It is fairly common to have non-matching date codes. The letter "J" is not used for marking receivers; only parts. See link below.
The Symbols on HK Firearms
From text:
A B C D E F G H I K
0 1 2 3 4 5 6 7 8 9
The letter corresponds to the number. The letter 'J' is skipped for proofed firearms, but is present on magazines.
Best,
TC
The Symbols on HK Firearms
From text:
A B C D E F G H I K
0 1 2 3 4 5 6 7 8 9
The letter corresponds to the number. The letter 'J' is skipped for proofed firearms, but is present on magazines.
Best,
TC
