Don't know if this is the right area to post this but I just ordered and received some American football shaped ice moulds after seeing primal sling's concrete ammo video.
This mould can be used for ice or concrete. In my opinion it's the perfect shape and size for ammo.
They spin in flight and don't curve as much compared to other ammo.
Also really cheap too.
https://amzn.asia/d/hZEcnju