I guess I'll put my pictures up. Solution is 5% citric acid, which is an old arsenal cleaning solution the NRA published. That's a higher concentration than others have mentioned, but does last forever. Add 7 oz to a gallon of water. Citric acid has some water softening capability, so detergent probably isn't required. I squirt a little Dawn in to help suspend dirt and cut through residual gun oil, but I'm not going to next time I make some up, just to see what how it compares.
I got 10 lbs of the citric acid for $2.70/lb, postage paid, from this guy
. Prompt service. That's enough to make up 23 gallons, which would last you a long, long time. Smaller quantities cost more per pound, so it's a good joint purchase project for yourself and some club members.