came along to late as most LE depts were leaving the revolver and transitioning to autos at the time the .41 came along.
I have seen this a few different times (a couple of different ways) and I have to wonder, where is this coming from, and why does it keep coming up, because it is flat out WRONG!!!!!
The .41Mag came along in 1964, and was around for a couple of decades (20 years+) BEFORE "most LE depts." switched to semi autos.
in the 1960s, 99.9% of the police used revolvers. In the 1970s 98% used revolvers (there was one (1) state police that adopted a semi auto in the 70s. 1 out of 50 is NOT "most)
Police interest in the semi replacing the revolver began in the 80s, and picked up speed in the mid-late 80s, and I wouldn't say "most" police until the mid 90s.
The .41 Magnum came along was examined, tested, and rejected by the police at a time when the police were still virtually "revolver only".
It didn't make the grade as a police round because the police didn't want a N frame magnum revolver firing magnum ammo larger than the .357. Very few police depts. got to test the gun with the "police load" ammo, most only got the magnum ammo, and it was simply not suitable for police use. the few that did get to test the 210gr LSWC load thought it had potential, but didn't want an N frame gun (too big, too heavy).
The .41was NOT "doomed" by the police switch from revolver to semi, it got the thumbs down from police DECADES before that.