This apparently is not a common problem with this model but if it helps one person it will be worth this entry. I bought a brand new New Vaquero in mid-July in .45 Colt. Sometimes the system would work okay and shoot nicely, other times it would lock up with live rounds in it. Trying to make a longer story shorter I thought I was experiencing base pin "jump" from the recoil. I bought new custom base pin from Belt Mountain in Montana...it is slightly larger in diameter and has a set screw to hold it in place. It seemed to do the job at first but I still had the problem. Yesterday, took it to the range and started to load the cylinder and with four live ones in the cylinder would not turn. So, I thought I probably should clean it better. Had to remove the cylinder to get it unloaded. Cleaned it thoroughly. Today, same brand of ammo it happened again. So, I took it to a gunsmith. By this time I was starting to figure out that the facing, or recoil shield, whatever you call it, directly behind the cylinder had not been polished or machined down enough. It was close so some brands of ammo might work and others maybe not or maybe a mixed thing with any brand of ammo. So, the gunsmith checked it out and said he thought that was exactly what was going on, that Ruger had not polished it down enough. He tried to do some polishing so I would not have to send it off to Ruger but called me and said that it needs too much polishing to get the clearance correct and that I should send it off. So, that is what I will do. I am telling you this so you don't go through what I did. When I first had the problem with I was at the range and could not get the cylinder out and could not operate the mechanism at all and had 3 LIVE rounds in it. I took it to a gunsmith who took it apart and told me that he could not find anything wrong with the gun. I paid him $18, not a lot, and now paying this gunsmith, and now finally shipping it to Ruger. So, if you have this problem it is slightly possible that your frame needs some work also. Today's gunsmith told me that his shop has sold many of these Rugers like this and have never seen this problem before and have never seen any either, by the way, with problems involving base pin jump. For what it is worth.......that is it.