thanks Ned, i'm hoping it's more likely a '98-'99 upgrade.  It's certainly not in the accepted serial number range for '98 carbines.

or perhaps one of the conversions prior to public sale. 

I am haven't fired it yet, the only ammo i have is the old leftover ammo that my father had. Some of which looks like it was reloaded.  the projectiles are newer styles, probably 180 grain, but in a casing that was originally loaded with the 220 rounded top.

thanks again.