I shot some, but having nothing to compare it to, it seemed like normal ammo. The ammo is very clean & dated 1969 with non-magnetic fmj bullets. It wasn't dangerous when I shot it. Nonetheless, most of us believe machine gun ammo is hotter than non-machine gun ammo, but I don't know how accurate that belief is. I never had reason to crono the linked ball. It seemed to work good. Mostly I pulled the bullets and powder & reloaded with H4895 & 150 soft points.
I tried using a Berdan depriming device so I could reload the military cases but that was a hassle so I gave up on that idea. I eventually acquired some Graf brass which worked well so I never used up the ball. I tried using necked up 6.5 Swede brass, & it worked, but the cases bulged too much when shot. They did function okay, though.
I appreciate all your help. Now I have an idea as to what I should get for it.