[frontlinesniper]

I'm not sure if its normal or if there's a problem, but whenever i fire my m4 it makes a loud thump after firing almost like a very hard release(kind of like its hitting metal sort of sound). The gun is stock so there's no upgrades. My bro's 552 is stock and very quiet compared to mine so thats why i was curious... I know its normal for a thump from the release of the spring obviously but it just seems louder than it should be.