If you stay away from the oft mentioned "Ruger Only" loads which some have used to approach .44 Magnum performance, you can load anything that a Colt SAA will handle...which is considerable. Oft stated here and elsewhere, if you want a .44 Magnum, then buy one....the .45 Colt all on its own, and for over 100 years too, is no slouch for power in normal loadings, and the New Vaquero will handle it just fine.
However, you might find that the cylinder throats are too tight to handle cast bullets with good accuracy. (My NV had undersized throats.) A trip to cylindersmith cured that problem and I now have a gun that will shoot sub 2" gps at 25 yds with lead alloy slugs. BTW, it shot good groups with jacketed bullets before I had the smith open the throats to .4525". HTH's Rod
Our Flag does not fly because the wind blows against it,
It proudly waves because a soldier's dying breath blows upon it.
USAF Forward Air Controller, 5th Spl Forces,
An Loc, lll Corps, RVN, 69-70, Vietnam Vet '69-'73