13" factory barrel assembly overgassed?

I swapped in a 13" FN barrel assembly for the factory 16" a few months back. I run an AAC 762-SDN-6 and the blowback is pretty significant. At 16" it wasnt too bad, but with the new barrel assembly I get a good amount of gas under my glasses and in my eyes even on the suppressed setting. The rifle functions pretty reliably (though not 100%) on the suppressed setting WITHOUT a can. You would think it would be tuned correctly from FN, but it seems it's a bit overgassed. Is this simply a matter of trial and error with larger gas screws? The gun runs 100% on the appropriate settings, but I would like to reduced blowback, recoil, and overall wear and tear on the rifle if at all possible.