Did a search and really didnt find the answer to what I am looking for.
I want to build a kit from the ground up and the only part I am unsure of is installing the barrel. I have the ARMY TM so I am familiar with the torque values (30-60lbs), and the benifit of torquing and losening 3 times to ensure good thread contact. I am also familiar with lining up the barrel nut by tightning (if necessary) to allow clearance for the gas tube)
Why are action blocks recommended over barrel vices? The ARMY TM specifically shows the use of a barrel vice. Do I need a Action Block? I already have the Barrel Blocks.
I am deathly afraid of breaking the index pin, but am unsure of how it can be stressed if the barrel is securely locked in place in the vice. If the barrel does move in the vice, shouldn't the upper reciever move also? You would think that if the reciever moved with the barrel it wouldn't stress the index pin.
Another question I have is directly related to what is stated in the ARMY TM. The ARMY TM states that after you install the barrel you should lood through the upper reciever (through the barrel) and align it on a vertical object (so it bisects the hole in the barrel) then it says to look at your iron sights. The vertical line should align with the iron sights. If it doesn't the TM says you should reinstall, and if that doesnt work you have a worn out upper reciever.
So, since this will be a new kit, do I need to worry about the above? How will reinstalling the barrel make the iron sights line up better with the vertical object? Only thing I can think of is that the upper reciever has too much play right from the get go. But I could be wrong.
Thanks for all your help!