Power issues

[nickw20]

I'm hoping someone will have an idea what is going on here. I have just test fired my ares am013 dmr build. For the first 5 or so shots it's firing at 1.77 joules as expected but then the next few shots are way up at nearly 2.3 joules. And then it will go back down to 1.77 ish and repeat the cycle. I'm not entirely sure what is going so any advice would be greatly appreciated.

[Cr0-Magnon]

You definitely haven't mixed your BB's?

[nickw20]

Yes as it turns out, never use a mysterious plastic bag full of bbs with a sticker saying 0.36g. It's a lie. Opened a fresh pack and it's firing perfectly. Thank you