I bought my first Model 645 s/n TAK2138 from the first batch the Salt Lake City S&W distributor received, on January 2, 1986. The magazines had stainless steel sheet metal floorplates that, when you did a hard mag insert, with your mag hand slapping the mag into place with the palm of the hand, and then quickly moved the support hand forward and then down, to join the off hand over the strong hand, sometimes the floorplate's cut and swaged tab was unable to retain the floorplate in place. The floorplate slid forward, off of the magazine bottom, which then would lead to the mag spring, mag follower and any cartridges in that magazine, being enthusiastically ejected out of the bottom of the mag and gun. Not desired performance, especially in a big-time match!
There was another problem involving the sheet metal magazine followers and the magazine safety/disconnect. Upon discovery of both flaws, S&W issued a recall for the first few hundred 645 pistols.
I got the recall notice mailed to my house (I always filled out and mailed in the warranty cards.). S&W wanted me to return the pistol at their expense. I replied that mine was working fine and that, as a police officer I was not allowed to carry the new .45 by my department regulations, and so my 645 was probably going to be a range toy. I said I was still interested in having the new parts sent out, and if my original parts appeared to cause problems, I would have my local S&W warranty station install the new parts.
Surprisingly, S&W agreed to do this and mailed me four new magazine followers, four new springs, and a few other bits I can't now recall. They are still around here somewhere in S&W's little clear plastic bag.
I never had any problems with the 645 malfunctioning, so never used the parts; they are around here somewhere.
My new .45 ran flawlessly. The big, brawny pistol cycled perfectly, and the heavy, robust stainless steel construction and many sharp edges and corners combined to make a highly effective cudgel of the pistol should cudgle become a better option in a particular moment than shooting, with the corrosion resistant stainless steel keeping cosmetic values high.
I used my M-645 as my house gun after myself and friend Dennis Tueller spent an afternoon feeding the pistol every single cartridge loading of .45 ACP we could access, mostly factory but also many handloads. We fired over 1,600 rounds through the gun in a single afternoon with only one failure; one of my handloads done on my progressive Hornaday outfit had smashed the replacement primer into the primer pocket sideways. The pistol just flat worked.
Good pistols, that lead to a diverse family of likewise excellent huckers of 230 grain punkin balls. Good pistols indeed.