Why ask, just carry both. I carry a Glock 19-26 and its way more weight than those two. Those are airlite guns. lol
To note though, I own both, and I really like the 642 (no lock model) way better.
SHTF vs TEOTWAWKI you ask? SHTF, just some crap on the ceiling and walls, TEOTWAWKI end of the world as we know it. Orignally made by 9mm/®™©