I’ve got 11.5" BCM upper on the way, planning on getting a DD 7.0 lite rail for it. I will need to mount my 18 tooth blackout FH for my AAC M4-1000. With my KAC RIS no big deal because handguards go on last. I guess using the AR upper receiver block in the vice and then torquing on the FH is the way to do this properly. Thanks for any suggestions/directions.
The proper way is to affix the barrel in the vise not the upper.
Understood, but I can’t put the rail over the FSB and the FSB has to be installed prior to the FH.
Use two pieces of wood/delrin around the FSB and clamp it in the vise at an angle. The taper pins will be taking the load but you don’t have to go crazy on the torque of a AAC flash hider/mount.
Gotcha…hadn’t thought about that and had to ask the question because it sure seemed to me that I would be putting too much torque on the receiver using the upper receiver block.
Thanks for the help
On a related note, Robb what would you recommend with a long rail system without much exposed barrel to work with? Like a 12" rail on a 14.5" barrel.
I’d be interested to hear other ways of doing this also.
Sometimes as in this situation you have to use the upper block. What I would do would be to use a peel washer and with the barrel out of the upper get the flash hider to align using the appropriate peel wash and minimal torque (15-20ft lbs max). Then assemble everything and use the peel washer and Rocksett. This way your not really cranking hard on the barrel within the upper receiver.