I test fire every rifle/smoothie/pistol before it goes to its new home. It is a selfish treat I give myself after months of building. But it serves more practical purposes too. It ensures that everything is in harmony and functions flawlessly. And it gets the gun very close to being sighted-in. the new owner must do the final shooting to find out what works for them, but it also satisfies me that the rifles, particularly, are accurate.
The .62 half stock used a .613" pure lead ball (from a Lyman .610 mold), a denim .022" patch and mink oil or neatsfoot oil for a patch, over 100 gr. of FFg GOEX. I personally prefer 125 gr. with this loading, for best accuracy out of a .62 cal round ball rifle, but some shooters are recoil shy.
The .50 flinter fullstock was sighted with the same patch/lube combo and a .495" soft lead ball. I used 80 gr. FFg GOEX. I sight them at 50 meters...25 meters tells you little.
Some shooters don't use that much powder - wasteful (cheap) or too much recoil. But I use the same charges I hunt with. Target practice is also hunting practice. My experience tells me that these charges/loads, yield the best accuracy.
I appreciate the kind words, partners.