revelation 12 ga magazine extension
 

I have a semi auto 12 ga, revelation brand shotgun that is stamped ( brescis italy, )(thats exactly how stamped not a misprint)
that has performed flawlessly for over 20 years, that shotgun is one of my favorite guns and I would love to add a 2 or 3 shot ,
12 ga magazine extension to,
I don,t know who sells any extension or what other brand of magazine extension might be interchangeable,, thus that might be used?this appears to be a very well designed inertia driven action, similar to Benelli or H&K
any help would be appreciated

maybe add some measurement ( inside outside ) of the tube and maybe there will be some that have other makes models that can compare spc's too
most common to add longer tubes will be rem 870-11/87
mossberg 500's
I don't know spec's off hand on them but places like Mid way and such that sell them might have spec's listed on web site to see if they match up for you, if not they will have the OEM of the brands they sell and I gather the makers web sites should have spec's or can be emailed and asked for them!
to see if you can convert one to work for you!
Briely Choke tube maker( https://www.briley.com/c-240-choke-tubes.aspx ) is famous for making and adding screw in chokes for shotguns, I would expect they have the means to MAKE you a tube extension, might end up having to ship them your shotgun, so they can thread your gun and match up a tube for what ever spec's you need to have an extension made
springs can be had again from other tube extensions for other guns I would imagine, same gauge would be close enough to work on all like gauge guns, as long as you get lengths right, springs should work IMO

just some idea's off the top of my head for you to think on?

thank you, Ill try and measure the threaded area on the end of the shell feed tube

what model is it?