The thing with the thunder 380 is they are full of all kinds of gunk. The springs are really tight and they are a little finicky as to what ammo they use best. If you take them down and clean and re lube them well then for the first box or two run some hot ammo through them they tend to calm down a little.
Like most 380 weapons they are pretty small and that lends itself to more things you as the user can do wrong when firing them "limp wristing" is common in causing them to not function well as well as bigger man hands getting on things they don't need to.
The 380 can be a decent weapon for CD but with most of them there is an issue here and there. I personally think one is better off with a compact 9mm if the small gun is what the would be shooter wants most. They are built more solid and are a little bigger allowing for a more natural grip. A 380 is what people like my Dad would have called a belly gun or pocket pistol. The round has a good bit of snap for such a small round but I think that is mostly due to the compact size of the weapons that use it. A good grip it seems to me anyway is much more important with these weapons. I've fired many over the years and more often than not failures are caused by grip or the weapon just not liking the round that's in it.
Glad to hear your having better results wit the new one. Those Bersa's are pretty good but they need to be broken in with a little more patience it seems. They can be trusted though as well as any in their class once they are cleaned, lubed, and broken in properly. Also sometimes it takes getting a few different kinds of ammo before you'll find the round that works best. Mine did not like those flat point Winchester rounds but I had found an East European surplus ammo that worked real well. It was a round nose FMJ round that was a little hotter though too.