Need clarification with US MINE FUZE M1A series

[MINENAZ16]

Hello,
2 questions :
-On the left, AT Mine fuze M1A1 : what is the hole on the side is for ?
-On the right, no hole on the side, is it the same designation for this fuze ? Is it M1A2 (I remember such a hole on the A2) ?
Regards

 

[MINENAZ16]

Bump this thread

 

[weberoed]

If I am seeing correctly, the pone with the holes are the practice fuzes that have a small spotting charge

 

[MINENAZ16]

If I am seeing correctly, the pone with the holes are the practice fuzes that have a small spotting charge

Thanks for your reply but we found these fuzes fitted with live detonators with HE M1A1 mines in a small WW2 US minefield.
Herewith a picture of M1A2 with the same hole on side. So what is the use of this hole and why this hole is missing on the other igniter ?
I have no good US diagram with this detail.