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Q&A for Magpul Industries PMAG GEN M3 AR-15 .300 Blackout 20 Round Rifle Magazine — 1 Questions & 1 Answers

Name Magpul Industries PMAG GEN M3 AR-15 .300 Blackout 20 Round Rifle Magazine (4.9)
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Rat, guest, from WV, United States, asked on November 26, 2024

I've been told that .300 B/o ammo can loaded in a .223/5.56 magazine, and it will feed. Can I load these .300 Blackout mags with .223/5.56 ammo?

A
Answered by myco, member, from OH, United States, on October 03, 2025

I came to ask same question as I ordered 2 incorrectly I guess. I did search online and it suggests no, that the 300 blk mags were designed with slightly wider feeds to accommodate the fatter rounds and may lead to loose feed of 223/5.56 rounds, they emphasized it is an issue of safety, implying potential catastrophic failure vs. ftf . currently that is only info I could find, however it was not specific info from pmag, so I will not say it is factual, though it seems logical. I will return mine out of caution. but I encourage you to wait for authoritative answer rather than relying on my internet searches, lol. cheers mate, good luck.

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