Maybe not too scientific, but I got a hairy bugger last night and decided to run sort of a test on his "shield". I started with .45 acp and worked my way down to .22 short.....everything went through without a problem. Granted the shield is just part of what a person needs to penetrate in that area to kill one...but the shield itself didn't offer much in the way of a problem to penetrate.
This hog went down with one shot from a .223 fmj through the neck with a frontal shot and it's head down eating.
http://s1353.photobucket.com/user/stony410/media/DSCN0910_zps52de0e80.jpg.html
http://s1353.photobucket.com/user/stony410/media/DSCN0901_zpsef6897e9.jpg.html
http://s1353.photobucket.com/user/stony410/media/DSCN0904_zps9ec0d015.jpg.html
http://s1353.photobucket.com/user/stony410/media/DSCN0905_zpse4ea4c40.jpg.html
This hog went down with one shot from a .223 fmj through the neck with a frontal shot and it's head down eating.
http://s1353.photobucket.com/user/stony410/media/DSCN0910_zps52de0e80.jpg.html
http://s1353.photobucket.com/user/stony410/media/DSCN0901_zpsef6897e9.jpg.html
http://s1353.photobucket.com/user/stony410/media/DSCN0904_zps9ec0d015.jpg.html
http://s1353.photobucket.com/user/stony410/media/DSCN0905_zpse4ea4c40.jpg.html