The original Vaqueros were built on the large frame and are as strong as the large frame Blackhawks and Super Blackhawks.
The post-2005 New Vaquero is built on a smaller, Colt SAA-sized frame and is not strong enough for Ruger only loads. Although the .45's can be safely loaded up to 20-21,000psi. The New Vaquero is not as strong but they are a more precisely built sixgun. Having their chambers cut one at a time with the same reamer. Rather than all six at once. They are also built on new CNC machinery and are typically better guns. They also feature the "reverse indexing pawl", which is no more than a freespin pawl coupled with a spring loaded plunger that engages the ratchet teeth so that the chambers line up with the loading port at the audible "click".