The best way to determine actual value is to search the on-line auctions, such as www.gunbroker.com and www.auctionarms.com or even www.proxibid.com enter your details in the search and see what is selling and for how much. You can also search the archives and or sold items to get an idea of what your gun is selling for. Another place to look is The blue book of modern black powder values, available from www.midwayusa.com and www.bluebookpublications.com as well as many of the other hunting and firearm stores. Also available to NRA members on - line for free at www.nragive.org That will give you an idea of the general value. Guns tend to have some regional value too, say a Thompson Center Seneca may be worth a bit more in the north east than in the mid west, and a Ruger old army may sell higher in the northwest than the east coast. Don't forget condition has allot to do with value, and with black powder the bore is king. You may have a gun worth for example $500, but the same gun with a bad or rusted bore may only be worth $150 so compare apples to apples.
22-72
depending on condition $150 - $250
a32 caliber black power connecticut a thousand dollar
fill it all the way up get 1000 fps no worry about blowing up
$850-$1,995
50-300 USD or so
1200
10-100 usd
$100
50-150
Chances are that if you overload the charge in a revolver style black powder pistol, you can blow up the cylinder or blow the barrel off the end of the gun.
Impossible to value a weapon with just the caliber and serial number to any degree of accuracy.