Yup. The Magnetospeeds cause a POI shift, so you cannot zero your optic with the bayonet mounted. Pretty sure it’s even in the instructions, but it’s very well communicated among us shooters. The extent of the POI shift varies by rifle and arrangement. On my Seekins Havak, with a SiCo ASR brake I get about .7mil high and .3mil left. With the SiCo Omega out front (not using the ASR brake, but direct thread) I only shift .1 left and .2 down.