Yeah it's baffling for me at first that M7 deals the same damage as M4A1, but M7 has way longer(maybe infinite, can't remember) 4 shot kill range from what I've read, where as M4A1's damage range drop off quick. It's a OK trade-off I guess, but it's still a bit jarring to me that HK417 and M7 are both "carbine" in this game and the M7 deals 5.56 damage. Not the end of the world for me personally, tho.
Bullet velocity wise, I think one needs to take a look at bullet velocity for all weapons in the game as a whole, which admittedly I never really looked into, to decide if the the muzzle velocity is fitting for a weapon in the game. BF MV always tends to be on the slow side of things, the current situation is already way better than what was in BF3/BF4, which had like airsoft ballistics.