If I'm not mistaken Lachowski testified that when attending Grosskreutz after being shot he found the glock on the ground and cleared it. There was one in the chamber.
The unspent ammo from the glock comes from Lachowski clearing it. Grosskreutz didn't rerack the gun, but he did have one in the chamber ready to shoot, meaning that he meant to take out Rittenhouse when he advanced before having his bicep blown off.
The unspent ammo from the glock comes from Lachowski clearing it. Grosskreutz didn't rerack the gun, but he did have one in the chamber ready to shoot, meaning that he meant to take out Rittenhouse when he advanced before having his bicep blown off.