Originally, Altamont grips made to fit the Medium frame New Vaquero and Flattop-sized Blackhawk were marked NVB. Later, Ruger changed the nomenclature of the New Vaquero to again, just Vaquero. We now have Vaquero, New Vaquero, and again, Vaquero. Confusing? it is if you've not had a reason to stay on top of this.
So now, if you had grips that said NVB, but your brand new medium-frame Vaquero is now just called a Vaquero, you might not think these NVB grips would fit.
So now, for simplicity, let's stamp these grips with MVQB.. They fit the Medium frame VaQuero and (medium frame) Blackhawk.
Identical Altamont grips for a med-frame New Vaquero or Flattop Blackhawk, can be found with both NVB and MVQB engraved on the inside of these grips, and others have asked the same question.
.