That groove diameter at the muzzle you typed here is rediculously large! Are you sure its NOT .512", or even .502" Normally, grooves in barrels, by GM or Colerain, are going to run .010" deep each, for a total depth of .020" over bore diameter. If you add .020" to .490, you should get .510". If you measured the grooves diameter at .512, that would be close enough for a Colerain barrel.
Use a cloth patch like pillow ticking, that measures .018" - .020" thick for patching the .490" ball. Lube the patch the night before to give the lube plenty of time to sink into and fill the entire fabric. I generally will do 10 more patches than I expect to shoot the next day at the range, stacking them together with lube, so that the lube has the whole night to migrate through the cloth.
That should give you a good seal for the RB. In choosing the thickness of your cloth patching, you want to measure the cloth with a micrometer, or caliper, with it compressed. If you buy fabric from a fabric store, expect the cloth to have a substance called " Sizing" in it. This is a starch like compound that is put into fabrics to make the nap compress, and flatten, so that more cloth can be carried in a small space. YOU NEED TO WASH THE SIZING out of the fabric, in your washing machine, before thinking about adding lube. Measure the fabric by "crushing " it enough that you can just barely slide the fabric from the jaws of your micrometer or caliper. You should expect that the fabric will compress to 2/3 to half its thickness, depending on the fabric, when you drive the PRB down the barrel. To seal those deep grooves, so that gas does not escape through the grooves and tear or burn your patching as it goes by, you want the material to be 1.5 times the depth of the groove.
Sometimes, a gun requires an even thicker patch. In your case, since the groove is at least .011" deep, I am recommending the .018" thick patching material to start. But you may have to go to .020" patches to fill those deep grooves.
LUBE: Use a vegetable oil, like olive oil. Or Ballistol, which is mineral oil with additives. Stay away with petroleum based oils. You can also mix a more stable lube by mixing oil with beeswax that you melt. The more wax you use, the stiffer the lube is- like boot seal. The more oil you use, the softer the compound is, like cold cream. Oils alone work very well in cold weather.
In below freezing weather, you might want to add alcohol to the oil you take with you to the field to lube patches. Leave the wax lubes at home. Do not use water based lubes in below freezing temperatures. Its a race to see if the water evaporates before it freezes to your barrel. There are all kinds of lubes used. You can find threads on this issue below on the index page here under Accessories. The lube serves three purposes. It help the fabric seal gases behind it, it both protects the fabric from burning, and protects the bore of the gun from rusting on a hunt. With some deep grooved barrels, that is asking too much of fabric, and a filler or OP wad is used between the powder charge, and the PRB to seal the gases behind the PRB.( Patched Round Ball)
What size flint to use in your lock depends on whose lock is on the gun. And, without knowing the make of the lock, we can only speculate on whether it will spark correctly. There is a simple knapping technique you can use to sharpen the edge of the flint in the lock, and to square the edge to the face of the frizzen. But, you first need to determine the correct length of flint for that lock.
Put the cock at the half cock position, and then measure the distance from the front of the cock screw, between the jaws, to the face of the closed frizzen. Subtract 1/4" to leave room for your flint wrap, and a space between the edge of the mounted flint, and the frizzen. That should give you a ball park indication of the correct size flint you need in that lock.
You need to find someone who shoot flintlocks near you to help you through the learning process. Join the NMLRA. They have a link here. The NMLRA has a list of Local Charter Clubs in every state. That is the quickest way to locate someone, and some place to shoot.
What I can do with you and your " new " gun in a few minutes on the range, showing you what to do correctly, and showing you what is right or wrong about your lock or gun, would take lots of pictures of the gun, here, and lots of ink. We have done it in the past, but its very difficult to advise new shooters by email, or even over the phone. There are just so many potential sources of problems you don't even know exist, or how to find.
Go to Bob Spenser's website, , Black Powder Notebook
http://members.aye.net/~bspen/index.html
and read the articles there on Flintlocks. He has a separate article on Flintlock terminology that will help you communicate with us about any problem you see.
Powder charges:
Start with 50 grains of FFg Black Powder, and raise the powder charge by 5 grain increments, shooting off a bench rest, to find the most accurate group. Begin shooting at short range- 10-25 yds, to make sure you are at least hitting the paper! Then, move back to 50 yards. If you are shooting good small groups( 2-3 inches using open sights) at 50 yards, YOu are at least in the ball park of finding an accurate load for the gun.
Go to Dutch Schoultz's website,
http://www.blackpowderrifleaccuracy.com/
And order his "system" for $15.00. Its the best $15.00 you can spend to learn how to produce very small groups with your rifle.
