4198 is the most notorious powder for causing short stroking in AR's. Just a tad too fast burning and not enough gas at the port. Those that report solving short stroking with 4198 powder have used maximum or near maximum data. I've read many issues over the years with 4198 in AR's. I wouldn't even try loading with it in .223/5.56 autoloaders. Your rifle may cycle with it if you keep it wet with oil and near maximum loads?