My 4 5/8' Stainless Vaquero ikes the .38 SP load of 3.3 gr of Hogdons WST fired with aWinchester SP Primer pushing a 158gr either LSWC or Round F/P bullet. It prints very nice groups (Front sight modified "true" by Ruger factory during warranty repair) @ 21 ft.
This load has a mild report and low recoil.
The Oregon Trail bullets have proven out to be very consistant and their finish is without a doubt flawless, with no casting marks!!! They are just a tiny bit harder than other brands which aids leading. Velocity is claimed to be705fps with a pressure of 12,500psi.
the powder is at the bottom end of the scale.
We have tried 3.5 gr loads also with identical results, so to conserve powder we stuck with the 3.3gr fill for volume reloads.
The "NEW" Vaquero is a very strong revolver easilly handlong full factory .357 Magnum loads so you'll not harm it with such nice target loads.
Mine had some internal problwms causing warranty repairs. Essentially, Ruger rebuilt the insids and custom fitted each part producing a factory tuned revolver for me.
Turnaround time was 5 weeks and well worth it.
HTH,
ZVP