I picked up a Brass Goat, seems to fit all my ARs just fine. 5.56, .300bo, 7.62x39, 5.45x39, 6.5Grendel.
I also run a shell deflector on my 5.45x39 AR. The Brass Goat without the collection box does a better job as a deflector.
I also have another brass catcher that’s a cloth bag with a snap close bottom. Works well enough but requires a mount that bolts to the pic rail. So to run it on multiple ARs, it’s $17 a pop for more mounts.
only downside to the Brass Goat is you can’t do a mag change with the right hand, only from the left. And my cloth bag brass catcher works with my Magpul D-60 drum.