M4 extend outer barrel with stock inner barrel (good or bad)?

[Goncikas]

Does it not gonna affect accuracy or other things if i going to extend my outer barrel on M4 without getting longer inner barrel?
And n00bish question too what's the length and diameter of inner barrel of stock King Arms M4 High Grade ?

[Ben_Manixom]

Re: M4 extend outer barrel with stock inner barrel (good or bad)?

Extending the outer barrel shouldnt make any difference to the performance of your aeg