- cartridge storage in stock (store a multiple of two inside the stock body, can be opened/closed with a flap or latch)
- detachable stock with thumb hole, converting the pistol grip
- replace planned break action with chamber sliding out of the barrel, dropping cartridges on button push (per barrel) and chambering with a single push/insertion
- flippable iron sight for each barrel (no barrel calibration possible with Lego)
- maybe replace iron sight with some kind of primitive scope
- or in other words, keep to scoping as modular as the rest
- hence, detaching all other parts, too and storing them more compact
- keeping any locking mechanic inside the barrel/chamber grip (no barrel, thus only chamber)
That's all what I came up with. I've made many different models so far, but they also ended up using some things here and there that could be made better by using the space inside stocks and grips more efficiently. I'll also figure out how useful and, most important, how possible the slide-out chamber would be. Since there will be enough room under the chamber, it might be a good idea to think about using the space for such mechanics. Though I'm not sure where to put the push buttons then. Maybe it will simply not be possible due to space constraint, who knows. Anyway, the cartrigde storage in stock is what might be the most possibble feature I think. It's a side-by-side gun, so there's plenty of room without bloating the stock to look bigger than the gun itself. I love thus buttstock cartridges holders. But my cartridges are much bigger than normal ones and I don't need to watch out for recoil. So the stock looses it's recoil transfer ability and there no logical for using the now free space, I think. However, I might only be able to store a maximum of four cartriges there (surprisingly, I only have four cartridges available so far). It'd be a length of 12 studs and 18 studs for two more (making 6 then). Plus seperation elements it's 15 studs minimum. But I should not concentrace on it at first, otherwise I might end up with extras instead of function.
Oh and I've also seen a rather rare locking mechanic in a movie lately. It looked rather non-functional, but consisted of pullable barrel, revealing and halfing the chambers. So you put in your cartridges, close the lock and it's ready to shoot. Seemed a bit doubtful to me. It's probably not able to handle other things than shotgun shells or so.