Some torpedo help here

[Mush Martin]

In US torpedos it was advantageous to use offset angles with impact
triggers as well as a perpendicular impact tended to jam the firning pin
in the exploder. these difficulties I think were not unique to the USN,
both magnetic and impact exploder issues were had by most navies but the issue lingered in the USN where it was dealt with more quickly in German and British and Japanese navies.