Being a 5 digit serial number puts it early in production , most likely early 80's. However the Hawken was not produced by Thompson Center in .36 caliber, they did make a drop in replacement barrel in .36, but they are very rare. I suspect you may have the Seneca model, this you can determine by measuring across the barrel, flat side to flat side. The Seneca will measure 13/16" across the flats. A Hawken will measure 15/16". The Seneca also has a patch box that is rounded towards the but vs. the Hawken being pointed towards the but. If it is a Seneca .36 in 95% + condition it could be worth in the $500 to 700 range, the Hawken with the .36 drop in barrel would be in the neighborhood of 450 +/-
You will have to call TC to find out.
It's a 54 caliber round ball
On 90% of the guns it is stamped on the right side of the barrel as "Thompson/Center Rochester New Hampshire" and "HAWKEN 45 Cal" along with a serial number on the left side. If not the easiest way would be to go to gunbroker.com or Google and search for Thompson center hawken, compare the pictures and description to what you have.
The Thompson Center Hawken rifle with serial number 66841 was likely made in the late 1970s to early 1980s. Thompson Center Arms began production of the Hawken model in the mid-1970s, and serial numbers from that era can help narrow down the specific year of manufacture. For an exact year, consulting a Thompson Center production records or reference guide would provide definitive information.
In a TCA, if it has letter preceding the serial number, it was made after 1971.
No way to tell from just the serial number.
The Thompson Center Hawken rifles were produced from the late 1960s through the 1980s, with serial numbers indicating their production date. Serial number 19889 suggests it was likely manufactured in the early 1970s, as earlier models typically have lower serial numbers. However, for the exact year, consulting Thompson Center's manufacturing records or specific serial number charts would be necessary.
Roughly between 41 B.C. - 2012 A.D.
You can download manuals from the Thompson Center website listed here in the related links, you can also find a phone number there to request a hard copy. You will need to know the model. In this case the 25th anniversary Hawken, same specs apply as the standard Hawkens rifle.
TC guns don't have a model number printed on the gun per say, they have a model name (ie Hawken Renegade Triumph Tree Hawk etc.) There is a corresponding model number in the catalog 9503 is the Hawken caplock for instance, but if you need to identify your gun go to the online auctions like gunbroker or auction arms and compare your gun to the photos there.
100-325 USD
The Hawken's are greatly undervalued now due to the new in-line guns and slump in the mountain man and rendezvous events, They are a very well made and accurate gun and USA made, depending on condition and caliber they sell in the 100 to 350 +/- range, with kit guns (serial # preceded with a "K") and .45 caliber in the low end and flintlocks and .54 caliber bringing the high dollar. A .50 caliber caplock in 90% condition generally sells in the 200 range. Retail on a new in the box presses the $600 mark As for when it was built, there is no published date codes but the number would put it in the early to mid 90's