Hmm.... 3500 rounds is a lot through a little pistol like that.
Not saying that the gun won't take it, but the spring getting the
snot pounded out of it doesn't surprise me. Smaller guns
with "compromise" recoil springs like an officer's model and
other subcompacts tend to wear out springs faster because the
springs are shorter and the recoil is more abusive. Might be worth
having a spare spring around. If you practice with it a lot,
get two springs, test both in the gun, practice with one, carry the
other. Probably cheap insurance.
FWIW, a friend of mine, the frame on his SW99 compact ended up
cracking and a chunk broke off towards the bottom of the frame. (we
couldnt find the piece, it occured during shooting) He sent it to S+W
and they gave him a new frame a week later. Never had a
problem since.
PS: is that lube I see on the spring?!?!? I think lube on the assembly
was part of the reason the rod warped in my SW99 .45. (Just a hunch, and
I have nothing to back it up... except that when I kept the new rod dry it did
not warp. )
-Mike