How hard is it to get these things? My husband wants to get me a Ruger Mark III competition 22 with the slab sides and a 2 1/2 x 7 Nikon scope. It comes with a thumb rest built in the grip. I don't want to shoot with a glob of wood in my palm, I want a thumb rest on the right side of the gun not the left. Can't gun dealers order these things left handed?