It has two barrels, side by side. Most call it a double barrel.
A model 1200 made by Browning is unknown. No such model exists. Winchester made a model 1200 Shotgun, perhaps that's what you are looking for.
That's not a Sweet Sixteen serial number. In fact, it doesn't even look like a Browning number to me.
Look on the receiver and barrel.
Check the receiver
Contact Browning or go to their site and look it up under Customer Service.
Go to Browning.com and look under customer service.
Some have gunsmiths on site. Look in the Yellow Pages.
left side of barrel usually
Requires a gunsmith to look at it.
The Browning website has a page enabling you to find your shotgun's age, but you have to know the type of shotgun you own. Go to the page, then click on the type of shotgun it is - there are 15 types - and then reading the page for that gun's serial numbers. Look for the series of serial numbers that includes the one you are interested in: #48162.
Value of a shotgun is driven by several factors. Condition, model, area of the country it is sold. Look at one of the used gun sites like gunbroker.com. Then compare.
Look at the serial number again as this is imcomplete. Go to Browning's site, Support, Date your firearm and they have a list of dates.