What i meand is the late reproof date, sure the rifle itself is much older. But for me it is interesting that it was proofed again in 1943, middle of ww2.
For my opinion it was used for hunting, not for use as trainingrifle ore rifle for the hunting type matches like "running boar", tipical this rifles were used with lead bullets. The "J" stamp says that something was changed, i think it was reborred to get the bore dia for copperjacket bullets.
An interesting question would be if there are any older proofmarks, also it is possible that an new barrel was used in 1943 with the old system.
These two points would give an meaning for me to use the J proofmark.

( sorry for my english......)