we open bolt kits
 

i see that TA has both the standard and CQB open bolt kits with only the standard M4 length version in stock.

I need this kit however i have the CQB version of the M4.

Is the only difference in those two open bolt kits the inner barrel length? I don't mind gaining some inner barrel length if i go the standard kit option.. are there any other differences in the two kits besides the barrel length?

Its just the inner barrel length, you already have the CQB inner barrel so you don't need a new one unless its a tight bore--which you should be upgrading anyways!

Airsoftparts has them too IIRC, to lazy to check their site, you can do it though to confirm for yourswelf.

Airsoft parts was OOS for the open bolt kit
Checked last Friday