OP 1664 - U.S. Explosive Ordnance (Vol. 2); Part 6 - Bombs and Bomb Fuzes; Chapter 20 - Bomb Fuzes; Section 2 - Army-Designed Bomb Fuzes: M163, M164, and M165 (Nose Mechanical Impact)

U.S. EXPLOSIVE ORDNANCE

PART 6 - BOMBS AND BOMB FUZES

Chapter 20 - BOMB FUZES

Section 2 - ARMY-DESIGNED BOMB FUZES

M163, M164, and M165 (Nose Mechanical Impact)

Functioning
M163	Instantaneous; 0.1-sec. delay
M164	Instantaneous; 0.01-sec. delay
M165	Instantaneous; 0.025 sec. delay
Fuzes used with	M160, M161, or M162 normally;
	AN-M100A2 series
Arming data
	Inst.	Delay
Revolutions	750 (approx.)	500 (approx.)
Air travel	1,710 - 3,625 ft.	1,140 - 2,420 ft.
Minimum vertical drop at 200 m.p.h.	1,775 ft.	915 ft.

General: The Nose Mechanical Impact Fuze M163, M164, and M165 correspond to the AN-M103A1, AN-M139A1, and AN-M140A1 respectively, except for the arming screw of the M163 series, which has 32 single threads per inch as against 14 single threads to the inch as against 14 single threads to the inch in the earlier fuze. Although the length of the M163 arming screw is reduced to 0.5 inch, the crash-proof feature is retained in the new series by the addition of a second shoulder, higher up on the arming stem, which bears against the bottom of the arming screw.

This series of fuzes is designed as a companion group for the M160, M161, and M162; and serves to eliminate the difficulties discussed with reference to the M160 series.

To distinguish the new series from their prototypes, the following markings are em-ployed: the top of the M163 vane cup is painted completely yellow; and, in the M164 and M165, the vane cup is painted yellow except for the black sections indicating the delays.