USN HC Projectiles - Purpose of Auxiliary Detonating Fuze without Nose Fuze?

Some US Navy High Capacity (HC) projectiles have a Dummy Steel Nose Plug (DNP, no nose fuze) with an Auxiliary Detonating Fuze (ADF) and a Base Detonating Fuze (BDF). Here’s an example I posted in an earlier thread from the Vietnam era (see projectile markings, even though it has an incorrect VT nose fuze): USN 5"/38 Caliber Questions

My question is about the function of the ADF when there is no nose fuze. In Navy documents describing the function of the ADF (such as OP 1664, US Explosive Ordnance), the description typically says that the ADF will not function without a nose fuze to initiate the detonation.

So what is the function of the ADF in an HC projectile without a nose fuze? Are some ADFs designed to detonate on impact or is it there for some other reason? Is it simply there to contain the explosive inside the projectile?


The wonderful Bulletpicker site has the source for the answer, NAVORD OP 2215 Navy Gun Type Ammunition dated 19 January 1959:,%20Navy%20Gun%20Type%20Ammunition%20(1959).pdf

Apparently the ADF is installed when the adapter ring is installed and the explosive filler added to the projectile. (Note that VT fuzed rounds include the ADF as an attachment to the fuze and require a much larger cavity in the explosive filler to accommodate the VT/ADF.)

The ADF serves no function in the explosive train when fired as a High Capacity round with nose plug installed, but allows the installation of a Mk 29 Mod 3 Point Detonating Fuze to bring it up to the normal HC configuration. Or, it can be used as AA Common if the nose plug is replaced with a Mechanical Time Fuze. With the MTF isntalled, these could be fired with the MTF set on safe and they would function as a HC round with the BDF alone functioning.

John, thanks so much for the reply. I looked through OP 2215 dated 1972, but it does not have the detail of the 1959 version.

It makes sense that the ADF would be there to allow swapping the dummy nose plug to a nose fuze.