MAG weapon aesthetics

I've been meaning to ask this question ever since I got to the point I could start using MAG weapons, which was a few months ago, but I guess I was hoping someone had answered the question already, or I just couldn't be bothered asking it (until now that is).

My question has two parts to it:

a)

While I understand how the Laser and Plasma weaponry can function of a single, common magazine/battery that powers the device or provides it with a cell containing plasma that will then be formed and fired under a certain form that the weapon has been designed to accomplish, why is it that the MAG weapons, which are no longer energy-based weapons but now kinetic-based weapons, are able to function off of a single magazine type for all weapons; an example would be the pistol, which can be fired nine times, using the same magazine as the carbine, which fires three pellets six times until needing a reload, as well as using the same magazine as the MAG STORM, which can fire thirty times before needing a reload.

A possible explanation that I have for that actually comes from the Mass Effect series, namely that the weapon shears off a desired amount of material off of a block of material (in this case, provided by the common magazine), which is then accelerated to speeds of around Mach 5.

b)

Whilst the MAG Rifle, Carbine and Precision Rifle have the same sized magazine, that of the MAG Pistol is quite an amount shorter compared to the established "standard", although according to previous concept arts I've found the magazine was of a similar length of the previously stated weapons but was shortened (to make it more compact, maybe?). Additionally, I cannot see where the magazine for the MAG STORM would be inserted, with the exception of the round drum-like feature found on the side of both the STORM and the aircraft weapon, however that would mean a different magazine would have to be provided for the STORM compared to those of the "baser" weapons.

This is more of a complaint of the concept art than with the actual game (that can be changed more "easily" as it were), and I do understand that certain actions can be taken that make the coding and such easier.

For a game that puts so much detail into everything that it almost gets me giddy, I couldn't help but bring these two points up, and maybe (or maybe not) cause a hassle/headache for some people. Hopefully an easy answer can be found and provided.