I'll just add that there are different Schraeder valves that physically can be screwed in, but would cause issues. Most common are for auto & bike tires, and I think they interchange. AC ones have special rubber for R-134A. The ones in the tip of a compression gage must have a very weak spring so they pop open easy to not affect the pressure reading, they usually have a white ring. I tighten all finger tight, using the special tool (~3/4"D handle), maybe 2 ft-lbf.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans