Originally Posted By: goose_boyOriginally Posted By: mj36639You do not need an action block. All you need is a good vice. I use two half inch thick pieces of polyethylene taped over the jaws(Hardwood like oak will also do). I chuck it in the vice sideways so the picatinny rail and the bottom of the upper receiver are the surfaces in contact with the polyethylene. Don't over do it. For assembling AR's you should at minimum have an armorers wrench, torque wrenches in inch and foot lbs, and moly anti seize grease in addition to common tools.
If you don't have much gunsmithing experience then an action block might be the way to go. Mistakes are expensive.
Mj, why the need for an in/lbs torque wrench? I've put together 3 ARs from scratch and have never needed this tool. I'd spend the money on a proper action block before I'd even think of an in/lbs torque wrench for an AR.
To the OP - just spring for the action block. It will make things so much easier and it is the right way to do it. You'll kick yourself for not spending the 30 bucks or so if you ruin a 100 dollar upper, especially after trying to find one to replace it. You can always rent it out too, I've always believed good tools pay for themselves.
I use an foot lbs torque wrench to tighten the barrel nut and an inch lbs torque wrench to tighten the flash suppressor. I use these tools because I assemble my rifles following Army Technical Manual 9-1005-319-23&P.
The manual dictates 30 foot lbs to mount the barrel with a maximum of 80 foot lbs for final barrel alignment and 15-20 inch lbs to properly index the flash suppressor using peel washers. Now if you use crush washers or a different style flash suppressor like the Vortex then the Inch lbs torque wrench is not needed; because the Vortex does not use washers and crush washers do not have a specified torque setting.
I deviate from the manual in regards to the action block because AR-15/M-16 action blocks were designed prior to the flat top picatinny rail M-4 upper receiver. When the rifle had a built in carry handle the receiver only had one flat surface. Current upper receivers have two.
Can you assemble an AR without the proper tools? Sure you can. That doesn't mean it's a wise thing to do. We are both advocating deviations from the Army TM. However my method ensures all of the correct assembly specifications are maintained.
The torque wrenches are also invaluable tools to ensure proper torque values are achieved when mounting scope rings and bases.
