Please help with buffer and buffer spring weight

I have a 16" Mid-Length AR. Up until now, I have been running a standard carbine buffer spring and buffer. I just upgraded the BCG to an LMT Full-Auto BCG. I was planning to upgrade the buffer spring to a Wolff carbine spring, but I’m not sure if the combo of the heavier BCG and the heavier spring could make the AR unreliable. What is the best way to go here?

Also, I am finishing up an M4gery with a 14.7" barrel with a perm. hider. My plan was to upgrade the buffer spring on it too to the Wolff spring and to upgrade the buffer to an H buffer. It too will have an LMT Full Auto BCG. Is this the right combo for this one?

I don’t have the ammo or the cash to do a lot of experimenting so I really need to try to get this right the first time. Thanks in advance for all the help.

The reason the H buffer and heavier CAR length buffers were designed was to slow down carbines which cycled very fast (these had CAR length gas systems).

You’re running a midlength with a M16 carrier which doesn’t have these problems.
Ideally you only need a CAR buffer, will it run with a H? Probably. Will it run with an H2? Probably. But you’ll not have any benefit from a heavy buffer and it could have problems running dirty, dry and with weak ammo and when it does work it’ll have more felt recoil and muzzle lift.

I’d recommend a CAR buffer and a standard rate spring for your set up.

I assume your answer applies to the middy. What about the M4gery I’m building? Would you go with a heavier buffer in it?

Depending on the barrel make and gas port size probably a H or H2.