We actually do a lot of penetration testing on a variety of different media all the time. It's a big part of the design process for some of our products and there is a lot more testing that goes on that we do not release to the public.
In this case however, we actually did quite a few tests to this effect inspired by the show. Lynn and some of the PROOF crew are big fans of the show and they wanted to try it for themselves
We have used Pig and Cow skulls as well as other testing media. Some of which we filmed in an impromptu test outside our warehouse a few years ago (you can find the video on our Official Facebook Fan Page) and some of it may appear in our new PROOF video which will be released early next year
We found that we could indeed pierce even a super thick pig skull with our folding knives without compromising the integrity of the lock or damaging the tip of the knife but the penetration varied on the knife / angle etc...
The tantos did very well
With larger fixed blades we had even more success (a Laredo Bowie actually split the skull length ways as well!)
We also tested a variety of "Specialty Items" such as the SF Shovel and a selection of hawks
The over all winner by a long margin was the Spike Hawk which not only effortlessly penetrated deep into the skull, but it also was incredibly easy and fast to extract and get back into play.
One of the advantages to having daily on-site testing and an experienced crew is that we can watch a TV show and be inspired to try something and then almost immediately go out and test it.
It was a little gruesome, but very interesting
That's one thing about our HQ, it's never boring