I use two different brass catchers, both attach via an adapter/holder that is fixed to the pic rail of the upper. The first one I bought is the caldwell pic rail brass catcher, it works as intended but the ball detents on the adapter can slip a bit if you really fill it up, and although the mesh bag seems a bit low quality it hasn't ripped in thousands of rounds. The second one is from tacstar and it has a more secure and lower profile pic adapter mount and a thick fabric bag, it doesn't quite hold the same amount of empty brass but it works well and folds into a smaller package when storing and transporting.
I know you asked about free standing net type b.c., but I'd imagine the two I suggested would be much easier to deal with. I know they save me a lot of time and effort policing up my brass, and they work just as well for 22lr, 9mm, and .223/5.56.