The guage (ga) of a shotgun is based on the weight in pounds (lb) of a round ball
of pure lead that will exactly fit down the muzzle of your gun. So, a 1/12 lb ball would, in theory,
fit in a 12ga etc.
Enter the caliber of your Smoothbore in inches or mms.
• It should be noted that such a ball was intended as a calibration tool. A ball better suited for
shooting would be: 'caliber minus (patch thickness x 2)' unless you want to shoot with no patch.
Modern conventional charts differ somewhat from the calculated results:
Gauge (Bore)
Diameter
Weight of pure lead ball
(mm)
(in)
grams
ounces
grains
AA*
101.60
4.000
6225.52
219.6
96080
A½*
76.20
3.000
2626.39
92.64
40530
0.25*
67.34
2.651
1814.36
64
28000
0.5*
53.45
2.103
907.18
32
14000
A*
50.80
2.000
778.19
27.45
12010
0.75*
46.70
1.838
604.80
21.336
9328
1*
42.42
1.669
453.59
16
7000
B½*
38.10
1.500
328.3
11.58
5066
1.5*
37.05
1.459
302.39
10.667
4667
2*
33.67
1.326
226.80
8
3500
3*
29.41
1.158
151.20
5.333
2333
4*
26.72
1.052
113.40
4
1750
B*
25.40
1.000
97.27
3.43
1501
5*
24.80
.976
90.72
3.200
1400
6*
23.35
.919
75.60
2.667
1166
6.278
23.00
.906
72.26
2.549
1114
7*
22.18
.873
64.80
2.286
1000
8
21.21
.835
56.70
2
875
9*
20.39
.803
50.40
1.778
778
10
19.69
.775
45.36
1.6
700
11/C½*
19.05
.750
41.24
1.454
636
12
18.53
.729
37.8
1.333
583
13*
18.04
.710
34.89
1.231
538
14*
17.60
.693
32.4
1.143
500
15*
17.21
.677
30.24
1.067
467
16
16.83
.663
28.35
1.000
438
17*
16.50
.650
26.68
0.941
412
18*
16.19
.637
25.20
0.889
389
20
15.63
.615
22.68
0.800
350
22*
15.13
.596
20.62
0.728
319
24*
14.70
.579
18.90
0.667
292
26*
14.31
.564
17.44
0.615
269
28
13.97
.550
16.20
0.571
250
32*
13.36
.526
14.17
0.5
219
36
12.85
.506
12.59
0.444
194
C*
12.70
.500
12.16
0.429
188
40
12.40
.488
11.34
0.4
175
67.62
10.41
.410
6.71
0.237
104
* These gauges are found in punt guns and rare weapons only. The 410 bore and 23mm caliber are
exceptions; they are actual bore sizes, not gauges. If the .410 and 23mm were measured traditionally,
they would be 67.62 ga and 6.278 ga, respectively.
• Use of this table for estimating bullet weights for historical large-bore rifles is
limited, as this table assumes the use of round ball, rather than conical bullets; for example,
a typical 4 bore rifle from circa 1880 used a 2,000-grain (4.57 oz) bullet, or sometimes
slightly heavier, rather than using a 4 ounce round lead ball. In contrast, a 4-bore express rifle
often used a 1,500-grain (3.43 oz) bullet wrapped in paper to keep lead buildup to a minimum
in the barrel. In either case, assuming a 4-ounce mass for a 4-bore rifle bullet from this table
would be inaccurate, although indicative. (Source: Wikipedia)
The guage (ga) of a shotgun is based on the weight in pounds (lb) of a round ball
of pure lead that will exactly fit down the muzzle of your gun. So, a 1/12 lb ball would, in theory,
fit in a 12ga etc.
