I cannot get into a ton of details, but I am aware of some of the back side of this.
Not buying the Marcinko thing, but it's his book so he can tell it the way he wants. I heard it different from a non-book writing source on Wegener and his initial 2.5" Model 19.
The reality outside of the gun itself is the time, and ammunition. A lot of the CT teams were training together back in the 70's and 80's. 9mm sucked in those days, and was often ball. This was sort of the last glory years of the revolver, and that is where most of the good bullet development was, especially in anti personnel rounds from the L/E world versus military stuff. You can do a lot of different things with a .357 revolver. Training loads, low penetration, high penetration, super blasty stuff (they were jokingly referred to as ".38's with a flash bang"), and tons of bullet configurations. The beauty of the Combat Magnums and the French guns was they could have the sights adjusted to do some very surgical work with any load selected. These guys were VERY good with revolvers. The SF guys from our side of the pond at the time also loved the .357 revolvers and most had very good skill sets with them along with the 1911's and BHP's. Also keep in mind that those 1911's and BHP's were not as reliable as legend persists, especially with any kind of non FMJ ammunition. Close quarters work inside an airliner (especially when backed up with a guy behind you with an MP-5), or vehicle, where you were moving people physically and extreme close shots and contact shots that needed immediate incapacitation made the .357 magnum revolver a very viable tool in this role.
I made a phone call on the grips. The story was a little fuzzy but they were a gift from and the quarter had some significance from who the grips were from.
Sorry for the vagueness, but I respect that much of the stuff from this world should not be in books or on the net.