The action only unlocks early if the gas port is not right... IMHO.
Overloading it is not right.
You'll notice that when people want to load gasguns like Garands/M-14s over the pressure/pressure curve levels of GI ball, they resort to such things as ported gasplugs. Look at the dedicated 1,000 yard M1As shooting 190+gr bullets.
The same basic thing applies to hot loaded AR15s - people tighten the gas port or add heavier buffers or Tubb carrier weights.
