mounting buis on CASV rail

[clayart]

I have the CASV piggy back rail system and need to know if there is any problem with mounting my sites on that CASV -vs- the visible rear part of the upper (there is a little bit of the upper that does not get covered by the CASV. I had the CASV flip up front site and a MI rear flip up. I have since purchased the new Magpul BUS and there is not enough room to mount on my upper. Should I just remove my front site and purchase the Magpul front site and place both front and rear on the CAS rail? Thanks.

[Uglyduck]

Do you have the CASV-EL or the M model? I'm assuming the M because you stated you have the CASV front sight but I want to be clear.

[clayart]

yes sir, I have the M.

[Uglyduck]

Got it, your sights need to be mounted on the same plane, albeit high over the bore