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Joined: Dec 2004
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Sidelock
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Sidelock
Joined: Dec 2004
Posts: 81 Likes: 1 |
Hello to all
I know somebody here will know this-----
What EXACTLY does 12/1 mean on barrel flat of english guns??
WHAT does 13/1 mean
ditto 15/1
I realise it relates to the bore, 9" from the breech , but what are the sizes
How do I dertimine mathematically the 13/1 and the 15/1 sizes from the standard .729 of 12ga??
I THINK????? it relates to the number of those sized ball of lead to the pound?
Is this correct
Cheers
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Joined: Jan 2006
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Sidelock
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Sidelock
Joined: Jan 2006
Posts: 9,758 Likes: 460 |
This will help Vintage Guns: Collecting, Restoring, & Shooting Classic Firearms by Diggory Hadoke http://books.google.com/books?id=lvBk8df8PjUC&pg=PA139&lpg I think Daryl posted this some time ago 
Last edited by Drew Hause; 07/18/12 05:41 PM.
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Joined: Jan 2002
Posts: 866
Sidelock
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Sidelock
Joined: Jan 2002
Posts: 866 |
A little extra info. The fractionation of the whole numbers for bore diameter happened in 1887. Previously the number 12 covered bore sizes from .729 to .751. 13 covered .710 -.729 etc.
Better to keep your mouth shut and be thought stupid,than open it and confirm.
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Joined: Dec 2001
Posts: 12,743
Sidelock
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Sidelock
Joined: Dec 2001
Posts: 12,743 |
If you want to determine them mathamatically do the following for 12/1 as example. Add the dia of 12ga (.729") to the dia of 11ga (.751") then divide by 2 & drop any figures beyond 3 decimal places, do not round, just drop. IE .729" + .751" = 1.48/2 = .740" for 12/1. 10ga & larger have an extra division ie 10/1 & 10/2. For these you take 1/3 & 2/3 of the difference between the gauge & next larger one & again drop to 3 decimal places. Remember also even though a gauge is not in use these are all based on the next larger whole number gauge ie from 10 to 9, not 8 which is the next larger gauge in common usage. The formula for the Diameter(d) of any gauge with D as the diameter of 1 gauge is the cube root of the diameter of 1gauge cubed divided by the gauge number; thus d= 3√ Dcube/Ga. To exactly fit the British charts which extent all the way from onne down to 172.28 (.300") requires D to be carried to 6 decimal places. The best figure I have come up with which does fit all the way is D= 1.669285. I this case though the answer is "Rounded" to 3 decimal places. The in-betweens thus are truly averages & not strictly a mathamatical formula.
Remember all the inbetweens are larger than the gauge number & include 2 steps for 5Ga down through 10 ga & 1 step for gauges 11 down through 17ga. Gauges 4 & above & 18 & down are not divided.
Miller/TN
I Didn't Say Everything I Said, Yogi Berra
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