A shelf life of six MONTHS? I am in trouble! I have some Goex I bought in 1992 and am still shooting. Actually, black powder will last indefinitely, unlike smokeless and BP substitutes.
Now a little trick I read about many years ago. Go down to the hardware store and get some of the "green scrubbies" which are used for finish sanding. Also get a bore mop of .45 caliber or so. Cut a green scrubby so it will wrap around the bore mop (which you have on a cleaning rod, of course). Spray it well with WD-40 and run it down the barrel and back. You will want to clamp the barrel in a vice with some leather or wood to protect it. You want a very tight fit of the green scrubby and mop in the barrel. Okay, now start stroking in and out, full length of the barrel. When it gets easy, replace the scrubby. Give it at least 100 in and out strokes. You are polishing the inside of the barrel here, and this is a one-time event.
Okay, now clean it well as suggested before. Hot soapy water in a bucket. I use dish detergent. You want to get all the WD-40 and other hydrocarbons out of there. Follow this with hot clean water to rinse the soap out. Let it drain and swab the barrel with dry patches. FROM NOW ON, USE ONLY NATURAL LUBRICANTS! Lube the bore with Bore Butter or similar. I use olive oil. Then use the same lube on your patches for you round balls. The rifle will load a lot easier and foul less.
At the range, run a patch down the bore between shots. Some folks advocate a lubed patch, I use a dry one. When I'm hunting I don't find this necessary. When I was up North and going after bunnies I would go all day without swabbing between shots, but then again, I would go all day and only shoot 10 times. But on trailwalks I never found it necessary either. Hmmm, I never thought about this before...
Not to scare you off, but you are going to want to try different powder, patch and ball combinations also. It's part of the fun of shooting the Holy Black. You can generally get precast ball in .490 and .495 diameter, and patches in various thicknesses. Start with say a .010 patch and .490 ball, then vary the powder charge to find the what gives you the best group. Shoot five shot groups at each powder charge. Then go to a different patch and do it again. Then do this all over with the .495 ball. Write the combination of ball, patch and powder on each target you shoot. Compare the groups to see which combo gives you the tightest group. A good rule of thumb is to use a powder charge 1 1/2 times the caliber of your rifle to start, then go up and down from there. Above all, have fun!
Let us know how you progress.
-Winter Hawk-