08-25-2013, 06:15 AM
With lighter, shorter barrels, it's less of an issue and the torque of the barrel nut is usually enough to force the barrel extension flange against the face of the upper sufficiently.
With a 24" barrel, the preferred method is a tight-fit billet upper, or a bedded extension in a standard upper. Some guys will also sort through uppers until they find the tightest-fitting combo. I get more of a warm and fuzzy when I find extension to upper fits that are super-tight, but the trued face and trued barrel extension flange, combined with a true bore axis and trued extension will provide the foundation for an accurate gun. Lapping the bolt to the extension also helps, with a true bolt face.
So does Red Loc-titing the gas block once you have trouble-shot the gas system.
With a 24" barrel, the preferred method is a tight-fit billet upper, or a bedded extension in a standard upper. Some guys will also sort through uppers until they find the tightest-fitting combo. I get more of a warm and fuzzy when I find extension to upper fits that are super-tight, but the trued face and trued barrel extension flange, combined with a true bore axis and trued extension will provide the foundation for an accurate gun. Lapping the bolt to the extension also helps, with a true bolt face.
So does Red Loc-titing the gas block once you have trouble-shot the gas system.