How many people wondering this haven't been really paying close attention to the show? Maybe just catching a episode here & there?
Just since Woodberry was introduced they went out & took down a small Nation Guard unit. There was guns & ammo to be had in that attack. Then there was mention of that not being the first time he had gone on "supply runs" like that. When there is no Police, no store owners, no guards, ect. It would be easy to get access to guns & ammo of all kinds if you looked in the right places. Not to mention finding them in places where armed people got over-ran by walkers & eaten. Now I'm not saying guns would be littering the streets, but they would be available in many places.
Yes, because full auto mp5k's,ak-47's,browning 1919's, AICS weapons chassis and the such would all be so easy to find. I've watched the show, i know the background. I think it's also ridiculous that every ar they found in the prison is full auto as well. I just think they take a little to much liberty with the show on the technical side of it. It's not DayZ after all.