I recently purchased a Smith & Wesson 638 to be a summer gun for my XDSC.
Well finally got to shoot my brand new 638 and ran into some serious trouble.
I bought a box of Federal "Range and Target" 130 gr. ammo.
After shooting 35 of the 50 rounds, the cylinder was noticeably hot in that I could touch it to open the cylinder, but I didn't want to touch it for very long. Well after those 35 rounds (shot and reloaded at a steady pace) I loaded the next 5 rounds (#36 to #40) and noticed the cylinder would not shut all the way. I kept trying to figure out where it might be rubbing, but could not link any particular point. After unloading and trying to figure it out it eventually cooled and closed properly. It was still warm, but opened, closed, and functioned perfectly so I set out to reproduce the issue with the remaining 15 rounds.
So for the last 15 rounds I shot rather hastily but still tried to work on form. After emptying the last 5 rounds I noticed it did it again.
Has anyone heard of this before? The first thing I thought of was that the frame is a different material than the steel cylinder and barrel, and therefore has a different thermal coefficient. At the same time, I was sure that this should not be an issue since the multi-material J-Frames have been out forever. The only other thing is that possibly dirt can get under the extractor, but it seems silly that so little rounds can cause this (ignoring the possible relationship with temperature that seemed apparent).
If this is to be expected, I am fine with that considering in a defensive situation involving a snubbie I hope to never need more than one or two reloads, but damn what a surprise this is.