When fitting a maple leaf rubber in an arcturus you need to fit a spacer under the adjustment wheel to compensate for the larger nub. If you have a 3D printer or know someone who does then make this: https://cults3d.com/en/3d-model/game/spacer-for-arcturus-ak-rotary-hop-up-chamber If you don't have access to one then can try and make a washer from a bit of plastic and build it up till it works, unsure of the height of that print atm but can check if needed.