British 5.56x45mm with Electronic Initiated Primer, 1998

From the conference proceedings National Defense Industrial Association, Small Arms Systems Section Annual Conference, Exhibition & Firing Demonstration, 1998, is a presentation by representatives from DERA MoD & British Aerospace/Royal Ordnance (Electronic Individual Weapon (EIW): A Concept Update) concerning work in Britain on 5.56 x 45mm electrically initiated primer ammunition and weapon development. Extracts form the presentation:

Does anyone have any additional information on this program and/or examples of the cartridge?


Hi Brian I have these cartridge and this info is what came with it

                                           Concept Demonstration Rounds:
                                           Electrically primed 5.56x45mm Ball

                                                        Important notice

These notes refer to a quantity of 600 rounds of special electrically primed 5.56mm Ball rounds supplied by System Design Evaluation Ltd.

  1. The rounds are experimental in nature and should only be fired remotely , under precautions in case of gas escape fromthe breech.
  2. Because of the special primer arrangement the rounds must be fired using a special modified bolt with an insulated firing pin.
  3. The central contact (“pole piece”) at the centre of the primer must be protected from inadvertent contact with electric power sources.
  4. All of the capped cases used have been subjected to electrical safety tests and shown not to fire when subjected to the discharge from a 22 microfarad capacitor charged at 5 volts (0.28 mJ energy)
  5. Capped cases from the above test have also been exposed to a continuous voltage of 2.0 volts and maximum current of 80 mA for a minimum of 2 seconds without firing.
  6. All capped cases have been tested for resistance. Maximum is 358 ohms,minimum 3 ohms . Excluding values above 100 ohms (29) typical resistance is 17 ohms.
  7. A sample of 10 capped cases in a holder has been subjected to a mechanical impact sensitivity test using a 112 g (4oz) weight dropped onto a 1.5mm diameter hemispherically tipped firing pin from a height of 101.6mm (4.0”).No caps fired at this height or on a repeat test conducted with the same cases at a 203.2mm (8.0”) test height.
  8. Rounds have been loaded with 3.56 g M193 type ball bullets and a charge of 1.55g single based Nitrocellulose chopped tubular powder.Velocity of 924 m/s has been obtained at 12m from a 603mm length test barrel, similar to that obtained from rounds of identical build standard but assembled with percussion (CCI No.400) primers.This charge gives moderate pressures which should be sufficient to cycle the L85A1. If necessary a higher gas setting should be used.
  9. Because the disign of the empty cap assembly has not been optimised , there is a high probability of the central pole piece being expelled from the case head on firing , with consequent minor projection hazard and a small ammount of gas escape. The normal provisions for gas escape from a pierced cap (gas escape holes and captive firing pin ) should prevent this from being unduly hazardous. The problem can however be avoided if the firing pin is prevented from moving back in the bolt head by more than 1mm during firing.
  10. The rounds have been assembled without sealants and should be kept in a airtight container.


Thank you for the information and confirming that example(s) of this electrically primed cartridge exist.

Any chance of a picture of the headstamp/primer?

Thank you again,


box label




THAT WAS FAST! Great pictures!

Thank you again,


I wonder why they used a .223 Winchester commercial headstamped cartridge case and not a British 5.56x45mm case(s)?

Brian, maybe because British made cases are Berdan primerd and the electric primer needed a Boxer case?

Gyrojet et all:
Is the “SDE” on the label the manufacturer? If so, who is it?

SDE - System Design Evaluation. This is the same company that made the cast-metal 5.56mm L14A1 Drill round.

Jim, thanks a lot!
I have found their site:

Do you happen to know if “SDE” is an official NATO code?

[quote=“EOD”]Brian, maybe because British made cases are Berdan primerd and the electric primer needed a Boxer case?


Thanks! Sounds very plausible to me, especially since the sectional diagram above appears to show a boxer case with the electric initiated primer seated in a flat primer pocket!


At least one of the converted rifles still exists in the Shrivenham small arms collection.

The electric priming enabled the rate of fire to be varied in order to determine the optimum RoF for controllability. That turned out to be 300 rpm, something like a third of the typical RoF of a 5.56mm rifle. That would save a lot of ammo and greatly slow down barrel heating as well, but it’s complicated to achieve mechanically.