I was stationed at Tinker in 99, I found out about Mark through Tom (the guy who sells AR15, AK47 and L1A1 parts at the OKC gunshows).
I was told he is a good guy to deal with.
I went in his shop twice, once to buy some ammo and about laughed my ass out of his shop after seeing the prices on his Wolf .223 ammo. Then I looked at his M16 mags and saw a postban mag (marked) for $50. Then I saw the FrankenAr15 on the shelf, it was a postban (since I had the list off of AR15.com) and verified it was a postban.
The next time I went to his shop was in 2000, I had a preban Oly AR15 with a 100% Colt M4 upper on it, I asked him if he would put it on consignment or if he wanted to buy it outright.
He told me he would buy it for $600 and that he would not put it on consignment.
I was thinking that $900 was a better price for the Oly/Colt, and if he wanted to keep putting junky and rusted guns on his shelf then more power to him.
OAS had better prices, but not by much.
I wasen't looking for him to hand me the key to his shop and bend over to take it dry, I was expecting that he would have wanted to make a sale. In the time I lived in OKC WalMart, Eric the Ammoman and some guy who sold ammo at the OKC gun shows got my money for ammo.
I bought all of my firearms in OK either at the OKC or Tulsa gun shows.
That was in 2000, when he was complaining about not breaking even perhaps he figured it out that you can't screw customers.
He said it best when I asked for a better price on ammo "If you can buy it cheaper on line or at the gun shows then do it".
So I did.