02-24-2014, 04:06 AM
As coincidence has it I happen to have the Brownells tool, the PRI tool and I also have a Mega SBU upper, I prefer the Brownells tool over the Geissele in one important feature. The Geissele version is used by mounting it in a vise and then using a barrel nut wrench to tighten the nut. Problem is the square drive in the wrench is offset so you have to recalculate your torque setting on your torque wrench. When using the Brownells tool you mount your barrel nut wrench in the vise and the Brownells tool has the square drive in its middle so you don't have to do any recalculation for your torque wrench. As far as the Mega SBU upper, it is made to have a heat fit. You must heat it up to get the barrel in or out. I have been told you should never hit the barrel or receiver to get them to fit. If you do you stand the chance of warping your receiver and if you have a heat fit like Mega without the heat you will damage it. I prefer holding the receiver with my PRI tool, it can hold the upper either by the picatinny rail or the pin lugs, when I am going to be applying heavy force I use the picatinny holder so as not to risk the pin lugs being damaged.