1969; this source doesn’t mention the grade. http://www.nramuseum.org/media/940941/serialization-date of manufacture.pdf
Yes, there it is on page 2361. Rudolph31, your source is better than the one on Browning's website which stated that I should have only a single digit after the letter "M." Thank you for sharing your knowledge.
You’re welcome. The Browning website is totally screwed up. I can understand for guns that go back 100 years, but there’s no excuse for stuff made after WWII.