Thank you all for your responses! ...and, yes, the 4596 is a Lew Horton gun with a square trigger guard. The factory says about 380 were made all on the same day in 1990. I bought mine in 1990, which was as soon as the agency I was serving would permit .45s. I've carried mine since. In about 20 years of service and approximately 14,000 rounds, it has had virtually no malfunctions, stoppages, etc. and only one problem: Two months ago I noticed a crack in the main body of the safety/decocker. S & W replaced the part totally free of charge (they even paid the shipping) and returned the gun in about 15 days. I was astonished at how good their service really was! They did all that was promised in the warrantee, no hesitation or nonsense.
I'd like to know some more about these excellent weapons. (1) Why did Lew Horton have them made; (2) How many are still in service? (3) are other 4596 owners experiencing the same reliability in daily service? I'd be grateful for any information you can offer.