It depends upon the variables of your setup, such as gas port hole size, type of ammo, strength of buffer spring, etc. If you're overgassed (relatively common with Grendel carbine and midlength gas systems), a heavier buffer might be helpful.
All that being said, the H3 is probably the most recommended and used with the Grendel. But that doesn't necessarily mean that it would be ideal in your rifle.
ETA- An adjustable gas block often helps to tune a setup without changing other parts of the system.
All that being said, the H3 is probably the most recommended and used with the Grendel. But that doesn't necessarily mean that it would be ideal in your rifle.
ETA- An adjustable gas block often helps to tune a setup without changing other parts of the system.
Drifter