I sold one to another member a few months ago. I used it and would not recommend using anything else. I used it after someone else used a modified open end wrench and bubba'd it up.
Menck retired years ago and hasn't made anymore wrenches since then. I doubt Brownells will be getting some ever again from him. LPR Gunsmithing has one that he won't sell but will perform repairs.
Hard to believe they are not available There are jillion of those rifles out there Does no one take them apart for cleaning? Brownells, Midway, et al have none, -- strange
The one I took apart had 30+ years of copper and carbon build up in the barrel. I chucked it up in a vice and cleaned it for two days. The owner and I shot it yesterday. Surprisingly it would keep a 3/4" group at 50yds and 1.5" at 100yds. He's happy as a lark. So I would probably say, no, they don't get cleaned properly.
I'd bet 99% get cleaned from the muzzle or a bore snake, some cleaner lube sprayed in the chamber and doodled out with a piece of old T-shirt cutoff into a patch!!