Ya know, you are right! Today I pulled real hard and sure enough it cocked. When it ran into metal the first few times I cocked it I thought it was all the way back, but no. Pull real hard past that and it cocks.But it still leaks even when cocked. So a seal job is in order. Might be a winter project. However, Tom Gaylord wrote a 2 part piece on the Blue Streak and several items in there made me question whether or not I still want to bother with it. https://www.pyramydair.com/blog/2019/07/sheridan-blue-streak-part-1-2/1) You have to pump up to 8 times for each shot. Whether or not that's interesting to you is something each person has to decide. 2) Not as accurate as an RWS 34 and I have one of those that was professionally tuned by a tuner on GTA. So....a marginally accurate rifle that you have to pump a bunch of times for each pellet........hmmm...I'll think about it.
I think you'll find the stamp is actually "5691G" - to be read from right to left (i.e., backward) this is G for for 7th month of 1965. This format was used from '64 to '72.Don R.
1964 - Two changes Inspection dates now stamped (backwards and alphabetically) on the left side of the receiver. (Jan 1964 - Apr 1972) Front sight changed to a large forward serrated ramp style 1964 - 1977)1965 - No changes1966 - No changes1967 - One change Trigger guard now attached by two rivets1968 - Two change Grooves removed from the Receiver (now smooth flattop receiver). (Mar 1968 - Feb 1978) Curved bolt handle now welded to bolt.1969 - No changes1970 - No changes1971 - Two changes Left-handed version introduced (Jul 1971) ( Approx 400 made) Rear sight now clip-on attachment. (April 1971)1972 - Two changes Stamped Serial numbers introduced ( 000001 - 025650). (Apr 1972) Hole in bolt handle made shallow (19721974)1973 - No changes. Serial numbers ( 025651 - 060550)1974 - No changes. Serial numbers ( 060551 - 100780)1975 - One change. Serial numbers ( 100780 - 141460) Hole in bolt handle eliminated.1976 - No changes. Serial numbers ( 141461 - 175840)
Since you don't have anything to lose,, put some in both places.
I sure wish we could edit our posts!! Anyway, click on the image and you'll see it pretty clearly.