81mm Shell, M43A1B1
This article is from TM 9-1904 which is available on this site.
The contents have been supplemented with modern photos and comments or additional information added in some instances.
Date Compiled: 7/17/2007
Editor: Chris Guska
SHELL, H.E., M43A1B1. This shell was designed to replace SHELL, H.E. M43 and M43A1
Shell body. The body, filler, and bakelite fuse well clip are exactly the same as in the M43. The fuse used is the Point-detonating Fuse M52, which has a super quick action. Due to the light weight and blunt nose of this shell, very little penetration can be obtained. This shell, as the M43, is designed, therefore, to produce fragments as its primary function against personnel in the open and against barbed wire entanglements. Fragments to be effective must be above ground. The use of a super quick fuse to burst the shell above ground is therefore mandatory.
This shell differs from the M43 and M43A1 in that the fuse adapter ring has been omitted.
Fin assembly. The fin assembly is similar to that previously described. It differs in that the flanges on the fins for holding the propellant increments are omitted, as they are not necessary with the newer type increments. Later models, without any change in designation, have the hollow end threaded in the inside so as to receive the new percussion primer.
*** Note - fin assemblies were made and fitted to M43A1 and M43A1B1 that accepted the M3 Ignition cartridge rather than the M33 percussion primer and M6 Ignition Cartridge. The use of the M3 Ignition cartridge did not end with the M43. M43A1 tab-less fin sections were made that accepted the M3 cartridge and used simultaneously with the threaded type for M6/M33 Combination***
Ignition cartridge. The Ignition Cartridge M6, red, consists of a cardboard container having approximately 120 grains of double base powder. It supersedes the M3 red and differs from it in that the percussion primer is no longer part of the ignition cartridge but a separate component.
The Percussion Primer M33 is a relatively new component. The percussion primer is contained in an aluminum head and is threaded so as to screw into the end of the cartridge container after the ignition cartridge has been inserted. The advantage of this type of percussion primer and ignition cartridge is that the whole assembly will leave the mortar with the shell whereas the older type ignition cartridge would, due to the force of setback, at times leave its brass head in the trench mortar weapon, fouling the firing pin and possibly causing a misfire in subsequent rounds.
The Propellant Increment M1 consists of square strips of double base powder sewn together to form increments. Passing thru these increments will be found holes to increase the burning surface. These sheets are thin and flexible and will not crumple or break as did the old celluloid containers of double base powder used with the M43 Shell. Each increment has 117 grains of double base powder. Occasionally one corner edge of an increment will be cut away (notched) so as to bring the charge to the desired weight and specification. The increments are held in the stabilizer assembly by being placed diagonally in the holes of the fins.
The percussion primer, ignition cartridge and six increments make up the full propelling charge of a total of 822 grains of powder. The increments may be removed to adjust the propelling charge.
Zone of fire and range. This shell has the same number of zones of fire and approximately the same range as described for SHELL, H.E., M43.
Marking and packing. The shell body is painted olive drab with yellow stencil. It is packed one per individual fiber container, six fiber containers per bundle, one bundle per wooden chocolate-stained crate for overseas shipment. The rounds are completely assembled, ready to fire.
