Gallahad
WCF stands for Winchester Center Fire. On the two Brits, how long is the 577 case? If it's less than 2 1/2 inches it may be military, the 577 Snider. If it's 2 3/4 or 3" it would be a sporting cartridge and should have either Eley or Kynoch, most often although there were others, on the head in addition to the bore. As always there are exceptions but generally speaking the sporting cartridges were marked with the manufacturers name and caliber and sometimes the type of load, NE (Nitro Express) or possibly LC (Light Cordite). Black powder and LC rounds generally had a lead bullet such as your paperpatched 577-450, NE bullets were jacketed.
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