I shot alot of deer with RUM's and can't say I have ever seen this grinding thing you referr too. Mossy on here shot a small doe and no damage at all. Maybe you can help us understand what you mean?

You are aiming for the ribcage little low behind the shoulder, right? You don't want to shoot the hinds or shoulder. right?

I didn't like using the RUM for deer either, cause it was my moose gun, but had to get some blood on it before I took it to Canada.