400
Seeing the Beretta was not widely used by the Allies in WWII, I would wager that it is now worth about 1300 dollars, strictly due to it's antiquity.
100-700 USD
Would need to know which specific model. "Silver Hawk" has been applied to several different series of Beretta shotgun.
Contact Beretta customer service thru their website. You will need the MODEL and type of gun. Beretta has been making handguns, shotguns, rifles and machine guns since the 1500s.
If NIB, with box, manual, never fired - it depends. Definitely in the 500-600 range. Maybe more or maybe less.
It all depends on the person that wants to buy it, the model (there are over half a dozen Beretta Stampede models), the the condition of the barrel and the weapon parts, the accessories that have been added to it and need of funds by the person selling it.
100-1000 usd
your Winchester model 1300 in unfired condition would be worth between 300-350 dollars.
I would suggest checking gunbroker.com or gunsamerica.com to get an idea of current asking prices. Asking prices & selling prices can be very different. As of May 2011 a Beretta Model 90 in 98+% conditions has been selling for $400-410 on gunbroker.com
About $700 if it is like-new condition.
If this rifle is in pristine condition,along with never being fired.A Winchester model 70 standard model would be worth 600 dollars.A Winchester model 70 deluxe(hand cut checkering,black ebony for arm tip) would be worth 700 dollars.