Garandman,
Here lately there have been a ton of 4" 29-2's on Gunbroker. I just bought this one.
4" #N61195 shipped May 1972
I will say it actually measures 3 3/4" from cylinder to the end of the barrel. It is not unusual for barrels to be slightly short of advertised length (usually by 1/8") as I believe the barrel stock is cut to the exact length (4, 6, etc.) and then the crowning and finishing accounts for the shortening. 1/4" must have been a newbie and it took him a bit to get the barrel right
No 4" guns in the -2 arent rare, but I have seen more -3's