I'm wondering...
Why not introduce a lower-tier hunting rifle using different ammunition, and retain the .223 version as well?
If I recall correctly (that'll be a first), the ammo modifier alone would change their effectiveness without need for modification of the weapons.
I realize the devs stated that they do not wish to introduce new weapons, but I'm not sure this rule applies to this particular situation.
More options to suit whatever requirements somebody has.
Not really any personal preference (hell, I still run around with a 10mm and have problems getting caps to feed ammo for that

), just an option I noticed nobody mention.