In the BLACK POWDER GUN DIGEST 1972 on page 279 it shows the TINGLE SINGLE SHOT TARGET PISTOL $64.95
Says it "A choce of serious target shooters, the .40 caliber pistol is available with a 8, 9, 10 or 12 inch rifled octagon barrel mesuring a true .400 from land to land, fitted with hand filling lacquered walnut grips: adjustable rear sight, fixed blade front: blued finish: weighs 33 ounces with 8 inch barrel.
Because it is talking like the gun has grooved rifling and you say your mystery gun is a .45, it may not be the gun you've found, but it might be similar.
This guns grip looks like a Colt C&B with a square back trigger guard and the barrel seems to have some sort of under-rib that is shaped similar to the Remington C&B loading lever.
My old 1997 edition of the Blue Book of Gun Values" which is the last good book covering older muzzleloader companys and the guns they made, does not mention Tingle the Gun or the Company.
The red colored book, by the way, has long been out of print, but sometimes at a gun show you can find a copy.
Although many of the guns it shows in the back of the book (like the Tingle) are no longer in production 99.9% of the information in the well written and illustrated book still applies today. Articles on C&B, .58 cal muskets, the original Mowrey, TC Hawken, care and feeding... are all interesting.
Buy it if you find it. ::