I would also like to add, most of the timing issues I've seen come from people running short barrels (less than 20") on AR's.
The AR was designed for a 20" barrel. Once you start cutting the barrel back, you start to tamper with the timing of the rifle. To counter act this, people/companies put heaver buffers and sometimes springs in the guns. Others see the issues with extraction (with brass) and put super springs in their extractors. All of this is a band aid to the real problem, the gun is out of time and pulling the case prematurely causing undue stress and wear.
Toss steel cased ammo in the mix and your making your rifles problems even more pronounced.
Since many people refuse to believe their rifle needs service, they blame the ammo.
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