Anyone know the math to do to continue the below chart?
[it's from the http://www.hallowellco.com/bore_size_chart.htm site]

Ga / Bore
________
01 - 1.669"
02 - 1.325"
03 - 1.157"
04 - 1.052"
05 - .976"
06 - .919"
07 - .873"
08 - .835"
09 - .802"
10 - .775"
11 - .751"
12 - .729"
13 - .700"
14 - .693"
15 - .677"
16 - .662"
17 - .650"
18 - .637"
19 - .626"
20 - .615"
21 - .605"
22 - .596"
23 - .587"
24 - .579"
25 - .571"
26 - .563"
27 - .556"
28 - .550"
29 - .543"
30 - .537"
31 - .531"
32 - .526"

Bore Number = 1÷ (R3÷ 9.55) and R = 1/2 caliber expressed in cm

I'll test my understanding of this and see if I catch on.

Easy stuff Jack!

The "3" is an exponent.

I want a 1" "4 gauge" for black powder.
Easy to make smooth bore and easy to make solids from bar stock.

You missed a few in there, according to one of my books that has a British bore size chart in it;
P - 1.250"
O - 1.313"
2 Bore
M - 1.375"
L - 1.438"
K - 1.500"
J - 1.563"
H - 1.625"
F - 1.688"
1 Bore
E - 1.750"
D - 1.183"
C - 1.875"
B - 1.938"
A - 2.000"

These are from the Proof Act of 1868.
Colin

Jack, without getting too arcane:

Take 7000 (number of grains in a pound)

divide by the gauge you want (gives the weight of a lead sphere of that gauge)

divided by 2870 (~grains per cubic inch of lead, gives the volume of the sphere in cubic inches)

divided by PI (3.14159)

times .75

raised to the 1/3 power (in windows, go to the calculator, click 'view', then select 'scientific.' Click on 'y^x' and enter .33333)

times 2

Gives the diameter of that gauge ball.

Bob

Colin,

My interest stops at four bore. I guess once the one inch diam.

is hit, psychologically I arbitrarily decide that the "Enough" point

has been met.

I'm going to try this math now, let's see what happens.

Using Macifej's formula for .499" I got 37.522 gauge or bore. Am I on target?

Now to try O_B's formula.

quote:

Originally posted by Omnivorous_Bob:
Jack, without getting too arcane:

Take 7000 (number of grains in a pound)

divide by the gauge you want (gives the weight of a lead sphere of that gauge)

divided by 2870 (~grains per cubic inch of lead, gives the volume of the sphere in cubic inches)

divided by PI (3.14159)

times .75

raised to the 1/3 power (in windows, go to the calculator, click 'view', then select 'scientific.' Click on 'y^x' and enter .33333)

times 2

Gives the diameter of that gauge ball.

Bob

O_B,

How would you write this out in REVERSE; so that

if you have the diameter in inches and you want to

site it in terms of gauge/bore?

O-Bob has it right, according to the literature. Me? I just look it up in Any Shot You Want.

Jack, the formula for the volume of a sphere is 4/3 x PI x radius cubed. So:

Divide the diameter in inches by 2 to get the radius

Cube it (y^3)

multiply by 1.333333 and by 3.14159 to get the volume in cubic inches

multiple that by 2870 (# of grains per cubic inch of lead) to get the weight of that ball in grains

then divide 7000 (# of grains in a pound) by that number to get the bore or gauge of that ball.

Bob

How about I save you some of the math; Here's the rest of the chart form the 1868 Proof Act:
33 .520
34 .515
35 .510
36 .506
37 .501
38 .497
39 .492
40 .488
41 .484
42 .480
43 .476
44 .473
45 .469
46 .466
47 .463
48 .459
49 .456
50 .453
51 .450
52 .447
53 .444
54 .442
55 .439
56 .436
57 .434
58 .431
59 .429
60 .426
61 .424
62 .422
63 .419
64 .417
65 .415
66 .413
67 .411
68 .409
69 .407
70 .405
71 .403
72 .401
73 .399
74 .398
75 .396
76 .394
77 .392
78 .391
79 .389
80 .387
81 .386
82 .384
83 .383
84 .381
85 .379
86 .378
87 .377
88 .375
89 .374
90 .372
91 .371
92 .370
93 .368
94 .367
95 .366
96 .364
97 .363
98 .362
99 .361
100 .360
101 .358
102 .357
103 .356
104 .355
105 .354
106 .353
107 .352
108 .350
109 .349
110 .348
111 .347
112 .346
113 .345
114 .344
115 .343
116 .342
117 .341
118 .340
119 .339
120 .338
121 .337
122 .3365
123 .336
124 .335
125 .334
126 .333
127 .332
128 .331
129 .330
130 .3295
131 .329
132 .328
133 .327
134 .3265
135 .326
136 .325
137 .324
138 .323
139 .322
140 .3215
141 .321
142 .320
143 .319
144 .3185
145 .318
146 .317
147 .316
148 .3155
149 .315
150 .314

I dont have the patience to test this out but for those who must know:

http://en.wikipedia.org/wiki/G...29#Calculating_gauge

or

http://en.wikipedia.org/wiki/S...ge_Diameter_Formulas

Have a ball!

WOW! All you guys are Great! It seems my math on the .499"

working out to 37.522 ga. is supported by the chart that Colin

generosly posted. I appreciate everybody's posts!