditional 5.56 magazines and this magazine solves that issue, providing shooters a true .30 caliber AR magazine that functions under the constraints of the existing AR-pattern dimensions.

Incorporates The Features & Performance of the GEN M3 Magazines

The Magpul PMAG M3 20 Round offers a safer, more reliable way to feed a 300 BLK rifle with a distinct ribbed design and smoother upper-half texture that provides the shooter a distinct visual and tactile difference from any other PMAG to mitigate dangerous cross-loading issues.

Along with its optimized 300 BLK performance, the PMAG 20 incorporates all of the GEN M3 features, including the next-generation impact and crush resistant polymer, aggressive front and rear texture, an easily removable slim floor plate, a paint pen dot matrix for marking and identification, and a dust/impact cover.


  • Purpose Built Magazine Only for .300 BLK
  • Designed With Visual and Tactical Differences
  • Incorporates The Same Features And Performance Of the Gen M3 Line
  • Constant-Curve Geometry
  • Long Life Stainless Steel Spring
  • Ribbed Gripping Surface
  • Aggressive Front/Rear Texture
  • Paint Pen Dot Matrix Panel on Lower Label
  • Made in the USA


  • Caliber: 300 BLK
  • Platform: AR15, M4, M16Caliber: .300 AAC Blackout
  • Capacity: 20 Rounds

Have Questions About this Product?

The AT3 Tactical store has a 90 day no-hassle return policy for products in good condition. You can view the full details of our return policy here.

If you encounter an issue or defect with a product after 90 days of your purchase, you can refer to the manufacturer for a warranty claim. Their policies are below.

Magpul Warranty Information

If you ever experience an issue with a Magpul product at any time, regardless of where it was purchased, please contact us directly and we’ll do everything reasonable to help you.

To make a return, please take the following steps:

  • BEFORE returning any products, please contact us first to receive an RMA number (Return Merchandise Authorization) and prominently write it on the outside of the package. Packages will not be accepted without an RMA.
  • Include a note with your name, shipping address, phone number and email, RMA number, and reason for the return (including, if applicable, information about the firearm, ammunition, and usage environment for defective returns). Do not send ammunition.
  • Wrap the item with quality padding and place it in the original packaging or in an appropriate box for shipping.
  • A UPS shipping label will be provided in your shipment. If using the original packaging, remove or cover the original shipping label. Tape the preprinted return shipping label to the outside of the box. Drop package at an official or authorized UPS drop-off location.
  • All refunds will be applied to the credit card used for the original purchase. You should allow one to two billing cycles for the refund to appear on your statement.

Disclaimer: Manufacturer’s warranty is subject to change without prior notice.

Customer Reviews

Based on 7 reviews

No problems. My rifle likes them.

Thank you for the positive feedback! We are glad to hear that our product is working well for you and your rifle. Happy shooting!

Magpul magazines are always my gold standard

I have three 300BLK units all setup for different purposes. Two of these have PSA branded lower receivers and one has a Black Rain lower receiver. Using Magpul 556 magazines and cartridges with 300BLK 110 gr. V-MAX and 110 gr. TAC-TX bullets, all mags insert into all receivers and work okay, with the Black Rain receiver having more resistance than the PSA.

However, my cartridges using the Maker 200 gr. bullets noticeably drag inside the magazine well of the PSAs but still work, while the Black Rain magazine well is apparently smaller inside and makes the Magpul 556 magazines unusable with this bullet profile.

These Magpul 300BLK specific mags all work well with all bullet types in both receiver brands.

Thanks for sharing your feedback! We're glad you're satisfied with your purchase.

Don G
Perfect 300 Blk mag

Flawless, feeding locks up and drops free just what you need in a magazine

Thanks for sharing your feedback! We're glad you're satisfied with your purchase.

Tim Graham
Look good

They look good and seem to feed a little better

Thanks for sharing your feedback! We're glad you're satisfied with your purchase.

Jamie Philpott

Great product, works awesome 👍

Thanks for sharing your feedback! We're glad you're satisfied with your purchase.