Timing tradeoff
The bolt (on Colts)/Cylinder Stop (on S&W and Rugers) are timed such that they rise and engage the forward leading edge of the cylinder stop prior the completion of the cylinder's rotation.
Now, on most guns, it should rise about 1/3rd the way between cylinders. One could time it for slightly later, but one runs the risk of the hammer falling and hitting off or unreliable ignition. On most "police" revolvers, it was supposed to be timed to rise when the cylinder was halfway through its rotation between chambers. This was to ensure that the cylinder would be arrested and not skipped over. Recall that when police were armed with revolvers, they were taught, for the most part, to use the revolver in the DA mode. This meant quicker rotation than SA. Thus, timing became more critical and if the cylinder rotated faster than the cylinder stop popped up, discharge was not ensured and we could have one dead officer. Thus, the earlier rise of the stop on a police revolver. Of course, the tradeoff of this earlier timing is the prominent line you see on the cylinder.
