In a recent thread started by Shotmeister on his Navy ammo can, the discussion evolved to the use of electric vs. percussion primers on US 20x110 HS ammunition. It seems that designations applied (M95, M96, etc.) do not differentiate the primer type used as various TMs list them as both electric and percussion under the same designation. In other sources I’ve found that, if anything, this is indicated parenthetically as, for example, “M95, Armor Piercing Tracer (Percussion Primed)”. This seems a little odd as there has been little restraint in tacking on additional designators to distinguish variations in loadings of most other ammunition. An exception that comes to mind is the designation of (Steel Case) for other small arms loadings when the case material is the only difference from the basic “M” number.
The other question that arose was in regard to interchangeability between primer types in guns capable of firing one or the other or both. As is the danger when I encounter such questions, I started thinking…
The German developments of electric priming were to allow improved synchronization of thru-propeller firing guns. Later US use of that technology captured during WWII was applied with bomber defense turrets in mind to keep gunners from hitting their own aircraft and also to balance twin gun mount firing vibrations. While I believe the electric primed German ammunition and the guns firing them were electric only, TM listings of some item’s applications seem to indicate the US may have seen some versatility in the situation.
Perhaps there is interchangeability to an extent in that an electric gun could be designed able to fire both percussion primers and electric primers. Provided an electric primer could withstand (and not fire with) an impact required for a percussion primer, this would be a workable situation. A percussion-firing gun would require exclusive use of percussion primers, as there is no electric charge present but an electric gun using electric primed ammunition could have all the mechanics in place yet withhold electric current and discharge as required.
The electric contactor of a gun designed for exclusive use of electric primers needs only to engage the primer enough to allow current to flow to the primer. I would guess in modern applications of extremely high fire rates the use of electric priming is to reduce the mass of parts that have to move very fast. This, I think, is seen in the example of a 20x102 fired case (shown on the right) where the fired electric primer is barely dented. While I don’t have examples of 20x110 HS fired cases from any particular gun, for fun I also showed an electric primed M96 20x110 HS on the left and a WWII vintage percussion primed version at center. Note the M96 is stamped “ELEC”.
Pardon the rambling, but these things happen…Would be very interested to hear any thoughts out there on the “same designation for different primers” thing as well as the interchangeability of electric and percussion primed ammunition in general.