make sure that the four grub screws are actually tapped all the way through. mine had a grub screw that was not tapped through and thus was not extending far enough into the D opening to actually grip the hanger. Just remove the D ring and try screwing all grub screws as far in as they can. I bet you’ll find that one of the screws does not protrude far enough into the D.
Only use 2 adjacent grub screws to pin the hanger against the other side of the D. Make sure the opposite two grub screws are completely out of the way when you pin the hanger. Only once the initial two grub screws are locked in, you can tighten the opposite side’s grub screws.
I tried all of this i think, when i just got it i followed their guide on how to mount it and it was really solid i could hammer it and it would say on there.
But after the ride the screws ate into the metal almost and made it loose again.
The grub screws will inset about 1mm into the hanger. That is not a big deal.
Are you sure you tested out to make sure the grub screws are tapped all the way through the D ring? I have 3 mounts right now and all of them have 1 grub screw hole that is messed up.
After realizing this, my mounts have not moved since. I use blue loctite.
The pot aluminum used on those caiber 2 hangers is too soft. Even if you do get it tight with four grub screws, as soon as the metal deforms everything will be loose again. I’m not trying to promote my mounts, but it’s why I stopped making mounts for caliber. You guys can keep battling the shit fit of caliber clamps or just realize it’s a lost cause.