If you want a pistol to be a pistol then all the barrel you want or need is six inches long. You want longer, say 7 or 8? Okay you can do that, but all of a sudden you have a carbine with a lousy stock...none at all.
The charm of a pistol is its size and relative power, if you want to shoot .44 mags and such, from a small package. You want a bigger pistol, then I'd go for an Encore with a stock. You will end up with an accurate, light, powerful and quick little carbine, but it is not a pistol.