Just got my BAD in and installed it on a DPMS lower with that I already have a KAC ambi mag release on. The part number for the KAC part is 20470-1 . I thought that someone at magpul had said the two would work together, but maybe there was a missunderstanding that the KAC lowers with ambi mag release built in where what was meant. The BAD almost fits into the dip in the KAC part, but it seems that the BAD ia about half its width too far forward towards the Magwell. The KAC part keeps the BAD from moving in towards the reciever so the bolt catch can't pivot at all.