I don't recall that Daryl gave a date on the Lefever he posted the measurements for. I did note it was a "D M Lefever". This was the crossbolt gun Uncle Dan built from about 1902 - 1906 after he left the Lefever Arms Co.
I have 9 Lefevers (all LACs) dating from about 1889 to one of the very late Ithaca assembled ones & none of them have any significant taper to the bore which could not be accounted for by reamer wear. No more than a couple of thousandths till you get to the choke. They all have the taper choke with no paralell section at the muzzle. Those with full choke are around 4" long, lesser chokes are shorter.
I would really like to see the results of a statistaclly significant pattern testing comparing a "Taper Bore" with an ordinary choked bbl. I have been led to believe that a constant taper down the bore would shoot very much like a cylinder bore, that it took the constriction "At the Muzzle" to produce the choke effect.
I do not foresee a small taper to the bore, ending with a conventional choke (either taper or conical/paralell) having a significant effect on patterns. Good patterns have been, & still are, fired with both types of ordinary chokes.
