I don't know the guy or anything about him. I'm just going by the numbers that he had given.
I do know that various companies had different ways of doing their things. I have a late 70's stevens break action single shot and depending on how you measure it, is anywhere between .6245" to .6310"
Either way really, we're only talking a few thousandths of an inch of what he had listed as full. And I'm sure the stress of as many shots as has been put through it has stretched the muzzle some. That's only natural on a gun that's been well used.
My stevens barrel, best I can tell is not marked what choke it is. Either on the barrel or stamped into the lug either. I grew up under the impression that it was a modified choke my whole life because someone told me it probably was. Only later as an adult did I stick a set of calipers in it to check for myself, but it's most likely a full choke. Which would explain why it always shot so well.
Truth is, I own a lot of 12, 20, and 410 shotguns too. Many with screw in chokes that even with extra full or turkey chokes, still doesn't shoot as well as my old stevens. I've missed squirrels with other shotguns that I thought were good shots that should've knocked them down that obviously didn't.
I spent a lot of time with that stevens when I was growing up and being my only gun, was really good with it. Even last year, every time I hunted with my youngest son a couple of times, that's the one I carried and it's still shooting as well as ever.
I bought this shotgun for next to nothing and just wanted it to shoot better because I wanted to try hunting with a 16 pump because I always wanted one growing up. Probably just envious of my buddies who had pump 12's I guess. But, I'll take it with me a few times and see if I want to keep hunting with it or not. It'll make the cut or it won't.
