Assuming you mean a rifle in caliber .303 British, and not the ammo- depends on which rifle, and its condition. A SMLE (#1 Mk 3) or a #4 Mk 1 may be worth $100 for a poor condition rifle, or $350-400 for an excellent one. The TRUE Jungle carbines have their own values (many counterfeit copies) and other models different values. Rifles that have been "sporterized"- converted from standard military configuration are worth much less.
i have a mk 2 303 british with the org. cleaning kit and would like to know the value my email is rmelvin19632005@yahoo.com
50-300 or so
Value can range from less than 100 to more than 1000 USD
125 USD
125 USD
Approx $25 for the mag., and $10 for the cartridges
50-150 or so
50-250
100-1000 USD depending on specifics
100-1000 depending on exactly what you have, accessories, etc..
50-500 USD depending on condition, variation, accessories, etc..
50-150 USD or so