All my four different optics are all QD both from using ARM’s #63 mounts or such as Vortex holo sight and there 6x flip magnifier have interior QD bases. The top-rail really should protect the length of the top on the receiver and handguard, in other words, a free-floating barrel. https://cashjetfk.luwebs.com/32295121/5-simple-techniques-for-ak4d-slot