FA is probably known as the premier maker of single actions from a "factory" with quality that is unbeleivable in fit and finish and accuracy but it is expensive. F
A also offers a fair amount of options to personalize the handgun from a list of available options. the customs can be tailor made to your desires with features off other guns sized to your desires; anything safe goes....
additionally, the customs are mostly blue ... or color case hardened... and well blued at that... and the hammers can be blued as well...there is no safe limit on the options that you can imagine discuss and design...
the customs are super well made, fit and finish is superb, accuracy is typically outstanding, and the customs can most often handle more powerful loads than most factory guns of the same caliber... due to the close tolerances, tight fitting of parts that since they do not move, can take much more pressure...
except the FA which is also built very tight...
one other difference is the custom guns often have ample cylinder for long overall length rounds, but the fa's are slightly limited in overall length of the rounds it will operate with.. not terribly limited, but there are limits. If you want blue, it is custom.. if you want stainless you can have fa or custom...
the custom big bif bores are often made in the bisley configuration.. the fa's have their own grip style that is not quite ruger, not bisley, not colt....it is fa.
It is a lot faster to get a gun from fa than from a custom smith... you send the smith a base gun and then with 16-1900 bucks and almost a year for a lot of them ... you get back what you determined to be the ultimate six gun for you according to your experience, needs, and fancy...
that is all I know .. there is a lot more...
there is great pride of ownership and great investment in either one or both..
get either one first.. you have to get both anyway...
that is the ultimate truth... even got Lloyd... wow.
dk