Good grief, that's still a massive jump considering spring-loaded magazines don't really even date back all that far. I mean, I'm not gonna lie, I've brought guns into a fantasy setting before - those being revolvers and some kind of handheld cannon. In hindsight, revolvers are definitely still pushing it... but as far as technology goes they're probably better? 

Regardless, it'd just be best not to bother with them if they didn't actually exist in the first place.