While doing a research for another article and looking for different information, I visited Indonesian Pindad’s website. Their small arms page shows the different models of their SS-1 and SS-2 rifles chambered in 5.56x45mm. But then I noticed a couple of rifles designated as 7.62mm ones. Just by looking at the magazine size in relation to the weapon they didn’t seem to be 7.62x51mm rifles. I thought maybe Pindad has chambered these guns in .300 Blackout? Anyway, going to one of that rifles’ pages I saw the full caliber designation – 7.62x45mm! What in the world is that? Has Pindad decided to give a second chance to the long extinct 7.62x45mm Czech cartridge? No. It turns out this cartridge is designed by Pindad somewhere in the early 2000s. Nevertheless, I think many of our readers are not aware of it, too.

It is most likely a necked up 5.56x45mm NATO brass to 7.62mm caliber. Pindad makes these cartridges in 3 versions. The first one (MU-11TJ) is shown in the top image of this article. It has a 108 grain round nose FMJ bullet. The muzzle velocity is about 1,850 fps (565 m/s). Ballistically, it is roughly similar to the .30 Carbine cartridge.

The second version (MU-11K) is probably a less-lethal load with an 8 grain bullet made of Polyoxymethylene (POM) which is some sort of polymer material. The muzzle velocity of this load is 1,035 fps (315 m/s).

Lastly, there are two types of blank cartridges (MU-11H, MU11-TG) with black and red color codes.

And here are the rifles chambered in 7.62x45mm caliber:

SB1-V1 with a 14.3″ (363 mm) barrel

SB1-V2 with a 9.7″ (247 mm) barrel

Presumably, this cartridge is headspaced on the case mouth. It should also require special magazines (other than STANAG) but will fit in the same magazine well.

The information on this cartridge is very scarce. All I can do is to guess the answers to the questions that arise concerning this cartridge. If they needed a 7.62mm cartridge conversion for 5.56×45 rifles, why didn’t they go with .300 BLK or 7.62×40 WT or designed a similar cartridge? Such a cartridge would be more versatile in terms of bullet choices and velocities and wouldn’t be merely a ballistic copy of .30 Carbine. Maybe these cases are easier to mass produce with minimal changes to the 5.56x45mm production line?

I am sure you have a ton of similar questions too. If you know more about this cartridge, let us know in the comments section.