Mills Bomb No.36 info. needed

[rob love]

I have had a few of them converted to piggy banks. I bought a couple of auction arms back in the day, and would have the sender mail them as piggy banks, since listing them as grenades would in no way facilitate their entry into Canada.

I checked the threads on a couple 36Ms and what I found was that the threads are 20 threads per inch. The smaller plug is 9/16 in diameter, and checking available thread charts, that size does not appear to be UNF, BSF, or any of the other options.

One option is to grab a tap that is 20 TPI and drag the tap across the threads to restore them. I have had luck with this method in the past on various damaged threads on stuff like differential drain plug holes.