Great pictures as usual, Johnwill.
A bit of history might help. Originally, the idea was to issue carbine ammo in loaded 15 rd. magazines, and the mags would be expendable. This is partly why there are so many 15 round carbine mags around. Then there was concern (real or not I don't know) about leaving the magazines loaded for long periods of time and the springs taking a set. So the ammo was issued first in 50 round boxes, then later in the stripper clips.
The 30 round magazine was developed for the M2 (selective fire) carbine. It has a small lug on the left side to engage a lug on the late type magazine catch. This helps support the additional weight.
I think the 10 round charger was chosen simply because it is a convenient size for a bandolier, and would be less likely to cause problems than a 15 round clip. Of course loading one 15 rd. mag results in 5 rounds extra, but no carbine user would have just one mag. Three clips fill two mags.
A bit of box magazine terminology:
Double column, double feed. Like the carbine, M16, Thompson SMG, Mauser rifle, Mauser C96, etc. The cartridges are in two columns and feed from alternate sides. These mags can be loaded simply by pushing the rounds down into them, either from a clip or singly.
Double column, single feed. These are most hi-cap pistol mags, as well as the M3 SMG, and STEN. These must be loaded by pushing down the top round with the next round, then pushing that round to the rear. A magazine loader can be used to ease the job. There is one for the Glock and similar magazines, and a neat finger ring type for the STEN. For the M3 SMG, there is a separate mag loader; the M3A1 has one built into the stock.
Single column, single feed. The plain old M1911, P.38, etc. magazine. Generall low capacity, not hard to load and usually can be loaded and unloaded just with the fingers.
HTH
Jim
A bit of history might help. Originally, the idea was to issue carbine ammo in loaded 15 rd. magazines, and the mags would be expendable. This is partly why there are so many 15 round carbine mags around. Then there was concern (real or not I don't know) about leaving the magazines loaded for long periods of time and the springs taking a set. So the ammo was issued first in 50 round boxes, then later in the stripper clips.
The 30 round magazine was developed for the M2 (selective fire) carbine. It has a small lug on the left side to engage a lug on the late type magazine catch. This helps support the additional weight.
I think the 10 round charger was chosen simply because it is a convenient size for a bandolier, and would be less likely to cause problems than a 15 round clip. Of course loading one 15 rd. mag results in 5 rounds extra, but no carbine user would have just one mag. Three clips fill two mags.
A bit of box magazine terminology:
Double column, double feed. Like the carbine, M16, Thompson SMG, Mauser rifle, Mauser C96, etc. The cartridges are in two columns and feed from alternate sides. These mags can be loaded simply by pushing the rounds down into them, either from a clip or singly.
Double column, single feed. These are most hi-cap pistol mags, as well as the M3 SMG, and STEN. These must be loaded by pushing down the top round with the next round, then pushing that round to the rear. A magazine loader can be used to ease the job. There is one for the Glock and similar magazines, and a neat finger ring type for the STEN. For the M3 SMG, there is a separate mag loader; the M3A1 has one built into the stock.
Single column, single feed. The plain old M1911, P.38, etc. magazine. Generall low capacity, not hard to load and usually can be loaded and unloaded just with the fingers.
HTH
Jim