What kinds of firearms would people start making [After the End]?

[phayman53]

I asked a question on this thread about firearm prices post-apocalypse that got me wondering more about what kinds of firearms people would start making a generation or two after the kind of civilization shattering events described in [AtE 1 and 2]. My question is only tangentially related to the one in that thread, so I decided to ask it in a different place.

The [AtE] line assumes that people would initially stabilize at about TL4 in terms of what kinds of new equipment groups could responsibly produce after a civilization ending catastrophe. So what kinds of firearms do you think people would start predominantly making at this point? Do you think they would make muzzle loaded rifles, or would they start with breech loading designs? Would anyone bother with smooth bore muskets, or would rifles with minie balls immediately be re-adopted? What about more complex designs, like the first cap lock revolvers--potentially usable in rifles (I would assume), but definitely TL5 tech? This is not a criticism of [AtE], it is a world-building question for trying to make a plausible, consistent feeling setting using the [AtE] rules where people are again making firearms with some regularity.

Some considerations behind my question:

Breech loading rifles were invented very early (TL4 according to [LT]), but never really caught on until much later. My basic understanding is that it was difficult at TL4 and 5 (and therefore expensive?) to make a breech loading rifle with a strong enough seal to not occasionally fail when firing, so the benefit of much faster loading did not outweigh the risks and cost. Would such a drawback continue in a post-apocalyptic TL4 situation given that people would know, at least in theory, that it is possible and preferable to make a reliable breech loader?

What about cap-lock revolvers verses single-shot? Would it be too difficult to regularly make weapons with tight enough tolerances to be a revolver, or would they be a fairly common newly manufactured style of firearm?

Lastly, what about cartridge bullets? Is it really that difficult to cast casings with tight enough tolerances and strength to work in a pistol or rifle, or would an essentially TL4 gun smith be able to do it relatively consistently given that the idea has already been invented?

I look forward to people's thoughts!