Bore size of Shotgun, Rifles & Handguns

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Post by ARMARIN » Sat Mar 30, 2019 4:50 pm

The bore size of Shotgun, Rifles & Handguns
Some basic but useful information:


Caliber is not dimensional measurements of a ROUND. It is rather a measurement of a BULLET !
The military is very straightforward when it comes down to the application of a round to intended target, their terms of caliber include the dia of projectile + the length of case and barrels. A military personnel can make it more clear.

Caliber and Bore are more of the same thing less technically and for all of us

and however Technically:
Bore is(measurement) related to a Barrel OR a Weapon which is bearing that specific BORE barrel.
Bore measurements are taken from (see rifling Lands/Grooves) a Land to a Land inside a barrel. It is something related to a barrel/weapon but not bullets.
Caliber measurements are taken from Groove to Groove inside a barrel, which is referred as groove diameter, and which is equal to the Caliber of Bullet used in that barrel.

now for an EXAMPLE please consider the following:
a 30 caliber rifle uses a .308" dia bullet. Each groove of the rifling is .004" deep. The two opposing grooves measure .008" and the distance across the lands is .300". It all adds up to .308.

The caliber of a weapon? :-
When we talk of Caliber of a weapon, it means the land to land diameter or BORE of weapon actually sometimes like in case of a 30-06 weapon, where BORE is .300 or .30 and Bullet itself is .308 inch.

In case of AK47, known as a 7.62 or .30cal weapon, where the BORE of weapon is 7.62mm and bullet diameter itself is 7.92mm

Weapon calibers are based on their BORES i.e. land to land measurements which is always less than the CALIBER of bullet used in it. Also sometimes a weapon caliber is same as that of bullet used in it, e.g .308 commercial rifle and also 7.62*51mm NATO, here the actual bullet is 7.62mm, BORE must be less that this. But unlike Springfiled we still call the weapon by its ACTUAL BULLET DIA or Groove DIA!
I like metric systems, like all jarheads...

Moreover, Caliber representation is done with respect to INCHES ! more specifically
though Metrics system (mm) is another way to measure the BORE/Caliber of Weapon(loand to land measurements) or Caliber of a Bullet(bullet diameter represented in INCHES).

(From the book by Walther Lampell - JAGDBALLISTICS-)


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Post by jimg11 » Thu Sep 17, 2020 12:23 am

We must remember that for every rifle, pistol, revolver, and shotgun there are only 2 sizes of ammunition. Do you know what they are?? The right size and everything else is the wrong size. There is only one right size which is the one that the rifle, handgun or shotgun was designed and manufactured to have it fit. All the other sizes are the wrong size for that particular rifle, handgun or shotgun. Almost all commercial guns have the right size stamped on the barrel or somewhere else. There have been well over 1500 wrong size cartridges for your gun made in the last 160 years or more. Make sure you have the right size cartridges for your gun.
Firearms Safety is No Accident. Jim

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