Thanks to all of you for your suggestions. I feel certain that the problem is all about fowling accumulating after several firings which in my case was 5.
Fouling won't normally build up in the breech unless it was knocked off of the barrel walls by "swabbing" with multiple strokes while cleaning between shots.
I have my doubts that the suggestion of perhaps some protective grease being the cause of the problem. I had all the steel parts blued which required complete degreasing.
You are probably right however, if you poured oil down the bore to protect it and you didn't clean it out before firing the gun, the oil can contaminate the powder that contacts it resulting in the small hole between the breech and the nipple clogging up.
One fellow asked my procedures on loading. After placing a pre-measured amount of 2F GOEX powder into the barrel. Then the ball is rammed home after first placing a cotton patch which is impregnated with WONDER LUBE over the muzzle, then placing the ball over the patch. Push the ball and patch with a starter then finish with ramming it home with the ramrod.
From the beginning it appeared the problem was all about fowling since placing a small amount of 4F powder into where the nipple goes and then replacing the nipple the rifle fired every time.
I agree. If you are leaving the previously fired cap on the nipple or you are leaving the hammer down so it rests on the nipple while you are loading the next shot, the blockage of the nipple hole will prevent the loose powder from being blown back thru the breechplug to end up right below the nipple.
When loading, always make sure the hammer is at half cock and the nipple is free of cap remnants.
I was not aware that there are nipples available which allow for placing some 4F powder in it before placing a cap in the nipple. That seems to be a quick fix for the problem w/o having to stop and clean the rifle after each shot. Please provide either the name of this special nipple and if possible a vendor.
There are no nipples designed for putting 4F powder into them before placing a cap on it. There often is a slightly enlarged hole above the small hole at the bottom of the nipple but it is intended to allow all of the flame from the cap to enter the nipple. It was not designed to serve as a priming location.
I had considered getting one of those HOT SHOT nipples but am not certain of the thread size. It appears it might be 6 X 1 mm but thought it might not be a metric thread. Does anyone know if it would be a metric thread.
If your gun was made in Spain, it probably has a M6X1 thread. Before spending the money for a new nipple, take your existing nipple to a local hardware or auto parts store. They will be able to tell you what the threads are.
About modifying the jag. Just to be certain is a jag a cork screw type device used to hold cleaning patches? Does the suggestion of modifying it involve twisting it to a smaller size so that the fit down the bore does not push the fowling down the barrel but allows the patch to pass the fowling on the down stroke and then cling to it on the up stroke. Am I reading this correctly.
The jag being referred to is not the corkscrew style. It is the common grooved brass jag that was turned down to reduce its size. If the wiping patch being used is thinner than a shooting patch this is usually not necessary.
While talking about cleaning a barrel what have you all found works best? I usually use very hot water in conjunction with a strong laundry detergent such as WISK. First remove the nipple and the small screw next to the nibble. Then place that end in a hot bucket of water. Squirt some WISK down the bore followed by a bore swab which is usually used to clean a shotgun bore. After removing the crud squirt some WD-40 to displace the water followed by running some patches in the bore and then spraying a gun oil into the barrel.
Sounds pretty good to me. Just a suggestion though.
After oiling the bore, store the gun with the muzzle pointing down. That will keep any excess oil from running down into the flame channel hole in the breech where it can pool and cause trouble.
There is a material known as BORE BUTTER. Is that any good or is there something better.
Bore butter is OK for lubing patches. There are about 102347 other lubes that can be made at hole for far less money and will work just as well.