Winston,
I see you just joined the board so welcome! From your description you have a Grade 3 Hollenbeck. The 12 Ga was the most common shotgun guage while from most records the 32-40 was the most common rifle caliber configured with the 12 ga barrels. The 30-30 was also common on the 12 guage guns as well. I am traveling for work and won't be back to my office until later this week. I can see if I can find any info on your serial number.
Condition will determine the value of your gun. How much original finish is on the barrels, how much case color is remaining on the frame, is the wood finish original or has it been refinished. What is the condition of the rifle barrel rifling? Feel free to PM with your contact information and I can reach out to you when I am back home later this week or weekend.
