Anything Valken is utter garbage.
Go for Madbull, BBastards, Elite Forces, Bioval.
Could also be your mags, but change up your bbs, I would use those valkens as paper weight, or use them in grenades.
They come from the same factory as Madbull IIRC, but they skip several steps,
Let's say for example there's "14 steps" to making quality bb's like madbull, and they do 13/14 steps, Valken does like 3/14 of those steps.