Others have already suggested a class change for the current ammo to better reflect it's real life counter part.
I've also heard the developers talk about trying to keep a game balance for weapons.
So I think the following would be able to better reflect its real life counter part and manage to keep somewhat of a game balance. It would be pretty close to the Solokhin being able to reach one more class yet, you have to change ammo to get it's full range.
Change the current ammo to a 4-7
add a new varmint round (2-4) for the 6.5mm