It is compatible with standard AR-15 magazines, so if you are using magazines that use the same dimensional specifications as a standard AR magazine then yes.
Yes. I use mine with 6.5 Grendel and ASC metal mags. Also works with P-mags when I switch uppers to 5.56 or 300blk. It is great for hunting because I can keep the mag with the rifle and is considered not loaded for transport.
I use it all the time with a grendel mag. Works just fine.