Square peg in a round hole - KAK Shockwave 2.0 Blade Stabilizer Brace w/Buffer Tube

The stabilizer does not work with the included buffer tube! The locking peg on the blade is a rectangular shape that is too long for the female holes in the buffer tube. It slides forward like a ratchet but you can't lock it in any of the adjustment indentations. In the 5 minutes I've been messing with it, I can see the wear on the buffer tube indents where the locking peg is slightly too big to fit in the hole. If Opticsplanet doesn't play ball, I'll have to file down the locking peg. I'm not eager to do that because I don't want the crooks at the ATF to be able to say I "modified" the brace. Not what I signed up for. I'm guessing they made it tighter to try to address the complaints about it being wobbly, but apparently now the tolerance is tighter than they can manufacture consistently. I don't expect something rock-solid at this price point, but I do expect it to work. I also tried it on a well worn-in buffer tube I have around and it doesn't fit that either.