Advel type 734 pneumatic rivet gun ?

[gm280]

Not sure this is the correct place (forum topic) to post this, but it does have to do with boat repair, so here goes. I have an old Avdel type 734 pneumatic riveting gun. It is presently set up with the 1/16" rivet nose attachment. And it works really good. However, what I got it for was the numerous 3/16" large faced rivets I will need to install on my boat project with the rub rail installation. Does anybody know or can tell me where I can find the 3/16" attachment for this gun? Thanks for any info...