I have to agree with dacaur. My wife's first gun was a gorgeous Bersa 83 (basically a thunder) and the only way she could use it was in condition 1. That's all well and good if everything works perfectly but as we all know if you cant properly operate a weapon you cant depend on it.
We ended up converting her to a 3" SP101 .357 Mag which she uses with .38 +P ammo.
Interestingly, I picked up a new deep conceal gun for myself that is locked breech and is easy to operate for both of us. It is a Sig P238. Pretty pricey, and you have to make sure to break it in and make sure you get a "good one", but if so it is a sweet heart. Mine has a good 750 rounds though it, mixed factory, reload and high power SD rounds with zero FTF/FTE. I gave the feed ramp a quick polish with a dremel and some mothers mag polish and made sure to clean and oil it well after each range session when I first got it and its been flawless for me.
In short, I feel your pain. The Bersa is an excellent gun and an easy one to shoot. Its a shame to give up on it but you really wont be happy if you try to lighten the recoil spring enough to make the slide easier to work. The good news is if you do have the cash to pick up a locked breech .380 you will find it even easier to shoot than your Bersa, believe it or not. I dont own a gun that I can put multiple shots on target with any faster than my P238. Those big Sig sights just seem to stay glued to whatever you are aiming at no matter how fast you fire.