There was a time when Pakistani surplus ammo was very good stuff. Especially their 303Br and 8x57 Mauser.
POF is one of the world's largest suppliers of just about every type of ammunition in production. They make ammo for all of the big nations, including the US, GB and France. Maybe even Canada????
One thing about their 303 BR is that their bullet diameter is .310 in. If it is larger it is pretty early stuff. I have a No4 MkII made by POF in excellent condition. I picked it up from a dealer that frequents this site but doesn't advertise here. Beautiful dark Circassian Walnut with very straight plain grain. I have several different diameter 303 bullets, from .310-316. This rifle wouldn't shoot anything but POF ammo well. That's when I measured the rifle's bore and the diameter of the POF ammo.
There is a very good chance it is under diameter for your rifle's bores.
As far as hang fires, the last few batches coming into North America leave a lot to be desired. The stuff should be sold as components only. To bad it's Berdan primed but those primers are available and it isn't a big deal to replace them.
The POF ammo from 25 years ago was good stuff but not very accurate in most rifles chambered for the 303BR. The brass is good though and resizes very nicely.
The last batch of POF surplus I saw was in the US two years ago. Pretty grungy looking stuff. Lots of corrosion on it (verdigris) and it was dirt cheap. It was sold as components only. The fellow I talked to about it said that the only thing that should be salvaged in his opinion were the bullets. Pull the bullets, dump out the powder, if it will come out of the case and throw the brass into a can of varsol to deaden the primers. Sell the brass and burn the powder or spread it on the flower beds.