When I first got my Vaquero, same thing.
You have to experiment...like I did. The fixed sights are the problem...as well as your shooting "style"
you have to find a load that will shoot POA / POI ( Point of Aim / Point of Impact ) for your gun
I bought six boxes of .357 magnum, six boxes of .38 special...all different factory brands and went to work.
Me telling you my
POA / POI loads will not
help...as with every gun with fixed sights,
it's how you sight your target ( target picture ), trigger control, grip...everything.
Same thing with my Colt SAA...had to find a load that would hit where I aimed. Once you do....
BTW...wanna know why they make those front sight so tall...?!
So that you can file 'em down. ( Now, that's a whole 'nother story !!