[Bindernut]

INDEP in Portugal made FNM headstamp ammo in many calibers and in both FMJ military and soft-point sporting ammo. They were not just a military contractor. No longer in business.

I got a bunch of '60s & '70s vintage FNM 6.5mm Swede and 8x57mm back in the early '90s from some importer. The 6.5x55 was VERY good quality ammo, I couldn't really tell about the 8x57 since the old K98 I was shooting it out of wasn't really fit to shoot. It was all boxer-primed and the boxes said non-corrosive.

That does look like .303 British to me. Probably a 174gr FMJ mil-spec load.

 

[Bindernut]

That is not 8x57 or 6.5x55, if I had a dollar I'd bet on it being a .303 British case.

I never said it was Swede or 8mm Mauser. I'm pretty sure it's .303 too.
Was just illustrating that you will find INDEP ammo with a FNM headstamp in many calibers. Think of them like a Portugese version of Winchester, Federal, Dominion, etc...