Hard to understand what rails you're describing. Can you post some pictures?
What I "exactly think" is that KelTec never engineered that particular stress-load into the specs of that rifle (meaning just the increased WEIGHT). That's not counting the shock-load of the 16 gauge recoil. Responsible firearms manufacturers have staffs of well-educated, experienced engineers, rooms of AutoCad stations, and safe facilities to destructive-test their concepts all the way to...KaBoom!So what exactly do you think would happen if I tried it? I'll admit the more I think about it the idea just sounds worse & worse. It would probably be twice as heavy as the rifle itself.