Gear Rifles - design assistance requested

[Varyon]

Originally Posted by Anthony

The problem with the chain idea is that you have to move the entire chain to move the projectile, which means you have a large efficiency loss unless either the chain is very light, or you can keep the chain spinning between projectiles.

Hmmm... an excellent point. Two of the good reasons to use a chain (which I envision as a continuous loop on each side) are that the links themselves give something for the teeth of the gears to hook into, and that the cup can "slip" through some of them when it strikes the brake, so that the gears don't have to come to a sudden stop (which could damage them - and probably whatever chain/string is being used). For a string setup, which should markedly reduce the extra weight that needs to be accelerated, I feel we wouldn't want a continuous loop, but rather have one end of the string firmly attached to a spinning reel that would wind up the string. The "slip" would still be possible, by extending the string past the cup and tying knots in it (with a sufficiently large one at the end to make certain the cup doesn't slip off). However, once it's slipped past some of the knots, how would we get it back in front of them so it can slip next time?

Thinking on this, what if the tab (for pulling the cup back) isn't actually attached to cup, but rather to the ends of the strings? To pull it back into position, we have to pull the knotted portions of the string back through the cup. A large knot that it can't slip past, right in front of where the cup is meant to be, means when we pull the tab back, we pull the string back into proper position to allow slipping on impact, with the cup where it needs to be to be loaded. Does that sound feasible?

Originally Posted by thrash

Sounds as if you could be describing a scaled-up Red Ryder BB gun (HT, pp. 88-89). Skip the gears; use air as a working fluid. Put the piston under the barrel and back it with a strong coiled spring. Since you don't have to emulate a lever-action, you can increase the strength of the spring -- say, brace the butt on the ground and use two hands to cock it.

Not as delightfully clock-punk as a gear rifle, but certainly plausible. Real-world metallurgy and gun-smithing weren't up to the strengths and tolerances required, but you don't seem concerned about that.

Containing highly-compressed air - particularly containing it for a decent chunk of time (these weapons are meant to be able to be loaded, then go at least several hours without firing, if needed, like firearms) - seems unfeasible to me when limited to ~TL3-4 materials. While I'm certainly not wanting strict scientific rigor, it makes more sense to me that superscience (well, cinematic anyway) methods could yield clock-punky mechanical batteries than that it can contain air compressed to the many atmospheres of pressure needed to have a weapon that is competitive with muskets. Probably just my own idiosyncrasies. Also, with regards to clockpunk, [tantrum]IwantitIwantitIwantitIwantit!!![/tantrum]

Originally Posted by Fred Brackin

We already have an Orichalcum Spring Gun in DF6. It's basically a ST12 Crossbow with 8 shots but without those inconvenient arms.

Sadly, I don't have that DF book. But it does sound like the same general concept, yes (but I don't want to be reliant on fantastical materials... particularly given an ~indestructible material like orichalcum may well not even exist in Oubliette, not even within the dungeons).