Yes- so what is the problem? I have a shotgun I have had for over 60 years. You need to be a bit more specific here.
no when your shooting at something you will never tell
yes
Yes, they can live for 20 or more years after being infected.
Highly unlikely you will find any. Getting them made will probably cost more than the shotgun is worth.
At least 20 years.
20
... are unenforceable... There are some patents that expire in less than 20 years and some that expire in more than 20 years, depending upon what you're trying to ask.
Either one can have more than the other depending on the load and total weight of the weapon.
It would depend on the load you were using, but generally no, a 20 ga would "kick" more
More than 20 years
Uranus.
no, 20 is about the maximum.