Magazines for 300 blackout

[thelaststand]

I found that 300 blackout had a problem with the follower guides on the inside of the magazine body especially if you load a thick caste lead bullet. The bullets are pushed against the guide and create friction so if you load more than 10 rounds the magazine doesn't function like it is supposed to.

Has anyone tried modifying mags?

I tried using a chisel and removed the guides from the inside of the mag and now they cycle like normal.

 

[cfullgraf]

Many bullets cannot be loaded to magazine length with the 300 BLK because of the front guide in the magazine.

The bullets need to be loaded deep enough so that guide does not cause problems.

I have loaded 200 plus grain cast bullets, the one Missouri Bullets sell, for my 300 BLK that functioned fine from tha magazine. I had other issues but not feeding issues.

Look at Wilson Combat and their 7.62x40 NT cartridge. This is similar to the 300 BLK. They sell a modified magazine and talk about modifying magazines.

 

[CLP]

I've never had a problem loading/shooting 30rds in Brownell's mags. However, I mostly only shoot 125 SMK's. You don't have any problems with cycling while using cast bullets? Suppressor? What mould? Thanks.

 

[thelaststand]

I had problems with 170 grain lead cast round nose in pmags. The sides of the bullets would rub against the guide inside the mag. I used a chisel to remove the guide and the problem went away and the mags cycled without any problems. I was wondering if anyone else has done this and their results.

 

[cfullgraf]

I used a chisel to remove the guide and the problem went away and the mags cycled without any problems. I was wondering if anyone else has done this and their results.

Nope, I have not needed to modify any magazines i use with 300 BLK.

 

[Mr.Revolverguy]

There are plenty of reports of modifying mags on 300blktalk.com but I wouldn't do it and you should not need to.

Cproduct Defense has works flawlessly for me with cast lead the 245gr from MBC to be exact.
https://www.cpdmags.com/Products.html

Troy industries battlemags has been flawless for me also with the same bullets.
https://troyind.com/plastics/magazines

To get good accuracy out of MBC lead make sure you get a Lee Universal Rifle expander die to flare the case mouth to keep from shaving brass.

PMAGS have been so-so for me with 300blkout. To be able to quickly tell the difference I just ordered the metal mags from Cproduct Defense for all 300 work. 223 Work is all plastic.

 

[Paddy]

I have at least 6 brands of mags and they pretty much all have issues with the 300blk. This is the big caveat to the whole concept of the cartridge. My best operating mag for it is actually my crappiest mag. It's a thermold mag it looks like junk but it runs like butter.

 

[Wil Terry]

I used toi work foir the original manafacturer of 300WHISPER ammunition and I NEVER EVER NEVER had to modify ANY of my AR15/M16 magazines [ 100?? ] to feed J.D.'s masterfully designed cartridge. NEVER!!
And so it goes...

 

[thelaststand]

I use a lot of liquid alox lub on the lead bullets which creates a lot of friction against the guide, purhaps that is the problem. The FMJ loads work fine in the pmag. My Lancer mag works well unmodified with the sticky lead bullets.