I am planning on buying a CMMG M4-style upper on my Colt Gov't. Carbine and I have one stupid question. Does the M203 cut out in the barrel affect accuracy in any way? I know a barrel vibrates when you shoot it and I want to know if the cut out affects these vibrations. I was just wondering how a 16" barrel without the cut out compares to one that does have it in terms of accuracy. I want an M4-style upper mainly because of the flattop upper receiver, but I also want a barrel heavier than the "pencil" barrel I have now.

why not just get a 16"" flattop bull barrel if your worried about accuracy....

and you wont have to worry about that barrel being to skinny........ you could also save weight by fluteing a bull barrel.......

i've had great accuracy from my bushmaster m4 barrel.  

No, it doesn't affect accuracy in any noticable way.

No it should't.