16mm or .630 is a tad overbore, but not excessively and not uncommonly for other brands.
Polywad to the rescue.
Pack a box of their 20ga spread loads and hit the early grouse woods.
No worries.
Not excessively or uncommon for other brands, when? This gun was built in the 1940s, long before plastic shot cups were in use.
What was the point of a backbore of .015 when your wad was felt, circa 1948? I've seen Darne guns that were pre-war with the same 16mm bore. I don't know exactly what they were after. I assume it tightened the pattern up slightly with old felt wad ammunition, at the risk of blown patterns with heavier loads, and tightens the pattern to the next constriction, say, modified to full, with plastic shot cup ammunition.
It is choked too tight for the type of grouse hunting I have done with it. That point might be difficult for someone who has never been in a northern MN. grouse woods to come to grips with, especially in the first 40 days of the season. 25 yards is a very long shot in that setting. I have no plans of opening it, I have others that will do. I actually have good "depth" on sliding breech guns choked for grouse hunting, either of these will do nicely:
I eschew spreaders as I usually have a pooch along for the day, hell, I wouldn't hunt birds if I didn't have a dog.
I'm not convinced the "spread" of spreaders is very well controlled, or, predictable.
Karl, have you ever measured the bore of those different guns, and discovered how close to industry spec they are, or, aren't?
Best,
Ted
