Author Topic: ...Bore Size...  (Read 2928 times)

Offline Cades Cove Fiddler

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...Bore Size...
« on: February 12, 2017, 06:58:27 AM »
.......Gentlemen.... Cannot find my bore gauge .....is there a chart that shows the land-to-land measurements and equivalent  calibre size... ?? ... made a heavy  paper form in shape of bore gauge and marked with a fine point pencil .... measures at 7/16 or 10mm.  .... any ideas appreciated.......Thanx.. ::) :-\

Offline Clark Badgett

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Re: ...Bore Size...
« Reply #1 on: February 12, 2017, 07:55:45 AM »
7/16" is .4375" and 10mm is .3937" lots of difference in those sizes.
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Offline WadePatton

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Re: ...Bore Size...
« Reply #2 on: February 12, 2017, 10:03:14 AM »
7/16" is .4375" and 10mm is .3937" lots of difference in those sizes.

Yeah, I associate 10mm with 3/8" or .375".

7/16 is a bunch bigger. Can't be both.
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Offline Cades Cove Fiddler

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Re: ...Bore Size...
« Reply #3 on: February 12, 2017, 06:11:59 PM »
.... ;D ::)...Closer to 11 mm.  ....my old eyes not so good at reading small marks....Thanx....Guess I best order another bore gauge.....!!!

ron w

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Re: ...Bore Size...
« Reply #4 on: February 12, 2017, 06:48:33 PM »
not an expert here, but proficient with numbers, guns in general and precision machine work........03937(1mm.) x 11=.43307 probably .43 dia. maybe less (.42) further down the bore, given a little muzzle wear depending on age and metal composition of the barrel, from the ram rod/cleaning rod. you don't say how old the barrel is, but it's not uncommon for a wrought iron barrel to show that much wear at the muzzle. otherwise, if you just want to find out what size ball to use, try to get a 10mm and an 11mm. ball and see which is tight or tighter and how the fit is as (the ball) goes down the barrel. as said... there's lot's of difference between 10 and 11 mm. as far as bore size/ball size goes. a 10mm. ball will fall right down an 11 mm. bore and an 11mm. ball won't even begin to enter a 10 m. bore..... (you could also use the shank ends of a 10 and an 11 mm. drill bit, for that matter).   I wouldn't necessarily trust just a bore gauge at the muzzle of an old gun. if the barrel's been coned at all, your gauge might not give an actual "bore size" further down past the coning.

Offline Daryl

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Re: ...Bore Size...
« Reply #5 on: February 13, 2017, 10:48:56 PM »
Buy a set of dial callipers. The Hodgdon Calipers are good ones - I like mine.
« Last Edit: February 13, 2017, 10:49:28 PM by Daryl »
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"a gun without hammers is like a spaniel without ears" King George V

Offline Clark Badgett

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Re: ...Bore Size...
« Reply #6 on: February 14, 2017, 01:16:02 AM »
7/16" is .4375" and 10mm is .3937" lots of difference in those sizes.

Yeah, I associate 10mm with 3/8" or .375".

7/16 is a bunch bigger. Can't be both.

A good quick and easily memorable English to metric reference is 9mm is close to .36 and 10mm is close to .40. That will get ya close
« Last Edit: February 14, 2017, 01:18:24 AM by Clark B »
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