Carbine GRT-BC damage inconsistent

Hi. The damage on the loadout menu is 25 yet when I test it in the shooting range it’s 21 and in game it takes 5 bullets bullets to kill the target and at over 20 meters it drops to 18 damage over 30 to 17 damage. Isn’t that too low for a carbine? Just saying because like what I said the damage is not consistent on the loadout screen. Thank you.