Not to advertise, but I make them from Delrin on my lathe for $45 shipped. I would need to know barrel OD - " or MM. Usually just pound on with a dead-blow hammer - no attaching screws or dovetail, front sight filing.
I like the slimmer one I made. And it does not add any length to the 124's looong barrel. Doesn't look like a big schnoz on the end. Takes me a fair amount of work to make one, though. Don't I get a great finish on mild steel with HSS? Not polished. Not necessary.
are you looking for a weight or a break ? You list Break in your title but then picture weights after that ? Muzzle brake redirects gasses at the muzzle to pull or push .
Are there enough compressed gasses to make any muzzle brake effective in any air gun. I can tell a small and I mean small difference in a couple of my big bench type AR 15 rifles chambered for 6.5 Grendel, but those rifles are something like 13-14 lbs so weight helps a lot also and it is a small cartridge.
I think a muzzle break on an air gun is more of a last thing air stripper than on a powder burner that redirects the gases to lessen barrel flip . Air gun usage is to strip the residual air from pushing a pellet after it leaves the crown .
Thats my opinion, I had put one on my rifle about 40 years ago and took it off last years to put a front globe sight back on to use with a diopter sight.