OP 1664 - U.S. Explosive Ordnance (Vol. 1); Part 1 - Projectiles, Propellants, and Projectile Fuzes; Chapter 3 - Projectile Fuzes; Section 6 - Base Fuzes for Projectiles: Base Detonating Fuzes Mk 31 and Mk 36

U.S. EXPLOSIVE ORDNANCE

PART 1 - PROJECTILES, PROPELLANT,
AND PROECTILE FUZES

Chapter 3 - PROJECTILE FUZES

Section 6 - BASE FUZES FOR PROJECTILES

Base Detonating Fuzes Mk 31 and Mk 36

Projectiles used in	4"/40 H.C.
Markings	B.D.F. Mk 31 Lot -
Over-all length, inches	4.68
Delay, second	Mk 36 - 0.01 Mk 31 - None

Remarks: This fuze is moisture-resistant. These fuzes are almost identical to the Base Detonating Fuze Mk 28, differing only in length. Because of the small explosive cavi-ty in the 4-inch projectile, the Base Detonating Fuzes Mk 31 and Mk 36 have been made two inches shorter, with an external tracer.

Mk 31 and Mk 36 differ in following:

Mk 36 has a delay of 0.01 second; Mk 31, no delay.

Mk 36 has a stronger anti-creep spring.

Mk 36 has a chrome-molybdenum detonator plunger; Mk 31, a pearlite manganese steel one.