The NV is just as strong as a
post war Colt and Colt clones, 45 Colt SAAMI spec is 14,000 psi so I'd recommend not going over that. With that in mind you can get 255gr bullets going ~1000fps and stay under SAAMI spec for 45 Colt.
Ruger has advised the industry that the New Vaquero must not be fired with loads exceeding industry pressure standards (14,000 psi). If loading for a New Vaquero, use the standard pressure data in loading manuals and you will be good to go.
dmsbandit The NEW Vaquero is NO STRONGER than a 1873 Colt Peacemaker. eek DO NOT shoot any load in them that a Colt or Colt clone can't shoot. crazy They are NO WHERE near as strong as a model 29 or the older Vaqueros.
I NEVER advocated using "Ruger only" or "T/C loads" in the new Vaquero, they will handle FACTORY SAAMI spec ammo. I did mean the N frame .45 Colt guns, not the .44 mag, my bad on that typo.
AGAIN, I said modern FACTORY ammo.