You don't say what type of firearm you are referring to. The British Pattern 1853 Enfield was .577 caliber while the U.S. Springfield Model 1855 was a nominal .58 caliber. Both of these arms were rifled muskets designed to shoot the Minié ball.
Caliber designations were getting real confused around the middle of the 19th century. Previously, bore size was referred to by ball size as in the number of balls to the pound. A gun that carried a ball 28 to the pound was nominally a .58 caliber in modern terms. The ball diameter is 0.550" for 28 balls-to-the-pound. Adding 0.03" for windage (allowance for patch material and fouling build-up) gives a bore diameter of 0.580". This was the standard NW trade gun bore size for the Hudson Bay Company. Military smoothbore muskets had more windage, on the order of 0.05", while civilian rifles generally had less windage in the range of 0.01".
When guns were developed to shoot bullets without patch material such as the Minié ball and Colt's cap & ball pistols, we start seeing the use of the term "caliber" to represent the ID of the bore--not the ball OD. But this was new territory for gun manufacturers, and there weren't any standards. Minié balls were generally close to the land-to-land bore diameter. Colt's .44 caliber cap & ball pistols shot balls with OD's of 0.451" while his .36 caliber pistols used 0.375" balls. These were the nominal groove-to-groove diameters of the barrels. The land-to-land diameters were closer to the designated calibers.
For muzzleloaders, when guns were designed to shoot balls with patches, either cloth or paper, the ball OD is smaller than the bore ID (land-to-land if a rifled barrel). For muzzleloaders designed to shoot bullets without patching material in rifled barrels, the bullet OD is usually equal to or larger than the bore ID (land-to-land).
Eventually, this gets even more confusing in the cartridge era as the term "caliber" switched from being a measure of the land-to-land ID to being a measure of the groove-to-groove ID.
You don't say what type of firearm you are referring to. The British Pattern 1853 Enfield was .577 caliber while the U.S. Springfield Model 1855 was a nominal .58 caliber. Both of these arms were rifled muskets designed to shoot the Minié ball.
Caliber designations were getting real confused around the middle of the 19th century. Previously, bore size was referred to by ball size as in the number of balls to the pound. A gun that carried a ball 28 to the pound was nominally a .58 caliber in modern terms. The ball diameter is 0.550" for 28 balls-to-the-pound. Adding 0.03" for windage (allowance for patch material and fouling build-up) gives a bore diameter of 0.580". This was the standard NW trade gun bore size for the Hudson Bay Company. Military smoothbore muskets had more windage, on the order of 0.05", while civilian rifles generally had less windage in the range of 0.01".
When guns were developed to shoot bullets without patch material such as the Minié ball and Colt's cap & ball pistols, we start seeing the use of the term "caliber" to represent the ID of the bore--not the ball OD. But this was new territory for gun manufacturers, and there weren't any standards. Minié balls were generally close to the land-to-land bore diameter. Colt's .44 caliber cap & ball pistols shot balls with OD's of 0.451" while his .36 caliber pistols used 0.375" balls. These were the nominal groove-to-groove diameters of the barrels. The land-to-land diameters were closer to the designated calibers.
For muzzleloaders, when guns were designed to shoot balls with patches, either cloth or paper, the ball OD is smaller than the bore ID (land-to-land if a rifled barrel). For muzzleloaders designed to shoot bullets without patching material in rifled barrels, the bullet OD is usually equal to or larger than the bore ID (land-to-land).
Eventually, this gets even more confusing in the cartridge era as the term "caliber" switched from being a measure of the land-to-land ID to being a measure of the groove-to-groove ID.
Just a thought that I’m sure has been noticed by others.( I like to think of it as my own but know it isn’t). We see so many .36,.44/45, .58 and 12 gage. Just a few hundredths of an inch below 3/4 of an inch as to make it functionally the same.You don't say what type of firearm you are referring to. The British Pattern 1853 Enfield was .577 caliber while the U.S. Springfield Model 1855 was a nominal .58 caliber. Both of these arms were rifled muskets designed to shoot the Minié ball.
Caliber designations were getting real confused around the middle of the 19th century. Previously, bore size was referred to by ball size as in the number of balls to the pound. A gun that carried a ball 28 to the pound was nominally a .58 caliber in modern terms. The ball diameter is 0.550" for 28 balls-to-the-pound. Adding 0.03" for windage (allowance for patch material and fouling build-up) gives a bore diameter of 0.580". This was the standard NW trade gun bore size for the Hudson Bay Company. Military smoothbore muskets had more windage, on the order of 0.05", while civilian rifles generally had less windage in the range of 0.01".
When guns were developed to shoot bullets without patch material such as the Minié ball and Colt's cap & ball pistols, we start seeing the use of the term "caliber" to represent the ID of the bore--not the ball OD. But this was new territory for gun manufacturers, and there weren't any standards. Minié balls were generally close to the land-to-land bore diameter. Colt's .44 caliber cap & ball pistols shot balls with OD's of 0.451" while his .36 caliber pistols used 0.375" balls. These were the nominal groove-to-groove diameters of the barrels. The land-to-land diameters were closer to the designated calibers.
For muzzleloaders, when guns were designed to shoot balls with patches, either cloth or paper, the ball OD is smaller than the bore ID (land-to-land if a rifled barrel). For muzzleloaders designed to shoot bullets without patching material in rifled barrels, the bullet OD is usually equal to or larger than the bore ID (land-to-land).
Eventually, this gets even more confusing in the cartridge era as the term "caliber" switched from being a measure of the land-to-land ID to being a measure of the groove-to-groove ID.
I'm going to hope I can work up a doable load for a PRB. We'll see.
Based on my own limited play, that's possible if you go with a tight patch/ball combo then hold your charges down in the 60 grain range. I can't claim that's a formula for all shallow groove barrels because of my experience with only a handful of rifles, but so far it's worked with the ones I've played with.
Biggest issue with fit is the ram capabilities of thin metal ramrod. May need to get a range rod.
Before I sold my Armi Sport .577 Enfield musket, I tried shooting .577 minie balls out of it. I couldn't hit the broad side of a barn. Then I tried .58 minie balls and I could at least get it on a cardboard target.
I have 2 Armisport muskets- a Richmond carbine and a Richmond 3-Band. The carbine measures .579" and the 3-Band measures .577". My Zoli Zouave measure .581".
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