I had the opportunity to get a real close look at this rifle a few years ago during a tour of the MHS archives. The number of firearms in this collection is absolutely astounding. I didn't have time to take any measurements but I can tell you what I know. First, my initial reaction to seeing this rifle was, "No one would build a Longrifle like that!". It has many characteristics of an ENGLISH FOWLING PIECE!!!
It has a long, maybe a 42 to 44 inch swamped barrel, didn't check caliber. Barrel is held in by three wedges with oval steel wedge plates, finely engraved. The plates closest to the breech had rounded "wings" top and bottom. It is NOT a hooked breech rifle and the tapered engraved tang has a "thumbnail' finale. The barrel does have a gold band at the breech and a round gold plate on the left flat engraved with "PC". The rear sight was a typical flat top sight and the front sight was the type where the blade is inlet into a groove cut in the barrel flat.
The lock is the of the typical English waterproof variety marked "ROGERS & BROTHERS WARRENTED". Flint, converted to percussion. The lock is held to the stock with two lock bolts ( no side plate) with simple round washers inlet into the stock, much like an English Fowling piece.
The nose cap was nothing special, just plain iron with a shallow RR groove and no engraving.
The ram rod pipes are round with a raised band near each end. The entry pipe has a double thumbnail and the finale is tapered to a point, again like an English Fowling piece.
The toe plate is rather long with a thumbnail finale and the patch box release is located on it.
The butt plate is typical of the period with a rounded top and a raised band, like the RR pipes.
The patch box is very elegant with well executed side plates, and a nice pineapple finale, all engraved.
The cheek piece is of the rounded English type, rounded and well defined. It has light "step" where it meets the stock and is adorned with an oval silver plate engraved with an eagle clutching arrows and an olive branch. It is secured by one screw in the center.
The trigger guard, English scroll type and the rear extension has a thumbnail finale and the front extension is a finely engraved pineapple design,,,, again, think ENGLISH...
The triggers are of the "set" type with a straight front post and deeply curved rear trigger.
The stock, maple with an English type checkered wrist, with a silver engraved oval on top. I believe the initials were WC.
The only carving on the rifle is the step around the cheek piece, a step from butt plate to checkered wrist and a step with an incised line running the length of the fore end. This step ends in the typical curvy line at the rear most wedge plate.
Much of the hardware was engraved in fine English type engraving and there was a lot of the Wiggle type border engraving too.....