Why do people talk about modifying magazines for the 300 AAC BLK?

[mannythegreek]

Hey all,

I was checking out different websites regarding the 300 blackout and I found that alot of people talk about modifying their magazines- essentially removing the "rib" of the PMAG or Lancer Advanced Warfighter Magazine.

Im kind of surprised. I was under the impression that this round would feed normally with unmodified mags. Why is the removal of the rib needed? Still others talk about filing it down. Others say that this was a problem but now the round is standardized for GI magazines.

Thanks!

-MannytheGreek

[Quiet Riot]

Neither necessary nor recommended for factory ammo. In fact, the new 300 BLK bullets depend upon the standard rib to maintain cartridge alignment in the magazine.

For reloads using long, fat bullets designed for the .308, the rib can tip the cartridge inward and cause feeding problems. So, in some cases, it can be beneficial to modify one or a few mags for using these reloads.

[J Krammes]

The original prototype rounds did not fit properly and the mags had to be modified. You DO NOT have to modify any mags with the factory ammo currently available. I have a 30 round P-Mag full of Rem. 220 gr subs that fit and feed just fine on my safe right meow...

Jk

[GunnutAF]

Agreed, one only has to be aware of your COAL when reloading to ensure your Alcove doesn't cause the cartridges are not tilted inwards. :D

[rsilvers]

2010 called and they want their ammo back.

300 AAC Blackout ammo is optimal for standard magazines.

That was more of a 300-221/Fireball/Whisper(R) issue before the current 300 AAC Blackout ammo was shipping. This, the SAAMI standard, and supersonic/subsonic that works without an adjustable gas system are the primary things that 300 BLK brought to the table that were not a given in the past.