Sport,
There are many "practical" reasons for different designs of mag followers. Some are cheaper to manufacture, i.e., most are stamped. Some are designed for supposed superior function, such as polymer compounds for lubricity with the surrounding metal parts without a "wetting" lubricant (oil).
Think about the functional requirements of a mag follower. Then look at the different designs and you can see how they emphasize different requirements. That is a truism of hardware design.
The most important requirements are: <UL TYPE=SQUARE><LI>the follower must move through the magazine smoothly, maintaining a consistent angle throughout it's range of travel<LI>the cartridge must be presented to the returning-to-battery slide in a consistent manner, i.e., same angle, same height, each time and<LI>the follower must operate correctly with frame-mounted functions such as the slide stop, to catch the slide open after the last shot has gone.</UL>
I have dispensed with quotes from mfg's functional descriptions and used my own descriptions.
The last of the above is truly a function of the follower and the slide stop alone. The first two are functions of how the follower moves through the magazine body, so the interior smoothness and consistent shape, from top to bottom, of the mag body is part of that function.
Chip McCormick, for example has designed a follower of heavy gauge metal that is folded so that the view from the front of the follower is an "open jaw". The top leaf is the follower, per se, and the bottom leaf is shaped to engage the slide stop. It is easily removed, but under normal use maintains its position throughout its range of travel. The top and bottom leafs may be shaped, bent, ground, spread open, squeezed closed, etc. to meet individual magazine-to-slide requirements.
The shape and position of the lips of the opening of the magazine body, the material, position and shape of the follower and the design of the spring are all vital, interrelated functions of the operation of an automatic pistol. Not to mention the shape and angle of the loading ramp, the shape of the bullet, weight of the return spring ... ad, seemingly, infinitum.
One thing leads to another. One thing affects another. It is a system.
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Sensop
"Get your mind right and the body will follow." - Shino Takazawa, sinsei, hachi dan, Keishinkan do.
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