I have to "respectfully" disagree . The barrel extension tool is holding the barrel extension which is screwed to the barrel which stresses the barrel from the rear rather than the front of the chamber. The stresses will be the same to the upper receiver no matter if the barrel is being held stationary from the front or rear of the chamber. The lessening of the twisting forces on the pin as the barrel nut is tightened would be same no matter which method is used. If this is not the case someone with a higher pay scale than me would need to explain it. 