I'd like to put my two cents into this discussion if I may. I bought a like new 44-40 Vaquero at a gun auction some time ago. Bought dies, cases, bullets etc and started loading for it. It was an excellent shooter in 44-40 and then I got curious. After two phone calls to Ruger, I found out that both their 44 mag and 44-40 Vaquero barrels had the same specs, So then I decided to make my Vaquero a convertible if I could find a 44 Mag cylinder. After a short period, I found a 44 mag Blackhawk cylinder on Gunbroker, and immediately purchased it. The front bearing on the cylinder needed to shortened several millimeters, and it was then a drop in. Timing was perfect and it shot 44 Spec loads about the same as my 44-40 loads, Approx. 11/2'' groups at 25 yards.. Haven't tried, nor do I intend to try, 44 Mag loads. It was an easy conversion for me and I assume it would be the same for our inquiring friend..