So I am quite new to the franchise. I've never played any of the games and basically have just been watching the anime for the last couple of days.

One thing that really irks me (as a bit of an armchair firearm historian) is the design of the anti-demon catridges. They don't make any sense. Let me explain:

A traditional cartridge consists of a casing that holds 3 components. The actual bullet which is being shot out of the barrel, the powder which when ignited propells the bullet and the primer which ignites the propellant. So only the front part of the ammo gets shot out of the barrel, the casing has to be ejected in another manner. The ammo in the show is supposed to deliver the green fluid into the demons body. But it is not stored in the bullet part of the cartridge but rather in the part where the powder would be.

So my only explanation would be that it might be a caseless cartridge, a type of cartridge that basically combines bullet and casing into a complete unit (like a miniature rocket). Otherwise the green liquid would never reach the demon. But then for a caseless cartridge there is not enough space behind the green liquid to hold the propellant.

The next step would be to assume that the caseless cartridge gets propelled by other means like an electromagnetic force. But their guns don't look like railguns.

Is there an in-universe explanation for that weird design or is it really just rule of cool (like Dante never having to reload)?

Is there a lore reason why the anti-demon ammo doesn't make any sense?