I'm intentionally dropping the mm and NATO for my suggestion.

NATO weapons chambered in 7.62x51mm NATO are simply labeled 7.62. This causes unnecessary confusion for playes that don't know it actually means 7.62x51mm NATO when they are trying to pick up rifles or ammo from Syndikat fighters armed with 7.62x39 AK47/AKM/RPK or a PSL/SVD/RPD in 7.62x54R or a Tokarev in 7.62x25.

If you include bullet diameter and case length with all cartridges and weapons (unless not commonly used - .30 Carbine (7.62x33mm)), you will avoid other issues of similar bullet but different cases (9x19 (Parabellum/Luger) vs 9x18 (Makarov)).