.450 Bushmaster magazines

[Little Dutch]

It appears that these are AR-15 magazines with a new follower. Can anyone confirm that? Or do I need a special magazine?
If it's literally just a different follower I have some 10 rounders I can convert over. http://www.chambertactical.com/

Thanks,
Brett

[Gunner]

Pretty sure it’s the same mag. But I could be wrong


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[TFOGGER]

That is correct

10=5
20=9
30=13

[ben4372]

Yep. And a guy makes a pop in follower that works great. You just "roll" it in from the top. I bought a few of these when I first got my 450. Its funny, the factory built .450 mags have a dimple or crimp to keep you from pulling the follower and dropping in a .556. These are the ones I bought, I think. https://www.ebay.com/itm/Magazine-Follower-for-450-Bushmaster-Caliber-/152137172696

Almost forgot. I had to cut a crescent relief in the front of the mag, similar to factory ones.

[Little Dutch]

Thanks for the replies, it helped immensely.

That single-shot follower ben linked is similar to what I was looking at, but that guy has marketed his to the .450, so we know it works, and he's a few dollars cheaper on shipping than what I was looking at. That seems like the way to do it. Jut order 3 or 4 and forget about factory magazines until I stumble across a deal at a gunshow.

Cutting a crescent relief in the front of the magazine, is that necessary for feeding, or more for ease of unloading? I ask because my 7.62x39 magazines are a hassle to unload, but still feed correctly.

Thanks

[MarkCO]

Thanks for the replies, it helped immensely.

That single-shot follower ben linked is similar to what I was looking at, but that guy has marketed his to the .450, so we know it works, and he's a few dollars cheaper on shipping than what I was looking at. That seems like the way to do it. Jut order 3 or 4 and forget about factory magazines until I stumble across a deal at a gunshow.

Cutting a crescent relief in the front of the magazine, is that necessary for feeding, or more for ease of unloading? I ask because my 7.62x39 magazines are a hassle to unload, but still feed correctly.

Thanks

I have both the single shot followers (I paid like $5 a piece) and 10 of the actual DPMS black followers I got from Tim LeGendre directly. Also a PVC pipe section follower I made for a PMag and one for a Lancer Mag. A section of pipe, sandpaper, a few screws and epoxy and you can make your own for less than a dollar. Other than follower, nothing else needed for mags.

[Little Dutch]

Thanks Mark. I Appreciate the info.

[Little Dutch]

Yep. And a guy makes a pop in follower that works great. You just "roll" it in from the top. I bought a few of these when I first got my 450. Its funny, the factory built .450 mags have a dimple or crimp to keep you from pulling the follower and dropping in a .556. These are the ones I bought, I think. https://www.ebay.com/itm/Magazine-Follower-for-450-Bushmaster-Caliber-/152137172696

Almost forgot. I had to cut a crescent relief in the front of the mag, similar to factory ones.

The followers work well in 20 round metal mags. I didn't cut a relief on them, but did have to gently squeeze the lips together.
I have found that the Hornady Black factory cartridges are actually too long to make the curve in the 30 round steel magazines. I haven't gotten any of my P-Mag magazines to work. They would require some extensive material removal to make work.

[Little Dutch]

Revisiting this as I've finally found a workable solution.

I was never satisfied with the metal magazines. The Bushmaster magazines fit the best (go figure), but any metal magazine I tried didn't really want to retain more than 4 or 5 rounds very effectively. The cases are just a little too small in diameter, and the magazine lips are just not tight enough. If you load up a magazine and smack it with your palm you'll lose a cartridge most of the time.

I tried a plastic magazine, some brand that wasn't Magpul. It had the same problem, the lips didn't have enough tension to retain more than 3 or 4 rounds.

My solution was found with 20 round PMags. Inside of the PMag is a little rib of plastic that acts as a follower guide and stop. The cartridges are slightly too long to fit into the PMag's because the tip of the bullet won't clear that rib in front of the follower. I found a file that fit into the magazine and started working that follower guide-rib down. I kept at it until it was completely gone. After reassembling the magazine I was pleased to find that it effectively held 8 .450 Bushmaster cartridges. However, it works better with 7. When fully loaded with 8, the drag on the bolt is too much to reliably chamber the second round after firing the first.

I trimmed one of those single shot followers to fit the PMag magazine. It works well otherwise, but it doesn't come up high enough to trigger the last round hold open. I like the last round hold open, so I took the single shot follower back out.

I have not attempted to trim a 30 PMag to a 13 round .450 Bush Master magazine yet. But I know 20's work pretty good when you convert them to 7's.