Is there a list or chart showing rifle barrel bore diameters.
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Barrel bore diameters
- Thread starter theoldredneck
- Start date
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plmeek
40 Cal.
Modern muzzleloader rifle barrels usually have a bore diameter, as measured across the lands, consistent with their caliber designation. In other words, a .50 caliber rifle would have a bore ID of 0.500" and a .54 caliber barrel would have a bore ID of 0.540".
In the 17th, 18th, and first half of 19th century, there was a different system. A gun, whether smoothbore or rifle, was referred to by the size of ball it "carried". That size was usually designated by the number of balls it took to weigh a pound in the English system and the number of balls it took to weigh a livre in the French system. (A French livre weighed 489.5 grams while an English pound weighed 453.6 grams, so it was a slightly larger unit of measure.)
For example, the fur companies often ordered rifles to carry 32 balls-to-the-pound. The diameter of the balls in this case were 0.526" OD. The rifle bore ID has to be larger than the ball OD to allow for "windage" or patching material. Assuming windage of 0.015" would give a bore ID of 0.541" or a nominal .54 caliber in today's terminology.
Phil Meek
In the 17th, 18th, and first half of 19th century, there was a different system. A gun, whether smoothbore or rifle, was referred to by the size of ball it "carried". That size was usually designated by the number of balls it took to weigh a pound in the English system and the number of balls it took to weigh a livre in the French system. (A French livre weighed 489.5 grams while an English pound weighed 453.6 grams, so it was a slightly larger unit of measure.)
For example, the fur companies often ordered rifles to carry 32 balls-to-the-pound. The diameter of the balls in this case were 0.526" OD. The rifle bore ID has to be larger than the ball OD to allow for "windage" or patching material. Assuming windage of 0.015" would give a bore ID of 0.541" or a nominal .54 caliber in today's terminology.
Phil Meek
Thank you for the reply. Reason for asking would like to match bore diameter of rifled barrel as close as possible to smooth bore diameter. Use same ball and patch material for both barrels. Want to experiment with the difference between smooth and rifled barrel of same diameter. I understand the rifled barrel is more accurate. This is more to see other differences.
"Use same ball and patch material for both barrels."
No, no chart. Barrel makers describe the barrels they make.
Your goal will be difficult. Here is why:
Say your rifle (50 cal)has a .500 bore and 0.010" depth grooves. The diameter across the grooves will be 0.520". IF the lands and grooves are 50/50 width, you have an average bore + groove diameter of 0.510". You might use a .490" ball and a 0.025" patch, give or take. The grooves are necessary to fit all that down the barrel.
Your 50 cal, .500", smooth bore will be tight with that patch ball combo. So, you need to find someone to make you a .510", 51, cal smooth bore to go with your 50 cal rifle, if you want to use the same ball and patch.
Since your run of the mill 50 cal smooth bore will be an unrifled 50 cal barrel, you will need to change the patch or ball diameter. You could use a .480" ball same patch, or a 0.012" patch and a 0.490" ball.
No, no chart. Barrel makers describe the barrels they make.
Your goal will be difficult. Here is why:
Say your rifle (50 cal)has a .500 bore and 0.010" depth grooves. The diameter across the grooves will be 0.520". IF the lands and grooves are 50/50 width, you have an average bore + groove diameter of 0.510". You might use a .490" ball and a 0.025" patch, give or take. The grooves are necessary to fit all that down the barrel.
Your 50 cal, .500", smooth bore will be tight with that patch ball combo. So, you need to find someone to make you a .510", 51, cal smooth bore to go with your 50 cal rifle, if you want to use the same ball and patch.
Since your run of the mill 50 cal smooth bore will be an unrifled 50 cal barrel, you will need to change the patch or ball diameter. You could use a .480" ball same patch, or a 0.012" patch and a 0.490" ball.
Even a .50 cal rifle can be very different. A .50 May need a .490,495,.498,.500..505, a smooth .50 May not handle any of those sizes. A friend of mine built a .62 rifle thinkingg he could use the same ball as his fusil. His fusil needed a .595, his rifle needed a .610.
Some times old guns had funky measurements. A .62 shoots 20ball to apound, but 24 ball to the old french pound.
Sometimes old guns were measured in inches or fractions. The committee of safety called for guns of 3/4 inch, and reports of American rifles ddiscribe them as 7/16.
Some times old guns had funky measurements. A .62 shoots 20ball to apound, but 24 ball to the old french pound.
Sometimes old guns were measured in inches or fractions. The committee of safety called for guns of 3/4 inch, and reports of American rifles ddiscribe them as 7/16.
Thank you for your reply. I totally understand your explanation. Instead of asking here I should have just checked with barrel makers. Ask to find bore and groove diameter for 30 to 40 calibers. Then matched with smooth bore. This is really just a simple fun project to build and play with a couple of small bores.
As brought up the bore and groove diameters are different. The patch has to fit both. A smooth bore is a constant inside diameter. Patch thickness and ball diameter should equal bore diameter for good fit. I understand that for ball and patch to be same for both barrels inside diameter will not be exactly the same for both barrels. Knowing bore diameter of 32 or 36 caliber rifled barrel for example gives a starting point for smooth tube inside diameter to look for. The rifled barrel of a 32 or 36 caliber depending on bore and groove diameters will take ball and patch that can usually be figured out. Then playing with patch thickness and ball diameter a working combination is found. Smooth tubing comes in multiple inside diameters. Choosing a rifled barrel that runs nearest to a smooth tube that would work is reason for looking at rifle barrel bore diameter first. After looking at bore and groove diameters of some different barrel makers. Then looking at tubing sizes, calibers were narrowed down to a starting point. This is just an experiment to see how well I can get a small caliber smooth bore to shoot in relation to a rifled barrel of same basic caliber/size. After being bitten by the smooth bore bug and play with them a while this project came up. Thank You to all that replied.
An accurate post in every way...EXCEPT :shocked2: ..... in this crazy ml game, nothing seems to be the same anywhere.
Back in my early days in this game there were stories (and, of course being stories they had to be 100% accurate. :rotf: ) that the major manufacturers like Douglas and TC had varying bore diameters due to the wear on the cutters and buttons that rifled their barrels. Supposedly, as they wore the barrel diameter got slightly smaller with each barrel until the cutter was replaced and the next batch of barrels had larger bores. I dunno :idunno: how accurate any of that is. But, what I do know is often identical barrels or rifles next to each other might perform differently and like to be fed different combos of ball size and patch thickness. In my opinion, a stated caliber is simply a nominal reference to an approximate size. Ye gotta try it to know fer sure. Right now I am preparing for the new rifle Dave Person is building for me. I have two ball sizes and three different patches on hand to try. Hopefully, one of those will give me the groups I want. If not, I'll make adjustments and try again.
Back in my early days in this game there were stories (and, of course being stories they had to be 100% accurate. :rotf: ) that the major manufacturers like Douglas and TC had varying bore diameters due to the wear on the cutters and buttons that rifled their barrels. Supposedly, as they wore the barrel diameter got slightly smaller with each barrel until the cutter was replaced and the next batch of barrels had larger bores. I dunno :idunno: how accurate any of that is. But, what I do know is often identical barrels or rifles next to each other might perform differently and like to be fed different combos of ball size and patch thickness. In my opinion, a stated caliber is simply a nominal reference to an approximate size. Ye gotta try it to know fer sure. Right now I am preparing for the new rifle Dave Person is building for me. I have two ball sizes and three different patches on hand to try. Hopefully, one of those will give me the groups I want. If not, I'll make adjustments and try again.
Aren't old TC's button barrels? No cutter involved? Thus the shallow rifling?
Anyway, sure, you'd have to slug the barrel and see what you actually have. I was just giving a guess based on averages using easy to figure math.
So, after slugging the rifle and determining the bore and groove diameters, as well and the width of lands and grooves one could make a guess on what smooth bore size to pick.
If I was actually going to do this I would ask Bobby Hoyt.
Anyway, sure, you'd have to slug the barrel and see what you actually have. I was just giving a guess based on averages using easy to figure math.
So, after slugging the rifle and determining the bore and groove diameters, as well and the width of lands and grooves one could make a guess on what smooth bore size to pick.
If I was actually going to do this I would ask Bobby Hoyt.
Yes, no, maybe and sometimes. Depending on who you ask. I believe most were button rifled but, at times, outside vendors provided barrels to TC.
