The backpresure wouldn't work anyways, it would just slow down the bolt on its way forward. It work in firearms because the bolt is already closed when the presure comes around and it is not creating the presure. Does that make sence? It should, but not everyone thinks like me or can read minds.
It was definitely meant to be played in a large park. I see your point about the BDU's. Now I am thinking that same color shirts or a handkerchief tied around your head would be better. In order to make the round less boring and long, you could have an "extraction time" and if team A doesn't meet the dead line, they loose. This game was never meant to be played with a whole ton of people. Originally, I thought 3-5 people would be best. It's not the kind of game that DCNO or other large wars would play. Just something else some friends can do.
Sorry, I wasn't sure if that thread was to encourage us to think of new ideas or to post new ideas there. I understand the BDU thing, I wear one as a light jacket though. I like the handkerchief around the head thing too. Supply of BDU's isn't a problem for me I have two and my friend has one. I will pick some more up over the summer and I never planned for my games to get to more than four or five people. Giving team A light guns, pistols and such, also discourages team A to shoot first.