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| U.S. EXPLOSIVE ORDNANCE |
| PART 1 - PROJECTILES, PROPELLANT, AND PROECTILE FUZES |
| Chapter 3 - PROJECTILE FUZES |
| Section 6 - BASE FUZES FOR PROJECTILES |
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Base Detonating Fuze Mk 21 Mods 0 and 1 |
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Projectiles used in |
6"/47 A.P., 8"/55 Common 7"/45 A.P., 8"/55 Sp. Common 8"/55 A.P. 12"/50 A.P. 14"/45/50 A.P. 16"/45/50 A.P. |
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Threaded length, inch |
0.96 |
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Threads |
11 L.H. |
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Material |
Body - manganese steel Nose cap - duarlumin |
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Delay, second |
0.035 |
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Description: Except for the dimensions noted above, the Base Detonating Fuze Mk 21 is like the Mk 19, and has practically the same operation; however, this fuze is designed with an additional plunger-locking unit. The plunger body is drilled in four places, and four balls are placed in the holes. On forward motion of the plunger and under centrifugal act-ion, the locking balls fly out of their recesses into the forward the plunger in the forward position. This locking feature is provided to insure alignment of booster lead-ins and de-tonator lead-outs during the long delay period, when the projecitle is subjected to vio-lent shocks of penetration. |
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Remarks: The detent springs in this fuze are considerably weaker than those used in the Base Detonating Fuze Mk 28. |
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The Mod 1 of this fuze is identical to the Mod 0, except that it is fully moisture-resis-tant. |
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