Buffer weight plays a major role and I usually start with an H2 or H3 depending on the setup. A heavier buffer can really help to slow down the bolt speed especially when you're dealing with all that extra pressure from the can. If you're still experiencing harsh recoil impulse, definitely consider checking out Sprinco springs. One thing that made a significant difference for my 11.5" was switching to a low back pressure can mount. Both KeyMo and Plan B seem to vent better than the standard direct thread setups. It’s a lot of trial and error. Start with the AGB, gradually increase your buffer weight and see how it goes from there.