Please forgive my ignorance, but in what way does swapping out to a "pigtail" or "fat-boy" gas tube decrease perceived recoil? All the gas tube does is provide the conduit through which the tapped off combustion gasses provide the energy to cycle the bolt. The end of the gas tube still has to fit into a standard gas key.

Recoil energy is recoil energy no matter what, cant cheat that. What you're looking to do is either try and counteract the recoil energy at the muzzle and/or tune the travel of the BCG as it reciprocates.

If you want to decrease how you perceive recoil, there are different methods.

1. You can increase the static mass the gas has to overcome in order to cycle the bolt. Slowing down the bolt will lessen perceived recoil. This can be achieved by installing a heavier buffer (H, H1, H2). You can install a heavier full-auto bolt carrier assembly. Keep in mind that any change comes at a price. Increase amount of static mass the combustion gasses must overcome, you can induce short stroking, weak ejection. Your rifle may become sensitive to the bare minimum propellant charged practice ammo.

2. Increase the progressive resistance the combustion gasses must overcome. Install a stronger recoil spring. Install a hydraulic buffer.

3. You can install a muzzle brake. Redirect the combustion gasses coming out of the muzzle end to counteract the force of the recoil energy.

4. Install a softer recoil pad on your butt stock.

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-John