Alot of birds have been killed without camo guns..... I didnt use one until about 5-6 seasons ago and killed plenty of birds without camo on my gun.
BUT the cost to get one camo dipped or by one already dipped is relatively small when (170$) when you consider it cost me 80$ in gas to fill my truck up when I want to go hunting...so to me, its worth the cost to give myself the extra advantage of having a camo gun in the woods.