I tried the velcro attached units many years ago. They're better than nothing most times, but still a PITA.
Next, I tried the Caldwell unit with the rail attachment. It works pretty well, but I found it impossible to use with one-piece cantilever rail scope mounts. This led me to use Warne QD steel rings, the highest they offer. They seem to be pretty solid rings but I'm not so sure about repeatability---I haven't experimented to see just how good (or bad) they are, but I was able to install the rail attachment easily enough and bought one for each AR I owned at the time. Like others, I found that hot brass melts the fabric and I eventually ended up with holes that allowed brass to escape. I acquired another AR and bought another complete setup and just used the new bag, but it suffered the same fate. I patched the holes with duct tape applied inside and out, but that was not a good permanent solution.
I then learned of the Lyman Tac Star brass catcher and bought two and also extra rail mounts. The Tac Star is more or less immune to the melting issue, apparently, but it's not perfect. The bag does not have a wire frame to keep the bag fully open, but it works okay while hunting if you are mindful that you can spill your brass.
So now the Brass Goat appears. I've got one on order and I hope I like it as much as the rest of you guys do. We'll see. I just wish I'd known about this a long time ago because I'd only have needed one to begin with, and it appears to be a just about perfect solution. I HATE losing brass!!
