barrel length question
Fixed sight Colts and their Italian clones as well as Ruger Vaqueros generally (with the exception of limited models, Sherrifs etc) come only in the traditional "old west/Colt" 4-3/4, 5-1/2 and 7-1/2 inch lengths. Adjustible sighted Blackhawks add a nice in between 6.5" which is particularly good for hot .357, .45 Colt and .44 Mag loads--the added length good for reduction of muzzle flip, fps and accuracy, while adding weight (unwanted if hauling it around). I find the 5.5" (Vaquero or Colt clones) to be the best of all worlds if carrying the weapon around a bit--in terms of balance (weight and aesthetics---but that's just me). A little extra length for sight picture, accuracy (a bit more fps) and reduced muzzle flip vs the 4-3/4" and handier than the 6.5 or 7.5". The latter two are more ideal for "serious" hunting however-though the 5.5 again is an "ok" compromise for such duty.
The most popular SAA (Colt format) guns are 4-3/4 esp among the cowboy shooting crowd and this is truly a nice, handy size; but if using it for more utilitarian duty, i.e, as a shooter, I'd prefer to load .357 guns with .38 Specials most of the time, .45s with ACPs (for those with dual cylinder option) or lesser .45 loads, and .44 Mags with .44 Specials in this shorter length. If you like adjustable sights and the prospects of occasional hunting, and value these attributes over "handiness," look for a .357 or .44 Mag Blackhawk in 6.5" as a great all-round SA. 7.5" only if mostly for "serious" hunting duty 90% of the time. If you like the fixed sights and charm of the "Colt SAA look," look for a nice 5.5" Vaquero (new or old model) .357 or .45 Colt or (old model) .44 Mag, and on the latter practice mostly with .44 Specials.