20" barrel like god intended. Now get it in a real caliber, because 5.56 is good for platoons with autos in cities but most SHTF scenarios will have you alone or in small groups, and having a .308 is magnitudes more versatile.
Realistically even the m4 length barrel is wasteful outside of cqb - it drastically reduces effective range. The difference between 14.5 and 20 is the difference between being able to effectively hit at 300 vs 500 yards. Afghanistan really made clear how shit that is, because average engagement ranges were about 800, so only the m240 gunners and the radio operators had much use without spending several minutes bounding towards shit.
20" barrel like god intended. Now get it in a real caliber, because 5.56 is good for platoons with autos in cities but most SHTF scenarios will have you alone or in small groups, and having a .308 is magnitudes more versatile.
Realistically even the m4 length barrel is wasteful outside of cqb - it drastically reduces effective range. The difference between 14.5 and 20 is the difference between being able to effectively hit at 300 vs 500 yards. Afghanistan really made clear how shit that is, because average engagement ranges were about 800, so only the m240 gunners and the radio operators had much use without spending several minutes bounding towards shit.