Well for starters the ones at the front are probably not freelance the same as you. They are contarcated to NME, newspapers, the actual music industry etc.
With local events some may also have a press pass for whatever local rag they work for.
The only way a truly independent photographer would get to the front is via invitation only. But who will you sell the snaps to when there are contracted photographers there?
Put the feelers around, get a portfolio and send to as many publications as possible. Get a name for yourself, get an invitation and bob's your uncle.
Otherwise just be a paparazzi which is a free for all.