Mark does have a great deal of experience and knowledge to share.
I received his book " Fear No Death" for my birthday this month and IMHO it is well written and illustrated. I have just reached the chapter on shooting a double rifle and hope to finish the book this week. While I am not up to hunting as hard as he, his adventures are interesting.
For what it is worth, I bought an ammo carrier much like his some years ago and wear it much the same. It works for my .405 WCF and .45-90 and I found myself checking each round before going into the field by pushing it up from the bottom - just common sense, I guess.