You'd generally run 0.4g+ in a sniper, but you should be able to turn the hop down to accommodate anything. From what I'm seeing, it has two grub screws to adjust the hop, under the mag - are you adjusting both, and have you tried going all the way in both directions?
Thanks for the reply. Yes I am adjusting both and using .32 bbs at the minute. I'll try adjusting both out and go from there I'll have to purchase some .40s in the future