I got a box of the same exact ammo from a shooting buddy.
He bought it and didn't notice it was LRN. He shoots only jacketed. I fugured, I'll take it, shoot it and scarf the brass. I can reload cheap, but this was free.
I noticed the ammo was factory reloads. Several headstamps, mixed nickel and brass.
I shot the box, last thing before leaving the range.
I have been shooting for over 40 years, reloading for about 25.
I have *never* seen ammo that was so crappy. It was dirtier than the worst combloc stuff I have ever shot, and I have yet to encounter any load that leaded the barrel so much.
It took four good hard cleanings with a good soak in between to finally get all the lead out of the barrel. It wasn't in streaks, like most, it looked like a topo map of the Rocky Mountains.
I have shot other UltraMax ammo, found it to be ok - nothing special. The 500 SW loads were so soft they were only good for the brass. They chronoed at about 840 fps (325 gr JHP). Their website claims 1400 fps - not likely unless you duct taped some of it to a bowling ball and dropped it out of an airplane.
I would pull the bullets, dump the powder and bullets and save the brass and primers - reload, then leave them at the range. This, coming from someone who will dumpster dive in a heartbeat for one brass case.
Of course all of the above is my experience and opinion, as always, YMMV.
BigSlick