AR-15 shoulder set back

[Tex S]

How far should I be setting back shoulders in my AR to maintain reliable feeding but not overwork the brass?

[Unclenick]

0.002"-0.003". The smaller number is recommended by Glen Zediker. 0.002" is also how much smaller most new commercial brass is than a minimum length chamber. The reason I gave a range is it is hard to get a sizing die to hit the exact same number every time, so if you set for 0.0025" you are less likely to have an issue when a harder-than normal case goes through. Alternately, you can measure every case and run the long ones through again, which often fixes them.

Do note that if you use once-fired brass from other chambers, you usually need to resize them all the way down and fire them in your chamber at least once before using the smaller setback numbers becomes reliable.