Here's an issue I have had with Sevr, I think I have shown pics before, but maybe not.
Deployed correctly:
View attachment 767518
Notice how much of the blade edge is either congruent or behind the deployment tabs? 1/3 of that blade area is covered by the tab, means it's not cutting its way through. That's a 2.1, I have switched most of them to the 2.0 blades, which are a little better, but still have the same issue, a knife isn't going to cut well with a dull edge stacked right next to it.
Here's how I have found the heads twice:
View attachment 767520
Blades will lock in that position, it does away with the issue of a tab covering the blades, but that's a horrible blade angle to try to push through an animal. I can't be certain that's how they passed through, and they did, I found both arrows just laying on top of grass behind where the deer was, but I'm used to them being buried in the dirt, not just laying there. Could be the fletching makes enough drag on the way out to allow the blades to push further forward than they would initially, but I could also believe those tabs could leverage the sharp ends out past where they are supposed to be.
The smaller cut versions seem better, but I'm not much on using a mech head that's almost cutting what I can get with a fixed head. I want a bigger cut, mainly why I use them, they can be more forgiving, but I haven't had penetration issues with most mech heads and would prefer to maximize my wound channel.