I've had some email contact with APC (Alloy Products Corp) asking about thread size/pitch on some pin lock kegs I have and I got a less than satisfactory "I'd have to see the keg to be able to give you an answer" response.
I'm doubting you'll do much better. Seems to me you could measure them and then compare to ones on McMaster Carr?
Maybe buy a bunch that are close and see which ones work?


