That Pakistani 303 was crazy stuff.
The POF 'Pakistani Ordnance Factory' marking got known locally as
.....Pride Of Frankenstein ....ammo.
It was really cheap but for a reason.
All the hang fires and duds you could ask for. Poor storage in extreme heat likely. Just plain poor quality ammo maybe.
But when the niuce Greek HXP boxer primed non-corrosive stuff dried up,,this was about all that was around as far a surplus (cheap) to shoot.
A little Brit Radway Green & Canadian Dominion was still around but at high prices and it too is corrosive and not always that reliable.
POF was super cheap.
If you do use it, just clean the bore with water and a touch of dishwashing soap added.
Wet Brush,,then Wet Patch..then dry and oil.
Check the next couple days for after rust but you likely won't find any.
Wipe the other metal parts down with the water dampened patch, dry and oil as well.
Don't make a big process of it.
I've shot corrosive ammo for nearly 60yrs and never lost a bore to rust yet.
Still using corrosive 8mm Mauser and 30-06. Bores still look new.