What's the story behind the 25 round straight AR mags?

[TTv2]

I'm a big fan of the straight AR magazines, I feel that they're a lot less cumbersome to carry, easier to shoot prone, and maneuver the gun with. Twenty rounds is a good amount, but why settle for less when in the past 25 round mags were the original magazines that were planned to be used in the vintage Armalite rifles?

So what's the deal with these vintage 25 round magazines? Why were they ditched for 20 round and 30 round magazines? Is there any chance that the 25 rounders will make a comeback outside of some asinine future law that outlaws magazines with capacities of 30 rounds or more?

 

[dbmjr1]

The tapered cartridge requires a curve after 20 rounds. They didn't work and were recalled almost as fast as they were issued.

 

[TTv2]

So if the cartridge was straight walled, the 25 round mags, with appropriate follower, could be used with something like .450 Bushmaster or .50 Beowulf?

 

[Riomouse911]

Makes sense, with the straight cased rounds it should work like a giant .45 1911 Mag.

 

[Dan Forrester]

I don’t think straight walled cases feed as well in semi autos. A triangle shaped case like 7.62x39 will be more forgiving when loading into a dirty chamber.

Dan

 

[zaitcev]

It's not like making a straight 30-rounder for 5.56 is magic. You know how they make straight rimfire magazines, right? The cartridges are twisted in a zig-zag pattern, so that the fronts lay on each other like in a straight magazine, and the case bottoms are staggered. The taper on 5.56 is small enough that you don't even have to cross the bullets completely. Piece of cake.

However, this only works well with a single-feed gun, like MP-38/40. The feed system on M4 is set for double-feed. I suppose you could feed guns like CETME-L or the original M16. And unfortunately, there's another problem: charging these zig-zag twist straight magazines from the top is next to impossible.

It's much easier to have magazines that can be charged from clips and require wider pockets on your vest than magazines that are straight and cannot be charged.