I have had this item held for me at the Trading Post for a couple of weeks now. It's a Thompson Center Contender single shot pistol in .222 Remington mounted with a Lyman "All American" 4X rifle scope. I bought the gun to use as a platform for my new 5mm Remington Rimfire Magnum carbine barrel but decided to run some handloads through the Deuce barrel just to see how it functioned. I found some once fire brass that would just fit in the action and loaded 19 grains of IMR 4198 under a 50 grain Speer "TNT" HP.
It was a little awkward shooting a handgun so close to my eye but luckily the .222 doesn't kick too much. The 100 yard target is attached. At 25 yards it put them all through the same hole. Tried 4895 powder as well but preliminary tests show that good 'ol 4198 delivered groups about half the size at 50 and 100 yards.
I think I'll be hanging on to this barrel for when I get tired of the 5mm or need a little extra range.~Muir