First of all the rifle was a Spanish Jukar 54 caliber flintlock and the rust/corrosion was so bad that there was not much left of the lands. I didn't think it was worth sending the barrel to Bobby Hoyt, which I have done in the past. So I thought a little experimenting was in order.
The crank shaft paper I started out with was 58 grit so it removed what was left of the lands without any problem. To finish up I switched to 100 grit then Scotch Brite pads for a smoother finish.
Yes, it took me quite a long time with multiple passes both from the muzzle and the breech. I had pulled the breech plug. I was very careful to use a steady stroke both down & back swapping the ends with every in & out stroke. I really can't tell how long it took to get to the groves, as I would work on it in my spare time over a month probably. Before anyone asks when I was finished for the day, I ran an oil soaked very tight patch on a jag down the bore to prevent it rusting and to feel for tight or loose sections. When I was using the hone I used Tap Magic as a cutting oil.
When I was satisfied with the final passes I measured the bore at the muzzle and it was 0.725 so basically a 12 ga. Not happy with just knowing the muzzle diameter, being a blacksmith and regularly forging things to the thickness of a well worn shilling I forged a button to fit snugly in the bore at the breech, it measured 0.736 and I could turn it without any tight or loose spots. I drilled and tapped the button for a machine screw that would fit my steel range rod. Ran the button from the breech turning it every inch to see if the bore was concentric and was satisfied that it was close enough. the button got tight about 2 & 1/2 inches from the muzzle. I thought about using the hone to open it up, then why, I basically had a back bored 12 gauge with a choke. Even though the barrel walls were a little thicker it pointed pretty good but didn't swing as fast as the original Fowler's I have restored.
Funny end to that gun. I thought about using it for turkey hunting. I was at the range to do some test firing. I have a good assortment of felt wads and over powder & shot cards. In my other shot guns, I use an equal amount of powder and shot by volume. I started with 70 gr of Goex ffg powder primed with ffffg and an equal volume of # 4 lead shot. Placed a turkey target out at 40 yards. The pattern was so/so. I increased the powder to 80 gr and equal volume of shot. That pattern was acceptable to me with about 8 pellets in the head & neck area.
While I was out hanging another target someone pulled up and got out of his truck and walked up to the firing area, walking back, I noticed he was looking at the gun and target. I recognized him from some of our muzzle shoots at the range. While I was loading it up he asked about the interesting shotgun and I gave him the cliff notes about it and I accomplished it without $30,000 worth of tooling.
He seemed so interested I asked him if he would like to shoot it. Silly question I know, I also knew he was familiar with muzzleloaders so I handed it to him and the priming flask. He stepped up to the firing line, primed it and steady as rock took aim and boom. He handed it back and said he would go and get the target. When he got back we compared the targets and his had a little tighter spread definitely a dead turkey.
While I was at the loading bench he asked how it shot round balls. It just so happened I had balls & patches that would fit it. He took a regular rifle target out and put it up. When he returned I loaded it up, steped up to the firing line, primed and boom. We could see the bullet hole, a little off to the right and at 2 o'clock. I loaded again, handed it to him with the priming flask. He walked up to the line and again steady as a rock boom. He laughed and said Kentucky windage the shot was 12o'clock right above the ten ring. I told him he was a lot steadier than I so try a couple more shots. This time he loaded it and that shot was in the ten ring, after a couple of more shots which all grouped in the ten ring, he asked me if I would sell it.
He was telling me he deer & turkey hunted but didn't have a flintlock. I told him to make me an offer, I went home with $300, when Jukar's were only selling for about $100, how could I resist, because I no longer hunted and if I decided to go hunting, I had enough guns to choose from.
The last time I saw him at a shoot he told me he took 2 nice toms and an 8 point buck with it. It felt good to make someone happy.
OH and by the way a friend who worked for Wilson Combat took the barrel and using their gauges, confirmed my measurements and said good job. Would I do that again, oh heck no, but I still use the hone to remove rust from any smoothbore I get that needs it, since the Jukar I've used it twice but with Fine paper.
Curious as to what you found the bore diameter to measure at the breech and muzzle
Must have.
To make a smoothbore you need to drill out the rifleing. This is best done with a piloted drill. The rifling usually sets up a harmonic vibration that ruins the finish. That needs to be tamed. Then once the hole is round it need to be reamed. Both are done using a lathe, special tools and coolant-lubricant under pressure. The speed and feed is important to getting decent result.
Hoyt does this work all day long. He will do it right.
