Wow only 100 $. Thats quite a good deal.

Read the OP, he's asking what it needs to be a CQB gun, it sounds like he already has an "outdoor gun". He's just too lazy to keep swapping springs every time he goes from outdoor to indoor and vice versa is what I understand when I read the OP.

not lazy just don`t want a mp5 when ive got a perfectly good thompson, the only reason i bought it was so i could use it for when i visit toronto area to play in arenas

I don't personally own one but my good buddy does and here is his thoughts on the gun:

I don't know if your having problems with it yet but the Hi-cap that comes with it is a pain. The mag eats the "ready" Bb's fast, might want to get different mags.

The stock can interfere with a full face mask when trying to look down the barrel. (or my buddy is just a huge man with a to scale head lol)