A 4 oz jar will do that barrel plus at least a couple more. How many strokes depends on how bad the barrel is. I use an old bronze brush that is worn out or a little too small for the bore. I then wrap large cleaning patches around the brush in the same direction as the rifling, enough to make it fit quiet tight. So tight, I have a hard time getting it down the barrel the first time. I smear on a thin coating of my polishing agent. Using a bore guide, and the gun in a solid rest, I push the brush/patch/polishing compound down the bore. I use a quality 1 piece rod. I need to use both hands on the rod, one pushing and one to keep the middle from bending. My patch, bush combination is about 2 1/2 inches long so use a bronze brush that is the long style. When I near the muzzle, I do not push it all the way out. I have found that if it goes all the way out and I try to withdraw it, the patch will just ball up and not come back through the bore. If done in this way, it will not hurt the crown either. As soon as the patch starts out the muzzle, I with draw it back down the bore. If I push too far, I unscrew brush/patch off and with draw the rod and reattach it and start another "stroke". As I work it back and forth, it gets easier to push it through. I keep an eye on it and every so often, I add a little more polishing compound. Just keep the patch damp with polishing compound. It does not take much. Your polishing compound will turn black. The black is the fine metal the polishing compound is taking off. Do not put on more than a thin coating, any more will just be shaved off in the bore guide. If the pushing gets too easy, I wrap another patch around the one I had and add more polishing compound. This usually tightens it up again. If it is too tight to get down the bore, then remove the last one you put on and work it with the old one. I like a lot of pressure on the bore sides, but even a little will work OK. I give it at least 100 full strokes. I then clean up every thing real well. I take the gun out to shoot it. I note if the accuracy starts to drop off quickly and there is a lot of copper fouling. If there is, I clean the copper fouling out and get the barrel spotless and repeat the regiment above. I do this until the barrel shoots with out undue copper fouling. I had a barrel (not a Handi) that I put at least 800 full strokes through. Most of the time 100 - 200 strokes is enough, but let your barrel tell you how many is enough. Some guys like to shoot their bore smooth. You do this by shooting a few rounds and cleaning it very well, shoot a few more rounds down the barrel, clean. They say it takes a few hundred shots to get to the point of shooting well. I think the polishing quickens this process. If done properly with a bore guide, I do not think it shortens the barrel life at all. Most barrels get worn out in the throat area first. The polishing compound will not wear out a throat, unless you do not use a bore guide to keep it centered as it enters the bore. BTW I do not do this if a barrel has been hand lapped at the barrel maker, the Handi does not fall into that category, only custom barrel makers do that. Good Luck and Good Shooting