Mick,
Rifle A850 is recorded as having a completion date of 6th August 1971, on completion it was shipped to store at Donnington.
Rifle A1025 is recorded as having a completion date of 16th June 1972, on completion it was shipped to store at Donnington.
The highest serial number for the L39A1 in the records is 1287.
Cheers,
Simon.