Army tail fuzes contain the primer detonator, but the booster charge is housed in an adapter booster which is considered an integral part of the bomb base plug and should not be removed. The adapter booster also serves to seat the fuze.

Four adapter boosters are found in use in the base plug of Army bombs; the M102, M102A1, M115 and the M115A1. Since the inside thread diameter of the M102 and M102A1 is 1.5 in., bombs fitted with these adapter boosters receive Army designed tail fuze only, all of which have an outside thread diameter of 1.5 in.

In AN G.P. bombs the adapter booster is modified to permit the insertion of Navy hyd-rostatic tail fuzes (AN-Mk230-4-5-6) whose outside thread diameter is 2.0 in., typical of all Navy designed fuzes. The M115 and M115A1 adapter boosters which are used in AN G.P. bombs incorporated an inner sleeve or ring, which gives the adapter booster an in-side thread diameter of 1.5 in., permitting Army type fuzing only. When this sleeve is re-moved the inside thread diameter of the adapter booster becomes 2.0 in., and the Navy hydrostatic tail fuzes may be inserted.

The A1 modification on both the M102 and M115 consists of the additions of two base plate locking pins and an adapter booster locking pin to prevents the removal of the base plate and adapter booster when anti-withdrawl tail fuze are employed. See drawing on opposite page.

The nose fuze pockets of AN and other Army designed bombs have an inside thread diameter of 2.0 in. and are designed to take the AN-M103 (and variations). No adapter booster is used since the AN-M103 has its booster built into the fuze body and the fuze is threaded directly into the fuze seat liner. The M111 (and variations, particularly the M127), however, has an outside thread diameter of 1.5 in. and must be used in conjunc-tion with an adapter booster when desired for employment in AN and other Army bombs. This adapter booster, the M117, with an inside thread diameter of 1.5 in. to receive the smaller fuzes and an outside thread diameter of 2.0 in. to fit the fuze seat liner, converts the nose fuze pockets of G.P., S.A.P., L.C., 260 lb. frag, 90 lb. frag., 500 lb. incendiary, and 500, 1000, and 2000 lb. chemical bombs for use with the M127.

The function of the Army adapter booster is performed in Navy bombs by the fuze seat liner and the auxiliary booster. The fuze seat liner is an integral part of the bomb, and the Auxiliary Booster is used in the fuze seat liners of all Navy G.P., A.P. and depth bombs. On extra Mk 1 Auxiliary Booster is required to adapt the standard Navy nose fuze seat liner for the AN-Mk 219 fuze. The Auxiliary Booster Mk 2, which is designed primarily for insertion in rocktes heads, can be adapted for Navy G.P. and depth bombs fuzed with the AN-Mk 230 by fitting a .25 in. wooden disc spacer on the bottom of the fuze seat liner and placing two Mk 2 Auxiliary Booster above the spacer. When it is desired to use the AN-Mk 219 fuze in Army bombs, the Auxiliary Booster Mk 4 is inserted in the fuze seat liner.