I think you should give it a try, K1 ammo is only bad on sniper, it's very good on standard weapons. Plus the red fury ammo type is a bit redundant with assisted fire - K1 allows you to benefit from both ammo type. And since you're in a fireteam, B4 or B5 does not make that much of a difference. Of course, if your meta only rely on ARM 0/1 troops, K1 won't have any significant advantage. But if you encounter HI from times to times, i think it's a good weapon.