I had one of the first 3913's (back in the late 80's) and carried it as a primary weapon for several years. It truly was a slightly fired gun, probably fired less than 750 rounds in the time I had it. One day in the range, I noticed accuracy was bad, even for me. Upon examining the gun, I found that the rails on the frame had worn to such a point that the slide had the freedom to travel about 1/8" up and down. The front of the slide moved up and down probably in excess of this 1/8". Needless to say, that was where my accuracy went.
The gun was returned to S&W, who replaced the frame under warranty, but when the gun came back it's POI was about 8" low and 6" right at 7 yards. Obviously, the 3 dot fixed sights offered no help in adjusting for elevation. I got rid of it. (I bought a new one to replace it, still in my safe somewhere, but never shot or carried it). I had lost my confidence in S&W as a carry gun since the early 1980's.
I purchased the gun brand new (transition from a S&W M-66), so I know how it was treated. This gun *never* ever fired any +P or +P+ ammo, all ammo was standard pressure 115 gr JHP or ball.
I always liked the size (compactness) of this little gun, but it turned out to be way too fragile (for no apparent reason except bad metal in the alloy frame) for my taste.
I never found where I had inadvertently pressed the hidden auto self destruct button.
One of my concerns over any used S&W alloy framed auto since this incident has been special attention to the slide to frame fit.
Hope this helps.