I agree with Frank. I always run a minimum of 3 factory rounds through a virgin build, just for pure function test. Looking for bolt lock back, stripping a fresh round from the mag, and the ejection angle. That is the only reason I even have factory ammo in my stash. That way you know you are starting with a fully functioning gun and if problem occur with handloads you know where to look.
BTW ***'s 18" ers are mid gas and 4198 should have no issues with cycling.
But if you continue to get short stroking there are a few different ways to fix it. Cheapest is to clip the recoil spring a bit to reduce the power of spring, or buy a reduced power spring like a wolf, or open up the gas port one size. If it where me I would try a reduced power spring, but I am assuming you are running a standard carbine buffer and spring.
FYI a heavier buffer will only make the short stroking worse.
BTW ***'s 18" ers are mid gas and 4198 should have no issues with cycling.
But if you continue to get short stroking there are a few different ways to fix it. Cheapest is to clip the recoil spring a bit to reduce the power of spring, or buy a reduced power spring like a wolf, or open up the gas port one size. If it where me I would try a reduced power spring, but I am assuming you are running a standard carbine buffer and spring.
FYI a heavier buffer will only make the short stroking worse.