I run a few variant caliber ARs that benefit from H2 to H3 buffers, mainly to slow the cycling for reliability.
In 5.56, not necessary, but some prefer the feel.
I've bumped a 5 oz rifle buffer up to 7 oz for a 16" 7.62x39 upper and it caused cycling issues.

It's easy to try, cheap tungsten weights are available on Amazon, and as mentioned above, you can remove the aluminum spacer and add two steel or tungsten weights, or just replace some of the steel weights with tungsten.

Just gonna depend on your build, your mags, and your preference.
I've found changing spring rates has a more drastic effect than buffer weights.