http://i369.photobucket.com/albums/o...medic/bar2.jpg
Shug, the GI spec calls for a 45* shoulder but as you pointed out standard countersinks are 82* and not 90*. I'm not sure about aftermarket barrels. Like Orlando said, this kind of fine tuning is reserved for match rifles. I just like having cool tools.
I would think the angle is important otherwise isnt it possible that the lock wont be against the barrel chamfer but just tigtened against the gas cylinder which would be defeating the purpose as all stress would be on the barrel threads
Orlando,
The gas cylinder doesn't have a hard stop from the splines before the gas lock reaches the chamfer, so I only have interference when the GCL is tightened against the actual shoulder on the barrel. Then the plug secures the GC to the GCL, which is solidly pressed against the barrel shoulder by the threads.
On the Krieger barrel, there is no chamfer on the barrel shoulder; it's flat so I'd have to counter-bore rather than countersink to have parallel mating surfaces. On my SA, there is a proper chamfered shoulder. But no matter what the angle of the GCL chamfer is, there will be interference when chamfer meets shoulder. If the chamfer angles match, both chamfers mate across their entire surfaces. If the angles differ, you'll have much less surface actually in contact. But with the relatively soft metal that the barrel and GCL are made of, there is some deformation and the metal creeps into a shape that somewhat matches the mating surface. End result is the shoulder still fixes the geometry of the GCL and GC.
I'll get a chance to get out to the range in the next week or so, and I'll report back on whether or not any play develops after cycling. Worrying any of this is probably overkill, but I enjoy experimenting even if it doesn't lead to anything useful. Plus I get to exchange ideas with others who forget more about Garands in a day than I'll ever know in my lifetime.
Allen