"Oh hey, I need recoil springs for my gun. Better check Brownells. Oh look, spare mags on sale? I'll get three just in case. Hmm, I'm going to need some extra magazine springs too..."
$500 dollars later, you're staring at your order confirmation thinking "why did I just buy a sight pusher for a Beretta Cougar?"
Brownells is like Target for gun people. Go for recoil springs, spend $500 bucks.