That’s the ticket. Open it up and put a buffer of appropriate weight in the gun A lot of companies have tried to shrink the gas ports to compensate for running a slightly lighter and “less expensive to produce” buffer and it’s caused many a rifle to function poorly. Fixing a problem that didn’t exist. Sure, the 10 pound rifle is now 1.6 ounces lighter, but they’re trying to reduce gas and play with springs to adjust the physics of firing the rifle. I’ll take the extra ounce and a half to have a gun that eats anything.
Don’t know what the right bit is for you to go with, but get a wood dowel to insert in the barrel as a backer.