the known and the unknown - With a firearm regardless the vintage I will always choose the known! Know your equipment, know your setup, know your backstop, KNOW YOUR LOAD! - scary post!! at least in my book........ fyi - I know factory loaded ammo is supposed to be "safe" but after reloading as long as I have, as many different arms, and circumstances I have loaded for, and with all of the messing around I've done with getting the "right" load for rifles, pistols, and revolvers I still test fire when starting out even with a new can of powder, I test and work up to accuracy! Using anything I am uncertain of when it comes to my firearms, would Not be a thing I would do!
Get some fresh powder and be sure of your equipment! Even if you've gone through most of what you received!