Here's what I use straight from Mike himself, make sure you get the right windex.
"Maven: I just dump a jug of "Windex With Vinegar" into a gallon milk jug and then fill the remaining space with water. Such a jug should last for a couple of years even with a very avid shooter/competitor. (Like me.)
As for muzzle loaders, yes that solution works fine too. I cover the nipple with a patch and put the hammer down on it. Then I fill the barrel with the solution and let it set for a couple of minutes. Then I upend the rifle and let the fouled solution run out on the ground. After that a couple of patches should clean up everything else.
That certain variety of Windex is hard to find, so when I do come across it I tend to stock up. I've probably got a lifetime's worth stored away now considering I'm 60.
Good luck to you. I've been absent here for several months. Work projects and the silhouette shooting season have kept me busy.
Mike V.