Howdy
I'm curious why you think .007 is too much of a gap. I have many, many revolvers, most of them have gaps between .005 and .008. They all shoot just fine. I do have a few with gaps as small as .003, but I don't really see any problem with a gap a little bit larger. As a matter of fact I have one antique S&W, made in 1881, that has a gap around .012, because the frame was stretched by shooting too many Smokeless rounds in it. I was a bit concerned when I saw how large the gap is, but it shoots just fine too.
Hondo44 is correct. The standard way to tighten up the gap is to turn the barrel in one more thread. Doing this requires relieving the shoulder by the amount of one thread, so that the barrel can be turned in. Then, the barrel is trimmed back the amount needed to get the desired gap. I doubt Ruger will do it for you, you will have to find a gunsmith to do it, and frankly, I don't see the need.
P.S. Don't forget, the proper way to measure the gap is with the cylinder pushed as far as possible to the front. If there is any endshake (front to back play of the cylinder) measuring the gap with the cylinder pushed back will give an erroneous reading of barrel/cylinder gap.