15 I X date at 15-02-49

From the Kynioch box code key , the first letter denotes the month the second the year and the number is the day

The red and yellow box was made from 1936

If the correct bullets are in the box the code for them is RNGMCStSN.which means

Round Nose Guilding Metal Covered Steel Soft Nose ( Magnetic )

charge was 52 grains of Nitro Celluloes powder
bullet weight 250 grains

Reference BRITISH SPORTING RIFLE CARTRIDGES by BILL FLEMING

I'll buy them of you

all the best
sbs470