Bore vs. Gauge

[alexm]

I think this is one of the few examples where the British have corrupted words that the Americans use correctly and lately it has started to annoy me slightly. Especially because I have caught myself doing it too. B)

 

In Britain we seem to use gauge/bore interchangeably but on a technicality 'Bore' should refer to a calibre expressed directly by the diameter in inches or mm. For example, .410 bore.

 

'Gauge' should be used to describe a calibre where the diameter is expressed in the number of lead spheres of the calibre's diameter it would take to weigh 1lb. So, in the case of the 12 gauge, 12 lead balls, each with diameter 0.729" would weigh 1lb. 10 gauge, 10 balls, 8 gauge, 8 balls etc.

 

Interestingly a '1 gauge' would therefore be a diameter so large that just one lead ball of that diameter would weigh a pound. This is where we cross over to measuring in lbs. A theoretical "1 gauge" is the equivalent of a 1 lb gun. So the 32 pounder cannons on the bottom deck of HMS Victory are the equivalent of 1/32 gauge guns.

 

So, next time you hear someone say 8 bore, 12 bore etc. then step in and annoy them with your new anal knowledge.

Edited February 4, 2009 by alexm

[libs]

anal knowledge.

 

Was it just me who saw this before ANYTHING else on the page?

[casts_by_fly]

heads would be the head of the loaded cartridge, you know just above the shoulder and neck on the brass?

 

thanks

rick

[Browning]

Along the same lines of things grating on you.....

 

We shoot SHOTGUNS, not bloody 'SHOTTIES' !!!!!

[Axe]

So what 'Guage' would a .410 'bore' actually be?

[CEREALTHRILLER]

Along the same lines of things grating on you.....

 

We shoot SHOTGUNS, not bloody 'SHOTTIES' !!!!!

Deffo - hate that term

[alexm]

So what 'Guage' would a .410 'bore' actually be?

 

Well.... a lead ball of .410" diameter would have a volume of:

 

4/3(pi)r^3 = (4/3) * 3.141 * ((.410/2)*2.54)^3 = 0.591 cm^3

 

The density of lead is 11.34  g/cm−3

 

So a lead sphere of diameter .410" weighs 6.71g or 0.0148 lbs

 

So it would take 1/0.0148 = 67.6 .410 balls to the pound.

 

So it would be about a 68 gauge!

[Dunkield]

So it would be about a 68 gauge!

Is that right

They are only slightly smaller than 28 bore

 

 

The bullet 'head' thing is nonsense as well, as headspace is the gap at the back of the cartridge and the bolt face is it not?

 

 

I don't like deffo either

[Baldrick]

.410 is a 36-bore, in standard gunmaking terms.

Edited February 5, 2009 by Baldrick

[alexm]

Is that right

They are only slightly smaller than 28 bore

 

I know it doesn't sound right, but the 'gauge' isn't linear. Because it's based on weight of a sphere it's proportional to the cube of the diameter of the bore so as the diameter decreases in size the 'gauge' increases to the power three!

[alexm]

.410 is a 36-bore, in standard gunmaking terms.

 

This is a historical thing, it has been referred as a 36 gauge (I have no idea why), but it is in fact a 68 gauge. The maths does not lie!

Edited February 5, 2009 by alexm

[RC45]

so what gauge would 9mm shotgun be?

[alexm]

I worked out the example above on a spreadsheet. Just for fun here is a table of bore (in inches) versus 'Gauge'.

 

As you can see, the 'Gauge' shoots up once the bore starts to get smaller.

 

A .22 is a 438 gauge and a .17 is 949 gauge!

 

Bore(in)	Gauge
1.500	1
1.490	1
1.480	1
1.470	1
1.460	1
1.450	2
1.440	2
1.430	2
1.420	2
1.410	2
1.400	2
1.390	2
1.380	2
1.370	2
1.360	2
1.350	2
1.340	2
1.330	2
1.320	2
1.310	2
1.300	2
1.290	2
1.280	2
1.270	2
1.260	2
1.250	2
1.240	2
1.230	3
1.220	3
1.210	3
1.200	3
1.190	3
1.180	3
1.170	3
1.160	3
1.150	3
1.140	3
1.130	3
1.120	3
1.110	3
1.100	4
1.090	4
1.080	4
1.070	4
1.060	4
1.050	4
1.040	4
1.030	4
1.020	4
1.010	5
1.000	5
0.990	5
0.980	5
0.970	5
0.960	5
0.950	5
0.940	6
0.930	6
0.920	6
0.910	6
0.900	6
0.890	7
0.880	7
0.870	7
0.860	7
0.850	8
0.840	8
0.830	8
0.820	8
0.810	9
0.800	9
0.790	9
0.780	10
0.770	10
0.760	11
0.750	11
0.740	12
0.730	12
0.720	12
0.710	13
0.700	14
0.690	14
0.680	15
0.670	16
0.660	16
0.650	17
0.640	18
0.630	19
0.620	20
0.610	21
0.600	22
0.590	23
0.580	24
0.570	25
0.560	27
0.550	28
0.540	30
0.530	31
0.520	33
0.510	35
0.500	37
0.490	40
0.480	42
0.470	45
0.460	48
0.450	51
0.440	55
0.430	59
0.420	63
0.410	68
0.400	73
0.390	79
0.380	85
0.370	92
0.360	100
0.350	109
0.340	119
0.330	130
0.320	142
0.310	156
0.300	173
0.290	191
0.280	212
0.270	237
0.260	265
0.250	298
0.240	337
0.230	383
0.220	438
0.210	503
0.200	583
0.190	680
0.180	799
0.170	949
0.160	1138
0.150	1381
0.140	1699
0.130	2122
0.120	2698
0.110	3503
0.100	4662

Edited February 5, 2009 by alexm

[alexm]

so what gauge would 9mm shotgun be?

 

105 gauge

[sandy22]

heads would be the head of the loaded cartridge, you know just above the shoulder and neck on the brass?

 

thanks

rick

 

 

So why's the writing at the other end called a headstamp?

[Harnser]

Well ****** me with the bell end of a rag mans trumpet .

 

Harnser .

[palombier]

Since when did definitely become 'deffo'... hate that term.

 

P

Edited February 6, 2009 by palombier

[casts_by_fly]

So why's the writing at the other end called a headstamp?

 

 

because butt stamp just doesn't quite do it. ;o)

 

I guess with a head stamp at one end and the neck and shoulders at the other end, rifle cartridges are the push-me-pull-you of the shooting world.

 

Thanks,

Rick