PMAG Generations Explained: Gen M2 vs Gen M3, 20 vs 30 vs 40 Round (Live Prices)

Short answer: buy the PMAG 30 Gen M3. It weighs 5 oz and, per Magpul, fits most STANAG rifles, including the HK416, SA-80 and SCAR MK16. The cheaper Gen M2 MOE is the same size and weight but is made for Colt-spec AR-15s only; Magpul says it does not fit an SA-80 or HK416. Pick capacity by use: the PMAG 20 (5.6 in) sits low for prone shooting and benches, the PMAG 30 (7.5 in) is the standard, and the PMAG 40 (9.7 in) is for range days. For 300 Blackout use the dedicated PMAG 30 AR 300 B.

PMAG generations and sizes

Specs are from Magpul's PMAG 30 GEN M3, GEN M2 MOE Window, PMAG 40 and PMAG 30 AR 300 B pages, read October 2026.

Gen M3 vs Gen M2 MOE

Both are 30-round, 7.5 inch, 5 oz polymer magazines with an anti-tilt follower. The difference is fit and features:

• Compatibility. Magpul says the GEN M3 fits most STANAG 4179 platforms and names the AR-15/M4, HK416, SA-80, SCAR MK16, M27 IAR and IWI Tavor. The GEN M2 MOE is "optimized" for Colt-spec AR-15/M4 rifles and is "not compatible with SA80 and HK416, or similar, platforms".
• Features. The GEN M3 adds a paint-pen dot matrix for marking loads, an over-insertion stop and a removable slim floorplate. Magpul's tagline for the GEN M2 MOE is "PMAG reliability, MOE simplicity".
• Windows. Both come with or without see-through windows that show roughly how many rounds are left.

On a standard AR-15, either works. If you also shoot an HK416-pattern rifle, a SCAR or a Tavor, buy GEN M3.

20 vs 30 vs 40 round PMAGs

• PMAG 20 (5.6 in, 4 oz): sits lower under the rifle, which helps prone and on a bench.
• PMAG 30 (7.5 in, 5 oz): the standard size that fits most pouches; Magpul says its slim floorplate suits many double and triple pouches.
• PMAG 40 (9.7 in, 6.6 oz): fewer reloads, but longer and heavier.

Some states limit magazines to 10 rounds; see our California, New York and New Jersey guide. Magpul's PMAG 10/30 is a 10-round magazine in a 30-round body. Magpul notes it cannot ship to jurisdictions that restrict magazine sales.

PMAG 30s, with today's prices

Lowest price across the stores we track:

PMAG 20, 40, 300 Blackout and 10-round, with today's prices

Accessories and care

Magpul sells impact and dust covers for both generations, and its MagLink coupler joins two GEN M3 or GEN M2 MOE PMAG 30s or 40s. Want a colored magazine? See how to dye PMAGs. For 300 Blackout parts, see 300 Blackout BCG and magazines.

Compare every AR-15 magazine by price, and plan the build in the AR-15 builder.

Comparing PMAGs with other brands? See the best AR-15 magazines, including Lancer and Daniel Defense.

Frequently asked questions

What is the difference between PMAG Gen M2 and Gen M3?

Same 30-round size and 5 oz weight, but Magpul says the GEN M3 fits most STANAG rifles including the HK416, SA-80 and SCAR, while the GEN M2 MOE is made for Colt-spec AR-15s and does not fit an SA-80 or HK416. The GEN M3 also adds a paint-pen dot matrix and over-insertion stop.

Do Gen M3 PMAGs work in an HK416?

Yes. Magpul lists the HK416 among the GEN M3's compatible platforms.

Which PMAG is best for an AR-15?

The PMAG 30 AR/M4 GEN M3 for most rifles; the GEN M2 MOE is fine and cheaper if you only own Colt-spec AR-15s.

How long is a PMAG 30?

7.5 inches maximum, per Magpul. A PMAG 20 is 5.6 inches and a PMAG 40 is 9.7 inches.

Can I use 5.56 PMAGs for 300 Blackout?

Magpul makes a dedicated PMAG 30 AR 300 B that it says feeds 300 Blackout more consistently and is marked by a rib and texture so you do not mix it up with 5.56 mags.

How much does a PMAG weigh?

Magpul lists the PMAG 30 GEN M3 and GEN M2 MOE at 5 oz, the PMAG 20 at 4 oz and the PMAG 40 at 6.6 oz, empty.