I still own and (once in a while hunt with) a Bansner custom 1187.. the barrel has a .640ish choke of stainless steel permanently fixed into the barrel..circa 1988 or so. Cutting edge technology at the time.
I have killed a bunch of birds with it over the years.. I believe he called it the "Predator" choke system..
Bansner is an excellent gunsmith..