So, just thing that popped into my head while on the bus home..
Cyberware option for arm parts, replaces largely the whole forearm between wrist and elbow. comes in 2 options of Internal Magazine for pistols. Works best with smartgun capable weapons.
First option is sort of a secret magazine holder, arm is largely empty but can hold say, for average human, 3-4 magazines of pistol ammo, though this can change with what type of ammo, possibly a ton of hold out or light, or maybe 2-3 heavy pistol mags. further adjusted for meta humans as trolls would have much more room to hold, dwarves maybe little less. Further options if your willing to go with obvious cyberware being a little bulky.
On gun with smartlink and compatible with the magazines when you run empty, or wanna do a tactical reload, port opens up and little mechandrite pops out snagging the old magazine and fits in a new one, safely stashing the used one away for future reloading or if you just need those last few rounds when things are tight.
This gives the option of also having Alt mags, one loaded with plain rounds, another with gel rounds, and another with AP or Explosive, or whatever horrible thing you want to unleash.
In game effect is reloading is now a free action, and can be done with both hands full, and quick access to diff types of ammo.
Second option goes a bit further: rather then the rotary assembly holding different magazines, the arm is converted into something like a helical magazine like on the Bizon pp19, Calico, or danuvia vd-01, a spiralling feed system that can hold an upwards of 50-60 bullets inside the arm. When you pick up your pistol and activate it a small "belt" (but without links or other such) feeds into the pistol and starts loading rounds right away supplying a huge amount of ammo for your sidearm in a firefight, being very useful for people who enjoy machine pistols and uninterrupted amounts of "spray and pray".
This option provides much more ammo, but doesnt have the option of different load types, costs much more essence, and issues with weight and balance as the arm gets lighter as you fire. Not to mention what a bad hit to the forearm could do if the ammo cooks off..
Thoughts from you guys?