KA M4A1 + M203 - some questions
 

I'm considering a barrel mounted M203 for my King Arms M4. As of today, the battery is still in the handguard. I've done some preliminary research and have a few questions.

1. Is it possible to keep a 9.6v nunchuck in the upper handguard that remains?
2. What options are there to replace the upper handguard that will eliminate the gap where you can see part of the outer barrel? I've seen the G&P upper handguard replacement and I'm not crazy about it. I'd prefer something that looks and flows similar to the stock handguard. I'm thinking upper portion of RIS with rail covers? Any recomendations?
3. Which barrel mounted M203s are recommended? I see the Echo1 pop up in most shops. Is that one decent or is there another one I should be looking at?
4. Not critical, but an estimate how much this endeavor might cost?

Any insight or personal experiences appreciated.

if it'll put just move the battery to a battery box on the side or top of the rifle.

if you do RIS you should have no problem with mounting it, not to sure on the rest as I'm kinda new to airsoft and not even considering an m203 yet

DBoys M203 is a very good piece for the price. Look up the review on ASC.

Rear-wire the mechbox to a battery in the stock/buffer tube?