That looks to "hang down" pretty far...
OP, check out curtiscustom.com, he has some AI style Mags (3rd) that fit VERY near flush with the DBM. Something like the APA dbm that has release built around trigger guard would be the ticket! However, not sure if he has anything in 223 (the 3rd mentioned is for 308 style, but it's only a phone call away).