Hi GBW: Now you got me to thinking about my use of the term "VIS". My (only) 1911 is a WWII-vintage GI model that has a distinct "bow tie" which extends about 0.010 inch forward of the flat bottom of the hole below it. My receiver "blueprints" are fuzzy copies of scans of original Ordnance Dept ones. They show this bow tie, but I can't decipher how far (if at all) it's supposed to protrude forward of the surface below. One place seems to show it 1/16, but another place on the same print seems to show it as ".005 -.005", implying zero protrusion (a flush surface) is allowable.
I recall reading somewhere in this forum that some guns don't have a bow tie, so for these I guess the VIS extends from the bed down to the bottom of the recess for the barrel lower lugs, a vertical distance of about 1/2 inch.
Anyway, the bow tie is what I refer to as the VIS. I always thought the area below it was recessed a bit to avoid the possibility lower lug contact too far down.
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