Milsurp After Hours

i picked this little jewel up from a guy whom spent 30 years in the US Army from Vietnam to present day. he didn't know what it was nor where he had procured it, but was pretty sure it had some Czech in it. single shot, smooth bore with sight groove in front receiver. looks like it should be a shotgun except for the thickness of barrel and cannot for the life of me figure out the caliber or gauge. has a 26 stamp on barrel and stock next to each other. So, what is it?

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http://i5.photobucket.com/albums/y178/l ... 0_0110.jpg[/pic]

What is the bore diameter?

Is it center-fire,rimmed or rimless appearing?

John

i think I have narrowed it down to a 9mm Rimfire shotshell. i forgot to mention the bolt being rimfire. there is no telling who made it and when.