Daryl, I appreciate you taking the time to provide those Crossbolt Lefever bore measurements. I saved both for future reference.
It is interesting to see that the measurements do not indicate a continuous straight taper all the way to the muzzles, but rather utilize a relatively straight taper for most of the length, and then have a greater angle of taper for the last couple inches. This would seem to indicate that Dan Lefever was aware that a continuous straight taper was not as efficient, as noted earlier by Rocketman.
I never really doubted Dan Lefever's words when he said he had used a tapered bore system, because he was always an innovator. And tapered reamers are certainly nothing new. But of the relatively few Syracuse sideplate Lefever guns I had checked, all seemed to have a straight bore from the end of the forcing cone to the beginning of a roughly 2/12 to 4 inch tapered choke at the muzzle end. Bores in 12 gauge guns were typically around .729" to .731" diameter. Some were checked with a Stan Baker bore gauge, and a few were checked with plug gauges in the course of removing barrel dents. The guns I had checked that appeared to have had barrels shortened by 2 inches or more had very little or no choke remaining.
I had carefully checked the bore diameter of an H Grade I bought that was advertised as a 12 gauge. It turned out to be a 10 gauge, and it is the only 10 gauge H Grade Lefever I know of. It has the Twist barrels commonly found on H Grades. It too has a straight bore with a conventional choke taper. As I recall, the bores were around .770" and the muzzles were about .745" and .755" diameter.
I only have two crossbolt D.M. Lefever guns, an O Excelsior Grade and one unmarked that is equal to 8E Grade guns. I hope to soon find the time to check both of them to see if they also utilized the tapered bore system. And it would be interesting to know if there are any Syracuse sideplate guns that have this tapered bore system, since Dan Lefever was still at LAC in Syracuse when he made those claims.
