I have a CBC 20" upper with a rifle length gas tube that wont cycle. Im using carbine buffer tube and buffer. I have tried 3 different lowers and BCGs. Would it not cycle due to not having rifle length tube and buffer?

Carbine buffer and springs only work in carbine length receiver extensions (buffer tubes)

You cannot run a rifle length buffer and spring in a carbine extension tube

You should not run a carbine buffer and spring in a rifle length receiver extension

What type of buffer tube are you using ?

If you have tried that many lowers and can’t get it to cycle then:

Have you tried factory ammo with known sufficient power to cycle a BCG ?

Have you tried to realign the gas block, some need to be set off the shoulder by a few thousandths of an inch.

Worst and last case scenario would be to measure your gas port size and make sure it’s large enough for the gas system you’re running

Im using carbine buffer tube and carbine buffer. I do not see any markings on the buffers to be able to tell what weight they are. Yes I have tried different ammo 223 and 5.56. It will sometimes cycle 2 or 3 rounds and reset the trigger but fails to battery the next round

Rifle buffers weigh about 5.1oz... carbine buffers are 3oz, even an H2 carbine buffer only runs 4.6oz.

It sounds like you have a (not enough) gas issue. Mis-aligned gas block, bent gas tube, too small port on barrel, etc.