It depends on which single action and which double action you are looking at. For instance, IMO a S&W revolver is more accurate than a Ruger revolver. So I would go with the S&W and just shoot it in single action mode.

However if you are only going to shoot heavy stout loads then I would look at one of the stronger single action designs. For instance, I also believe the Ruger is better for sustained heavy load firing than the S&W. So how much will you shoot the revolver?? With heavy loads?? If you are going to be shooting a bunch of heavy loads then the Ruger will hold up better than the Smith.

But then you could look at one of the better single actions like the BFR or the Freedom Arms. Or you could buy the stock Ruger and have a little work done to it.

So it really depends on how much you want to spend. And how many heavy loads you will really be shooting in the revolver. Tom.