I had some issues with the Krink-style brake that I ordered. I finally did get it to work on my rifle, but not without much cursing and Dremel work.
First, I tried threading the adapter into the brake. It stopped about 1/4 of the way in and I removed it. At that point I threaded the adapter onto the muzzle and then attached the brake to the adapter. Still, I encountered resistance about 1/4 of the way on. Using vise grips, I managed to get it threaded on (yes, I checked to make sure it wasn't cross threaded).
However, the notch in the brake did not line up perfectly with one of the four notches in the brake. The brake appears to have to be threaded onto the adapter completely to minimize interruption by the front sight base pin when attaching the device.
What I ended up doing was widening the notch on the brake to coincide with the notch on the adapter and then soldering closed the extra notches. I then dremeled the soldered parts down. It attaches fine now.
I mention all of this because it seemed like a hassle to install the thing. Perhaps I did it wrong, but I am unsure as no instructions were included. You might want to include instructions or specifically mention "some gunsmithing may be required".
Also, the AR Birdcage style AK flash hider also didn't thread smoothly onto my rifle either (although I did finally get it on and without the drama I had with the Krink brake above). The AK-74 style brake I ordered attached smoothly and quickly and so does the stock slant brake. The rifle is a WASR 10/63 I purchased "new" in Spring 2007.
I'm otherwise happy with the order and look forward to ordering from AIM again.
(And yes, one of these days I plan on dragging all of those devices to the range to see how they compare.)