Here's a better look at the top of my receiver:



My s/n is F757XX, and according to Gene M. it's not known the significance of the letter "F" in front of the s/n; about 75% of the observed s/n's above 75650 have it, he says, but there are no discernible differences between a sporter with or without the letter preceding the s/n.

Based on your s/n your sporter *should* be an '03 model, which would mesh nicely with Gene's research that indicates Remington introduced the .303 Britishicon caliber to the M1899 sporter lineup in '02.

Best,
Garrison