a airsoft m203?

[A-98]

i need help designing a sort of m203 for my gun. it would basically be a small barrel sealing coaxial mounted under the gun. i have had a multi barreled design, but it had the out put of an asmatic smokers lung.

i also had a single barrel design but i havent had time to put it into ggdt.

pretty much the only spec is that it be <2" in diameter and not ludicrously long.

also i had an idea for a kind of artillary but with a 36" chamber th barrel would have to have been 15" long? that make little sense. it was going to be a over/under designt with a 36" by 4" chamber and a 40"by2" barrel. it also got a lame ass 111 fps in ggdt. could some one help me out


oh im going to be away from town for 5 weeks with intermittent access to the internet but none for 8 days starting today.


thanks alot