Yea not bad in terms of shape and details but you really need to work on the proportions of your weapons.
Look at these reference images to see what I mean. Yours looks kind of bubble like or semi distorted which is fine since it makes it look more cartoon like to me.
My biggest issue is that the stock is not lined up with the barrel which docent make sense. M4s & M16s have their recoil springs/pistons housed in the stock so yea it has to be line up Unless its built like and ZM LR-300 which uses a different system.