
The M38A1 Fuze is standard for the Mk II round. It is a typical nondelay fuze, being located in the base of the projectile and having no delay between the firing pin and the detonator. There is no positive separation between the detonating elements and the booster, so the fuze is not boresafe.
The M38 Fuze is limited standard for the High Explosive Mk II Shell, having been replaced by its modification M38A1. The A1 modification was a change in the detonator assembly. The M38A1 contains priming mixture, lead azide, and tetryl in the detonator whereas the M38 Detonator is made up entirely of mercury fulminate.
Setback forces cause the ring and sleeve to move to the groove in the firing pin, allowing the firing pin and detonator to be separated only by the firing pin spring. Impact forces the sleeve and firing pin to move as a unit against the spring, causing the firing pin to impinge the detonator and fire the fuze by impact inertia.
Detonator M18, tetryl booster
Length, overall - 1.9 in, 48.3 mm
Length, intrusion - 1.68 in, 42.8 mm
Diameter - 0.91 in, 23.1 mm
MIL-HDBK-146, Fuze Catalog (1982)
TM 9-1385-51, Ammunition (Conventional) for Explosive Ordnance Disposal (1967)
TM 9-1904, Ammunition Inspection Guide (1944)