You will have to contact Browning to find out.
1971
The BL22 was made from 1970-2003.I would contact Browning directly and their customer service dept can identify the year of manufacture for you.
50-400 usd
The serial number is not correct for a BL22. It should have letters associated within the number. Please re-check and ask again. Thank you
Can't be answered since no serial number was provided.
1971, up to 500 USD
Try the blue book of firearms value or call browning
Check the auction sites. To many variables that you don't address, like overall condition, accessories, box, manual, number of rounds fired, etc..
You may be able to find an instruction manual on eBay or Auctionarms.com
It was made in 1974. As with any firearm, it is not possible to accurately appraise a gun without seeing it. Condition, and original configuration will determine value. Other factors such as rarity of caliber or guage and higher grades have significant impact on value. Recommend that you see a local gun dealer for an appraisal. You can also do your own investigation by looking at other models being sold that are in the same condition as yours. Try the gunbroker.com or a periodical called "The Gun List" You can also reference the Blue Book of Gun Values which can be purchased on line at various retailers.
The answer is no. The BL22 was introduced in 1970 and had a "70B" preceding the production number. The number changed for each year thru 1976 which was 76B. After 1976 the new system was used and a two letter code was used to determine date. Be aware though, that FN produced and sold this model outside the US beginning in 1956. These were FN guns and essentially the same as the Brownings that were imported in 1970. The markings are different and do not say "Browning Arms Co." on the barrels. It's probable that the FN guns did not have a letter in the serial number.