I have a Peterlongo hammer Bchsflinte (Cape gun) in 7x57r and 16. I just got around to measuring the 16 gauge bore (as best I can), and discovered it seems to have a steady taper from a 16 gauge chamber to .622 (at the muzzle.) Anyone heard of 'vena contracta' bores in Austrian/German guns of this vintage (1920's)? And what was supposed to be the point of these tapered bores? (I have not yet made the gun go bang, but look forward to patterning it.)