Over a year ago a Spanish reader emailed me to ask about the strange cartridge he found (pictured above). It had a ~7.62mm sized rifle bullet in what looked like a 9mm pistol cartridge case. Carlos wrote …

I recently moved to my grandmother‘s house in Madrid to start my university studies. I am sleeping in my uncle‘s old room. While I was looking in the wardrobe, I found a box full of cartridges, probably picked up by my uncle while doing the mandatory military service. Between them I found an odd looking one. It is marked 7.92×24.5 FNM-78. I think that he did the military service around the year 1978, that might have to do something with the markings. The round is quite strange looking. It looks like an 8mm mauser bullet in a necked down pistol case. I have never heard of any such ammo being used in the spanish army or in any firearm. It might be an experumental PDW round or something like that. I am sending you a picture of the cartridge compared to a 7.62 NATO case and a 9mm largo round next to the actual bullet and case separated. The bullet looks like a standard ball bullet with lead core.

I was not able to identify it, but Carlos persisted. He wrote in an email to me a few days ago …

I finally found the answer! It is meant to be used in a training insert for the M20 rocket launcher in Portuguese service and the INSTALANZA 88,9 mm rocket launcher in Spanish Army service. There are two versions of it, one with a 7.92 mm bullet and another with a 7.62 mm bullet.

The weakly propelled 7.62mm rifle bullet must be a ballistic match for the rockets fired from Spain’s Instalza 88.9mm M65 rocket launcher.

Instalza 88.9mm M65 rocket launcher

Thanks Carlos for sharing that info with us.