No such thing as a 20 caliber shotgun. 20 gauge is the correct term. Blue Book of Gun Values will help. Actually, it can be called both. Especially, if the barrel has 20 Cal. etched on it.
value of a beretta model 413
100-400 USD
100-340 or so
AFAIK, Beretta has never made a handgun in that caliber.
50-260
200 or so
best condition 1000.00$
The Beretta AL series was made from 1969-1976. Value would be $250-$350.
50-400 usd
how much is a petro beretta 16 gauge in excellent condition worth
25-175 USD or so
nig it is 3000000000000