Someone probably did an 'oops' with their BPS in the field- I'd guess mud in the muzzle- and recovered it as gracefully as possible by shortening the barrel. Reinstalling choke tubes was a good touch- but the gun isn't a bargain at $350 IMHO. Nice gun, but not 'a real deal.'
A while back I ran across a BPS Upland in 12 gauge at one of my favorite dealers' establishments. Decent shape- some honest wear and dings, but no rust or evidence of mistreatment, 22" VR barrel with choke tubes, and a nice straight English style stock (see pic at http://www.rrarms.com/catalog.php?prod=G012216307
$275 out the door. It came home with me- neat gun.