Yeah. It's designed by gun writer Wiley Clapp for a distributor. Has a three or four inch barrel with a Novak fixed rear sight and grips that are a checkered rubber edition of the earlier grip with the wood inserts. The back of the grip is checkered. Looks very nice in photos.
Join one of the Ruger forums and ask for someone to post a photo, or Search for one. You'll probably want one, if you like the GP-100. Don't know the price.
BTW, there have been some runs of the GP-100 with five-inch barrels, too.
NOTE: this was posted before I saw the photo on Page 2 here. I posted for you on the Ruger board that I'm on. Someone may post another pic there.
Need Photo of Wiley Clapp GP-100 Special - Ruger Forum Keep an eye on that thread.
I'm glad that you got both guns, and hope that you can repair the M-13. The best way to eliminate the endshake is for a KNOWLEDGEABLE gunsmith to put the yoke on a mandrel and tap it with a hammer to lengthen the yoke rod or whatever it's called. Some do use shims, but the former Dallas police armorer told me that the way S&W armorers taught him was to tap the part on a mandrel, I think he called it. That will correct the shortening of the part due to repeated recoil.
I think you'll like that Ruger, and if it's stainless, you can polish out any scuffs or scratches that aren't too deep. Stainless has a VAST advantage in a carry gun, especially in hot, humid climates or around saltwater.
Please do post photos. Let us know how they shoot. I'd have S&W fix that endshake and reblue the gun, but you're looking at some fairly serious money to do that. I'd have tried to find a M-65 three-inch in really nice shape and not had to refinish it or repair anything. As you might guess, in this case, I'd have bought the Ruger, if it's in better shape, and to get the stainless construction. Your short GP-100 probably has the smaller grip that Lett used to furnish. I think you'll be delighted at the way it fits your hand. But the longer Lett grip on my four-inch GP stuck to my hand in recoil and tore the skin. I replaced it with a Pachmayr Gripper and have been very pleased. Tackiness varies, and older guns are less likely to cause this problem, as the rubber seems to harden a little with age. Some Ruger actions and triggers are very much better than others.
Put a couple of drops of Break-Free down in your action and use the gun. It'll probably smooth up pretty well. But the SA trigger pull will usually have a little more creep than on S&W's. Still, you can do exceptional shooting with a GP -100. And the weight does handle recoil well.
You bought a couple of really good guns. Pity that the M-13 needs work. If it has the wooden service stocks, it'll kick a lot with .357 ammo. Pachmayr round butt grips will help. DO NOT use much of the hot 125 grain .357 ammo. It will erode the barrel throat and top strap and may split the forcing cone. Stick to 140-158 grain bullets. The heavier ones aren't needed, either, and will recoil more and probably increase endshake sooner.