I have a M&P Target #648366 with a gold bead front sight. It has the slickest DA trigger of all the Smiths I have owned or shot, including a couple Performance Center guns. You’ve got a real peach there.
The slickest trigger of all you have owned MAY have been the result of the TLC afforded all S&W targets of the time----never mind this TLC was focused on single action use----or least seemed to be that way to me. I don't know when this TLC started---nor when it ended---if it ended, but I checked the S.A. trigger pull on the 14 M&P targets in my collection of target guns. These guns ranged from two 1902 versions to the last (from 1936). As an aside, the specification for S.A. trigger pull on targets was 3 to 4 lbs. (5 to 7 on fixed sight guns). At any rate, the S.A. pull on these 14 guns was 3.5 Lbs.----right down the line---from 1902 to 1936---at least.
Here's what's what from the 1925 Catalog (This from the M&P Target page.): "-------a special type of trigger pull is desirable-----not by any means simply a very light pull, but one having the peculiar quality termed "short and crisp" by shooters. This not only requires a special type of notch and trigger point, but requires a different adjustment of the working parts of the action as well." (They neglect to tell us which working parts of the action---or what sort of different adjustment, but that's understandable seeing as how anybody could be reading this catalog---and very likely were reading it!) I'd for damn sure be reading it if my paycheck came from Colt!!
Ralph Tremaine
Speaking of Colt (and I've told at least part of this story before), I had what we came to call "a Roper Colt". It was an Officers Model 38. It'd been to Roper's shop, where his lads had their way with it----grips/sights/action job---and some cosmetic alterations (polishing the leads into the cylinder stop notch leads, and left them "in the white" such that there'd be no visible turn line)---very sneaky!!
At any rate, part of the action job consisted of the use of a hammer, the likes of which bore no resemblance whatsoever to the stock Colt hammer. Needless to say, the geometry was the same, but the profile wasn't even close to the same!
I took this gun to my gunsmith to show off. He sat there on his three legged stool, wearing his leather apron, and puffing on his pipe; and said, "You know, I hate these effing Colts, but whoever did that action job REALLY knew what they were doing!!" High praise from a very sharp guy!!
I wondered who in the world could have made that hammer without it costing a gazillion dollars. It took awhile, but I finally came to the only realization that made any sense: Colt made it---only they made it to Roper's specifications---which involved a trip to their milling machine where it got a new shape----and lost A LOT of weight!!
A belated thought: If you want the slickest trigger of all you've ever owned, break loose of $20-$30, and get yourself a Miculek spring kit. Stuff it in----EXACTLY as you're told in the instructions, and you'll have it. If ANYBODY knows what's what with the innards of a S&W hand ejector, it's Jerry Miculek! And with this spring kit you'll have any D.A. trigger pull weight you want! Note he tells you to not go below 7 lbs. lest your toy won't go bang.
Now the reason to install it EXACTLY as you're told is because I didn't---the first time around. I've been in and out of 200 and some odd S&W hand ejectors in my time, and I for damn sure don't need any instructions to tell me how to swap out a couple of springs!! Well, maybe---and then again, maybe not. NOTHING would move when I finished---the first time around! Okay, maybe I better have a look at those instructions. Everything worked just fine---the second time around. Again, note you can have any weight D.A. trigger pull you want!