I have a Bushmaster AR15 have flat top,  mount I have now for aimpoint compml2 is to low need some kind of riser any suggestions?

What type of mount is it? Post pics.

I've got a KAC 30mm Aimpoint mount -NIW and Box- that I'm looking to get rid of for well under $100.  Just traded my Aimpoint for an Eotech...

Graywolf...allow me to assume your current AP mount is not any type of cantilevered mount that raises the AP unit much above the receiver.  And, that what you now see when looking through the AP is lots of front sight and not much else.

If this is the case, your assessment is correct in needing to raise the AP above the integral rail on your Bushy flat top.  (I have the BM XM15E2S, myself...)  

I recently purchased a GG&G scout rail to mount on my receiver, in hopes of being able to co-witness my fixed front sight and GG&G MAD flip-up, rear BUIS in the bottom third of the sight picture when looking through my new AP.  Well...sadly, since the mount for my AP is the GG&G Cantilevered mount, the addition of the scout rail in combination with the cantilevered mount is too much height and I'm not able to use the scout rail, now.  (Want to keep the cantilevered AP mount...don't need the scout rail.)

I believe, if your AP mount does not raise your AP high enough, that the scout rail I no longer need would be perfect for your purposes.  Please IM me if you'd like to discuss this further.  I'd make you a heck of a deal on it.  

Best regards,
Bailagent100

If his Aimpoint mount is the stock low ring, then yes, your GG&G fire rail or whatever they call it will probablyl work well- just like having one of the ARMS forends...

QRP needs a 11.00 riser?