Buffer and Spring Question

Just bought a new CMMG CBR in 308.

Took off the ACS-L and accompanying buffer tube. Replaced with a UTG A2 buffer tube for Ar15 and Magpul MOE Fixed Stock.

Currently I'm using the buffer that came with the 308/ACS-L and using the spring that came with the UTG A2 Ar15 stock buffer tube.

Is this going to work or do I need to replace either the buffer or the spring or both?

Measure the depth of the two "tubes".

If they are the same, no changes required.

If the new one is deeper, you can simply add a spacer.

If the new one is shallower, you'll most likely need a different buffer & spring.

Pretty sure you need a buffer and spring for an AR-10, not AR-15.

If I read this correctly you have a carbine buffer in a rifle buffer tube with an AR-15 buffer spring. No good.

The AR-15 Spring is to light for the AR-10 which could cause harsher recoil and cycling issues. The buffer is to short for the rifle buffer tube. They have the little bumpers on them because they can/will bottom out in the tube which keeps them from traveling to far. With a shorter buffer and lighter spring the carrier could over travel.

Replace with a .308 rifle buffer and .308 buffer spring.

This be true, if ar15 spring/tube/buffer used it will not cycle right, will have chambering problems.

I had one cartridge stuck in my head.
Sorry.

Thank you gentlemen.

I went ahead and ordered a JP Silent Captured Spring. Thought why not? Anyone have any experience with these?