This is our experience: If an index pin shears - its a cheap pin or pin installation problem (big hole, pin at an angle, misdrilled hole). We use the Reaction Rod on all our builds and all our torque testing of barrel nuts. We have tried to torque to failure the Geissele barrel nuts and have gone to 150 ft*lbs. This is me hanging on a cheater bar like a monkey and two guys sitting on the bench so it doesn't flip over. No shearing of pins. And we have done this lots of times.
I believe that more force is put into the front torque surface of the barrel extension than the threads, therefore the Reaction Rod put LESS torque on the index pin.
THAT BEING SAID - I hear everyone and have heard everyone who disagrees and we have developed a super duper Reaction Rod that puts all these issues to rest. If you so desire you can install a barrel to an upper with no index pin and it will install and stay lined up perfectly.
And you can still use the indexing feature of the Reaction Rod to hold your upper so you can work on sights, gas blocks, muzzle devices, etc.
I have these made, just need to write instructions because the use of this Super Reaction Rod is not brainless.
The reality check is in the mail. --Cave-In
If I don't respond to you, it's probably because you're on my ignore list.