That is a nice one, not many C grade 10 Lifters were made. That is is a great find!
Assuming there are no issues with the gun that would make it unsafe to shoot, you can get started with brass shells and black powder(what the gun shot when new). Fairly quickly.
If you have a chamber gauge, you can measure the chambers. Almost of the 10 gauge lifters I have come across are 2 5/8" chambers, though they could be 2 7/8". You could play it safe you could just get 2 5/8" shells, you will have plenty of room in either shell.
Track of the Wolf is a great company/website that sells the brass shells(with Parker headstamps) and all of the components to get you started. I would also recommend this booklet:
https://www.trackofthewolf.com/Categ...BOOK-HL-10-BSS
Congratulations on that beautiful Parker!
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