Howdy
As CraigC says, in a perfect world, the cylinder is supposed to lock up at the same instant that the hammer reaches full cock. Practically speaking though, with just about every single action revolver I own, and I own quite a few of them, the bolt pops up and locks the cylinder in place just a tiny bit after the hammer goes to full cock. This is to be expected with a production revolver that has not been hand fitted, and Rugers are not hand fitted to that extent. If they were they would cost a lot more.
What you don't want is the cylinder to lock up before the hammer goes to full cock. If this happens, you may never be able to cock it. When the hammer is going back, the hand is rising. When the cylinder locks, the tip of the hand will jam against the ratchet teeth at the rear of the cylinder and will not be able to rise any further. This can jam the hammer and prevent it from going back any further. Practically speaking there is usually enough slop in the hole in the hammer where the hand pivots that the hammer will be able rotoate back just a tad more so it can go to full cock, even if the cylinder is locked.
I do have one 'original model' Vaquero that has a 'slightly long' hand. When I bought it, the cylinder locked at exactly the same instant that the hammer went to full cock. All the slop was taken up. When I installed a Power Custom half cock hammer in that gun, the new hammer was just different enough from the original hammer that the gun would no longer go to full cock. The cylinder locked up, and the hammer could not quite go back far enough to go to full cock. I removed a teeny bit of metal from the tip of the hand with just a few strokes of a file. Then, the hammer was able to go to full cock again at the exact same instant that the cylinder locked.
That is the only single action revolver I own that does that.
Usually, it is not a big deal if the cylinder locks a teeny bit after the hammer goes to full cock. Most single action revolvers have a bit of over travel at the hammer. You don't have to rely on momentum at all, you can cock the gun as slowly as you want. Just give it a firm stroke and pull the hammer back until it stops of its own accord. Most likely, the cylinder will be locked in place.
Try it and see.