montana Wrote:The shim does not go between the upper's receiver face and barrel flange, it goes between the barrel flange and barrel nut..This is why it is important to grease the front of the barrel flange and shims..
Putting the shim between the upper receiver and barrel flange can change the lock up timing/indexing, gas tube depth into the gas key and create other problems..
I assumed this was common knowledge. This is what I get for assuming things..
Montana,
On the Bison link video the shim is being inserted between the receiver and barrel extension. He snips his shims to do this.
Regardless, using words like Bubba and mangle are freighted with the assumption we dont know what we are doing. As I wrote, Ive removed a tooth before and it works. Im with Bonus on this one. Why risk the critical receiver-extension interface for the sake of lining up the gas tube. Alternatively, removing a tooth preserves the interface and is easier and cheaper.
Note also in the video he only torques to 30ft lbs and not up to 80. That acceptable MILSPEC range could align the tube without needing to buy his shims.