Is the barrel hole of a gun the same size as the bullet?
- Thread starter LookAtYou
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The part that says bore is also known as land. Groove is still groove.I will add this to the Thread simply because some folks forget and some do not yet know.
View attachment 984808
Both my .30'06 and my .308Win rifles sport the same diameter bullets, but they are both .30 caliber rifles, referring to the Bore diameter.
Grooves for these are usually about .004" deep, with that on either side, .008" more than the .300" bore, and so .308".
Clear as mud.
As others have indicated, for reloading .38/.357 (both normally have a .357 groove diameter) you would usually use .357 jacketed bullets and, .358"-.359" lead (to assure a good seal).
Enjoy!
Archie
Member
To speak to your initial question, it depends. It depends on usage of the terms and actual measurement in specific circumstances.
Very seldom is a cartridge or bullet exactly the same as advertised. For instance, a .32 pistol (in the United States) is typically .312 inches or thereabouts. A British .303 round and bullet is pretty much .312 inches. There are many others. However, bullets are sold usually with the exact - as close as can be determined - diameter, and are often marked with the popular name of the cartridge or firearm.
The specific question of "are the bullets the same size as the bore" also depends on several factors.
Some are intentionally undersized. Black Powder muskets were normally supplied with undersized balls to facilitate jamming a projectile down a fouled barrel. At the same time, one used a 'patch', either a cloth or paper wrapper to somewhat seal the bore. Later the Minie (named after the inventor, Claude-Étienne Minié) ball, which was actually a modern looking pointy bullet with a hollow base was developed for muzzle loaders. It was undersized for ease of loading, and the hollow base - under the pressure of the burning powder - filled out the bore.
One notes (some, not all) .38 Special wadcutters are made hollow based for the same reason. They're not undersized, but it works well for extreme accuracy while target shooting.
There are manufacturing tolerances to be considered. As noted prior, 9mm pistols (chamber for the 9mm Luger, Parabellum or such) have been found with bore diameters ranging from .354 inch to .359 inch. There were mainly wartime guns turned out in a hurry. Actual ammunition is supposedly .355 inch in outside diameter, but the ammunition varies as well. Nor did the outfits who made guns with .359 inch barrels 'fit' the ammunition they made to the guns. But as also correctly mentioned, pretty much all the ammo served 'acceptably' for pretty much all the pistols. Probably a high sized bore pistol would not score impressively with low sized bullets on a bullseye match. But none of those mentioned were intended for 'match use'.
The standard for shooting lead bullets in revolvers has always been to size the bullet about .002 inches wider than the groove diameter. (See the diagram above for 'land and groove' diameter. It is excellent.) However, in a revolver, all bullets are squished through the neck of the cylinder. Then the bullet expands a bit when passing through the cylinder/barrel gap and is then squished down again when entering the forcing cone of the barrel. So no matter what size the bullet was to start, it is now different and likely the size of the groove diameter of the barrel finally. Pistol barrels likely have slight differences in the full distance as well. If the bullet is affected by the muzzle section of the pistol, it will fly true. However, a 'loose' fit will allow gas to escape the muzzle velocity will be lessened.
Usually, handgun pressures are low enough not to cause problems with any of this. Rifles are much higher pressured.
Rifle barrels are much like pistol barrels. But manufacturing tolerances exist and can cause sloppy fit and loss of accuracy and power in some cases.
So to answer the question as initially posed, "Is the barrel hole of a gun the same size as the bullet?"
Yes, it is supposed to be.
No, not usually in practice. Close enough for me and the girls I date.
Very seldom is a cartridge or bullet exactly the same as advertised. For instance, a .32 pistol (in the United States) is typically .312 inches or thereabouts. A British .303 round and bullet is pretty much .312 inches. There are many others. However, bullets are sold usually with the exact - as close as can be determined - diameter, and are often marked with the popular name of the cartridge or firearm.
The specific question of "are the bullets the same size as the bore" also depends on several factors.
Some are intentionally undersized. Black Powder muskets were normally supplied with undersized balls to facilitate jamming a projectile down a fouled barrel. At the same time, one used a 'patch', either a cloth or paper wrapper to somewhat seal the bore. Later the Minie (named after the inventor, Claude-Étienne Minié) ball, which was actually a modern looking pointy bullet with a hollow base was developed for muzzle loaders. It was undersized for ease of loading, and the hollow base - under the pressure of the burning powder - filled out the bore.
One notes (some, not all) .38 Special wadcutters are made hollow based for the same reason. They're not undersized, but it works well for extreme accuracy while target shooting.
There are manufacturing tolerances to be considered. As noted prior, 9mm pistols (chamber for the 9mm Luger, Parabellum or such) have been found with bore diameters ranging from .354 inch to .359 inch. There were mainly wartime guns turned out in a hurry. Actual ammunition is supposedly .355 inch in outside diameter, but the ammunition varies as well. Nor did the outfits who made guns with .359 inch barrels 'fit' the ammunition they made to the guns. But as also correctly mentioned, pretty much all the ammo served 'acceptably' for pretty much all the pistols. Probably a high sized bore pistol would not score impressively with low sized bullets on a bullseye match. But none of those mentioned were intended for 'match use'.
The standard for shooting lead bullets in revolvers has always been to size the bullet about .002 inches wider than the groove diameter. (See the diagram above for 'land and groove' diameter. It is excellent.) However, in a revolver, all bullets are squished through the neck of the cylinder. Then the bullet expands a bit when passing through the cylinder/barrel gap and is then squished down again when entering the forcing cone of the barrel. So no matter what size the bullet was to start, it is now different and likely the size of the groove diameter of the barrel finally. Pistol barrels likely have slight differences in the full distance as well. If the bullet is affected by the muzzle section of the pistol, it will fly true. However, a 'loose' fit will allow gas to escape the muzzle velocity will be lessened.
Usually, handgun pressures are low enough not to cause problems with any of this. Rifles are much higher pressured.
Rifle barrels are much like pistol barrels. But manufacturing tolerances exist and can cause sloppy fit and loss of accuracy and power in some cases.
So to answer the question as initially posed, "Is the barrel hole of a gun the same size as the bullet?"
Yes, it is supposed to be.
No, not usually in practice. Close enough for me and the girls I date.
ponchh
Member
Bullet vs barrel and designations by Paul Harrell. Your question is answered in the first 5 minutes
CapnMac
Member
About 6 different GSW Trauma studies from urban ERs have agreed on the figure.
The Pathologists also concur in the number.
That excludes DOAs in many cases. There's statistical argument on how to account for that in the numbers.
DocRock
member
I like Paul.
I am distressed by his lack of Latin. "Magnum" is the Latin word for "Great" (we need not address gender or case at this time).
Does that account for the firearm type or is it mostly pistols? I don’t know why it seems high to me. My uncle survived a torso hit with a 7mm Mag from about 6’ away.
CapnMac
Member
The ER reports run about 1:100 GSW are rifle (or greater than handgun)--that hoary old FBI stat is correct, blunt objects, pipes, and the like are used more often than rifles in crimes.
Why it seems high may just be bleed-over perception. We have been shown too many people on film & tv not surviving any GSW, which creates a preconceived notion that can be hard to shake. Maybe. Perhaps.
A previous Pope was shot like 11 times from about 2 meters with 9x19 FMJ, and lived long after. We just don't hear about people surviving GSW, but they do.
Much of that is 'modern' medicine. People don't die of infection, except in very rare cases. Microsurgical repairs are common and widespread. The one limitation the docs have is in replacing lost tissue.
230RN
2A was "political" when it was first adopted.
....and then there are the shotgun bores.
And then there are the "three line" calibers.
Oh, and the naval guns (cannons), many of which are 54 caliber.
Ooo! Ooo! Then there's Mons Meg.
"Heloooo! Anybody home?".. home?.... home.?.....home?....
(That's the name of the cannon, not the lady.)
Terry, 230RN
REFs:
https://www.thehighroad.org/index.php?threads/my-three-line-rifle.830330/
https://en.wikipedia.org/wiki/5-inch/54-caliber_Mark_16_gun
https://en.wikipedia.org/wiki/16-inch/50-caliber_Mark_7_gun
https://duckduckgo.com/?q=meg+mons&t=h_&ia=web
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Jim Watson
Member
You might ought to explain to the OP that "caliber" in the Navy meant the length of the gun barrel.
lysanderxiii
Member
rabid wombat
Member
Most Navy guns were identified by bore and barrel length. For example, a 3” 50 had a bore of 3” and a barrel length of 50 * 3”, or 150 inches. A 16” 50 works the same way. A 16” bore and a barrel length of 50 * 16”, or 66’ 8”. No idea why 50 “calibers” was common, but canon crackers can answer that.
https://en.wikipedia.org/wiki/16-inch/50-caliber_M1919_gun
A 3”50 brass:
For giggles:
Common method is push a greased lead piece - egg sinkers work well - through the barrel then measure lead piece. Works well on old mil surpluses with unknown bore diameters.
230RN
2A was "political" when it was first adopted.
Noooo, I did not want to explain it. I figured the THR-ers would cover it pretty well. Mention of navel ordinance always generates lots of fun. 'Sides, that's why I added the REFs.
I know I'm going to get in trouble for this, but here goes:
Fifty calibres seems to be the best barrel length for the usual loading density (powder type, chamber to barrel volume, projectile weight, rotation bands, etc, etc. etc.) For example, a long time ago I was told that the ideal barrel length for "the .22" standard velocity was eighteen inches. (I forgot which .22 -- LR or short or long.) Beyond that length the bullet started to lose velocity in the barrel, shorter than that, the bullet had not yet accelerated as much as possible. But with all the variations on bullet weight and style in "the .22" nowadays, all bets on that are off.
The ordnance department does a lot of experimenting with variables and often settles on similar things for other similar things. D'ja ever notice that the .50BMG, .30-'06, and .223 Remington (5.56 NATO) cartridge cases are almost identical in shape to each other. Not sure, but I think the 20mm shell is the same story. So around 50 calibres seems to be good enough for the general cannon length and "loading density,"
That's the way I see it, anyhow. Contrary views are welcome.
Terry, 230RN
Edited for Typos
I know I'm going to get in trouble for this, but here goes:
Fifty calibres seems to be the best barrel length for the usual loading density (powder type, chamber to barrel volume, projectile weight, rotation bands, etc, etc. etc.) For example, a long time ago I was told that the ideal barrel length for "the .22" standard velocity was eighteen inches. (I forgot which .22 -- LR or short or long.) Beyond that length the bullet started to lose velocity in the barrel, shorter than that, the bullet had not yet accelerated as much as possible. But with all the variations on bullet weight and style in "the .22" nowadays, all bets on that are off.
The ordnance department does a lot of experimenting with variables and often settles on similar things for other similar things. D'ja ever notice that the .50BMG, .30-'06, and .223 Remington (5.56 NATO) cartridge cases are almost identical in shape to each other. Not sure, but I think the 20mm shell is the same story. So around 50 calibres seems to be good enough for the general cannon length and "loading density,"
That's the way I see it, anyhow. Contrary views are welcome.
Terry, 230RN
Edited for Typos
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Archie
Member
When a 'length' is mentioned in terms of 'calibers' (barrels, bullets and seating depths are specified in this manner, not used as much anymore) the term caliber is the bore diameter. The bore diameter of the arm under discussion.
For instance, I used to have an acquaintance who was a gunner in the U. S. Navy. He made reference to a "5 inch 38". I thought he was talking about an older Smith & Wesson revolver, chambered in .38 Special with a five inch barrel. No. The Naval arm he mentioned had a five inch bore (actual diameter was likely a couple thousands off) with a barrel thirty-eight times as long as the bore, or thirty eight times five inches. That's 190 inches or nearly sixteen feet long.
Another, riflemen (hunters, mostly) used to mention "... a bullet of three or four calibers ..." which meant a bullet of three or four time the diameter of the bullet. This would obviously vary with diameter, but would indicate a 'heavy' bullet or one with suitable sectional density.
And loading manuals used to suggest a seating depth of at least one caliber. Or at least as deep as the diameter of the bullet. Which means a larger caliber bullet should be seated deeper than a small caliber bullet.
230 RN spoke of "best barrel length" in relation to powder charge and loading density. The concept of 'overbore' has been long discussed and is too long for this thread, but interesting.
For instance, I used to have an acquaintance who was a gunner in the U. S. Navy. He made reference to a "5 inch 38". I thought he was talking about an older Smith & Wesson revolver, chambered in .38 Special with a five inch barrel. No. The Naval arm he mentioned had a five inch bore (actual diameter was likely a couple thousands off) with a barrel thirty-eight times as long as the bore, or thirty eight times five inches. That's 190 inches or nearly sixteen feet long.
Another, riflemen (hunters, mostly) used to mention "... a bullet of three or four calibers ..." which meant a bullet of three or four time the diameter of the bullet. This would obviously vary with diameter, but would indicate a 'heavy' bullet or one with suitable sectional density.
And loading manuals used to suggest a seating depth of at least one caliber. Or at least as deep as the diameter of the bullet. Which means a larger caliber bullet should be seated deeper than a small caliber bullet.
230 RN spoke of "best barrel length" in relation to powder charge and loading density. The concept of 'overbore' has been long discussed and is too long for this thread, but interesting.
lysanderxiii
Member
The reason the length of tubes is given in "calibers" is the interior ballistics equations all wind up dealing with the ratio of bore/length which is the definition of "caliber".
The US Navy settled on 50 caliber as a popular length due to the requirement that the tube be balance, the weight of the breech block is fixed for a constant bore but the height of the pivot point above the deck (or rotating platform) gets higher as the tube gets longer due the the balance point moving down the length of the tube as the overall length increases. If the pivot gets to high manual loading becomes difficult at low elevation, as the loader has to lift the projectile or cartridge over his head. For the big stuff, 8 and 16 inch guns, you have structural limitations on the height of the pinion.
Newer automatic loading mounts do not have this height restriction for loading, so you have the 3"/62 and the 5"/54.
The Panther tank gun, the 7.5 cm Kampfwagenkanone 42, was a 70 caliber gun.
EDIT:
Oh, one last thing and tube length in calibers: the length referenced is the bore length, not the overall length from muzzle to breech.
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CapnMac
Member
Well, some are, typically with a 5" bore. it's not a requirement.
Yeah, there's a sweet spot around 50 calibers.
A common deck gun was the 5"/51 which had a range out to about 12 miles. The follow on five inch was the famous 5"/38, which had a shorter barrel, deliberately, so as to speed how quickly it could be brought to maximum elevation (85º) as it was a dual-purpose gun meant to engage surface targets out to 17,000 yards, or aircraft targets to 37,000MSL. That round is a 127x680R, for cartridge nerds.
This was replaced by the DP 5"/54. There was an experimental 5"/61 but it was not enough better to replace the current 5"/54s.
Until the later 30s, 16" rifles were in the 40-45 caliber length, which was due to coping with "droop."
Another common deck gun was the 3"/25, which was used through WWII. It was not a great DP gun, but, the weight and muzzle clearance radius meant it could be fit to a large number of vessels.
In European notation, "L" is often used in place of "caliber." When Bofors improved their 40mm gun in the 50s, it went from the L60 to the L70, adding 400 (10 x 40)mm to the barrel which well matched going from 40x311R to 40x365R (the earliest Bofors was the L43 using 40x311R).
Not a Redleg, just started life as a GunnO before becoming OppO.
230RN
2A was "political" when it was first adopted.
According to my memory of Hatcher, the French discovered that putting strips of tin (Sn) foil in the powder much reduced the jacket fouling and after a while, everyone just put the tin in the copper as a jacket alloy for the same result.
Copper fouling does not in and of itself ruin the bore. Most fouling occurred near the muzzle, not where the pressure is greates or the gas hottest near the chamber, but where the bullet is fastest. It was the very greatest nuisance since removal involved filling the barrel with nasty solvents to chemically remove it, usually with "ammonia dope." Los of recipes were tried and can still be found. Great care had to be taken with some types, where if air got in with the dope, it would corrode the barrel steel at that point.
Terry, 230RN
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