I used to use 1oz 7s for pigeon, when I shot them regularly. Absolute mustard they were. I never have understood the perceived need for large shot/heavy loads for pigeons. 28gms 7.5 is practically the same load so will work just fine.
Have a sniff of it. If it has a strong ammonia smell it may be past it's best, but if not, someone will use it for sure.
I used to use it in shotgun cartridges and it was a favourite, until the supply became irregular.