It's a 54 caliber round ball
You will have to call TC to find out.
Frame
t/c contender serial number 308905
Contact Thompson Center Customer Service at 1-866-730-1614
You will need to contact Thompson Center Customer Service thru their website.
The Thompson Center Contender with serial number 1 80044 is a Generation 1 (G1) model. The G2 models began with serial numbers higher than 195,000.
The Thompson Contender with a serial number of 7000 was made in the year 1967. Thompson/Center Arms is a firearm company that is based in Rochester, New Hampshire
50-300 usd
You will have to call TC to find out.
No way to tell from just the serial number.
Thompson Center does not publish date ranges for there guns, but from the number I would estimate the date to be mid 90's