392 
FOREST AND STREAM. 
[March ii, 19x1. 
r 
ANOTHER WONDERFUL RECORD. 
Mr. J. S. Day, winner of the 1910 Amateur Trap Shooting Average by a percentage never 
equalled, established another and even more remarkable record. In his last 2100 targets, from 
August 8 to 18, 1910 (regulation targets at registered tournaments at Midland, Big Springs, Cisco, 
Gorman and Walnut Springs, Texas), he lost but 34, scoring 2066, making an average never 
equalled or approached by an amateur, 98.38%. This is more than } 4 % higher than the 
average of the winner of the 1910 High Professional honors at 2000 targets. 
Mr. Day bought his loads from dealers where tournaments were held, and they were 
regular PETERS factory goods—not special in any sense. Any one can buy PETERS Shells 
of this same quality, and they don’t have to be used in any special gun to make high scores. 
THE PETERS CARTRIDGE COMPANY. CINCINNATI. OHIO 
New York: 98 Chambers St. T. H. KELLER, Manager New Orleans: 321 Magazine St. P. R. LITZKE, Manager 
San Francisco: 608-612 Howard Street, i. S. FRENCH, Manager 
— .. .... —J 
The Indeterminate “ 12-Bore.” 
Unlike rifle and pistol calibers, the internal diameters 
of shotgun barrels are based on dimensions that have 
been handed down from generation to generation. When 
the fowling-piece was first utilized to fire shot, the barrels 
seem to have been made to sizes determined by the 
diameters of musket balls. No doubt shot and ball 
would both be fired from the same smooth-bore guns. 
In any case, the musket sizes provided a rough and ready 
made standard convenient to work to at a time when ac¬ 
curate measurements of internal diameters, expressed in 
decimals, were not available. Bullets had to be got 
into the tubes, so some kind of relationship between the 
two had, by hook or crook, to be established. A suit¬ 
able basis was found ready to hand. Spherical bullets of 
identical weight, made of the same material and under 
the same conditions, must necessarily be of identical 
dimensions. In practice, the spherical leaden bullets, 
made of metal of indeterminate specific gravity and cast 
.as spheroids, prolate or oblate, or both, would be apt 
to vary widely. Also the internal diameters of the barrel 
would be produced with a very liberal margin for “work¬ 
ing toleration.” When an extra large bullet had to be 
forced down an extra small tube, there would be dif¬ 
ficulties, but for ordinary purposes the method worked 
well enough. To the soldier in warfare the difficulties 
might at times prove intolerable, unless he used his 
musket as a club. In the case of shotguns exact ad¬ 
herence to specific sizes was, in the muzzle-loading days, 
of minor importance. The relationship of weight and 
■diameter in leaden spheres afforded a convenient and 
sufficient basis for the numeration of the bores. Twelve- 
bore is that caliber which takes a leaden bullet weigh¬ 
ing one-twelfth of a pound; 20-bore takes twenty bullets 
to the pound; S-bore, eight, and so on. 
For tubes used with shot, these sizes were as good as 
any other sizes that could have been devised. They af¬ 
forded ample gradations. A pound of lead could be 
•divided into any reasonable number of equal parts. If a 
pure lead bullet could be cast into a perfect sphere of 
exactly the weight required, the caliber would at once 
be determined. With muzzle-loading shot tubes there 
was no great need to insist with great particularity upon 
•accuracy of size. The numbered bores supplied a suit¬ 
able standard to which to work. It was accordingly 
adopted for that purpose, and continues in use. 
In order to keep within bounds, it will be well here to 
confine attention exclusively to the 12-bore size. That 
is the most widely used of all sizes, and it affords an 
•example which in many respects is typical. Going back 
to the first half of the nineteenth century, we find that 
the weight of the ball fired was officially regarded as the 
proper standard for determining caliber. We may rea¬ 
sonably suppose, and we should be right, that gun- 
makers in their workshops had some kind of gauge, in 
the form of plugs, to measure the internal diameters of 
the coiled tubes they used. These plugs would repre¬ 
sent, as accurately as circumstances permitted, the con¬ 
ventional size fixed by the diameter of the ball, although 
the size does not seem to have been expressed arith¬ 
metically. When the Birmingham Proof House was 
established in 1813, a scale of proofs was inserted in the 
act of Parliament passed in that year. Under the head¬ 
ing “Number of Balls to a Pound” were stated sizes 
from 1 to 25, but there was no more definite informa¬ 
tion about the dimensions. Probably the practice of the 
ancient proof house in London was followed, but that is 
only a conjecture. The scale was declared to be “equal 
to the proofs of the Honorable Board of Ordnance.” In 
1815 another proof act was passed. In this the old scale 
was retained. Recognition of the existence of revolvers 
and breechloading guns led in 1855 to the passing of a 
third proof act. In this more elaborate scales were 
provided, and arithmetical equivalents for the various 
gauge were established. They were retained ( in the 
existing act of 1868, to which was appended a “scale for 
proofs of small-arms of every description except ( rifled 
small arms.” There were sixty-three different “num¬ 
bers,” or bores, given, and with each was provided the 
“diameter of bore by calculation.” The “numbers” were 
letters of the alphabet from A (2 inches) down to P, 
and figures from 1 (1.669 inches) down to 50 (.453 inch). 
The 12-bore size is definitely and uncompromisingly stated 
as .729 inch. The next larger size is 11-bore (.751 inch), 
and the next smaller size 13-bore (.710 inch). Accord¬ 
ingly, the 11-bore is .22 inch larger than the 12, and 
the 13-bore .19 inch smaller. [This is an error. It should 
read .022 and .019.—Editor.] Under the act, power was 
given from time to time to alter the scales and regula¬ 
tions for proof. This was fortunate, for in the past forty 
years it has been very necessary to make changes. 
Without attempting to recapitulate all the stages, the 
accepted definition of the 12-bore under the proof rules 
of 1896, and the present rules of 1904 may be stated as 
under. These apply to breechloaders, the size .729 being 
retained for muzzle-loaders without any sub-divisions: 
1S96 Rules. . 1904 Rules. 
Nominal 
Sizes of Proof 
Diameter. 
Ctgs. 
Gauges 
Diam. 
.740 
12.... 
... 12 /. 
... .740 
. .729 
12.... 
... 12 ' ... 
... .729 
. .719 
12.... 
... 13 /, ... 
... .719 
12.... 
...13' ... 
... .710 
The nearest definition that could be given off-hand of 
a 12-bore seems to be that it is a gun chambered tor, 
and intended to take, 12-bore cartridges. The tube is 
required to be something under the size of an 11-bore 
(.751) and something over the size of a 14 /,-bore (.701). 
The gauge size is always marked on the barrels in 
proof, but 12 /, 12, 13 /, 13, would all come under this 
elastic definition of “12-bore.” It is understandable that in 
practice gunmakers prefer to have their 12-bore gun9 
matked with the figure 12 in the gauge mark. Users of 
the weapons, if they investigate such things for them¬ 
selves, are apt to think it queer if a 12-bore is marked 
as “/,. The figure u /„ which may indicate a tube .011 
over the conventional 12-bore diameter of .729, 
much more convincing than 13 /,, which indicates .010 
under .729. The variations either way are considered 
allowable, but the size to which a 12-bore breechloader 
is usually expected to conform is that fixed for the 
muzzleloader of corresponding size, namely, .729 inch. 
T1 e sub-divisions of the arithmetical equivalents of 
the 1855 scale are to be explained by considerations of 
expediency. If a muzzleloader intended for a 1L ^ is 
over or under size it can be called an 11 or a 13. No 
harm is done. But if breechloading cartridges had had 
to be produced for each one of the sixty or so sizes 
denoted by letters or numbers, endless confusion would 
have resulted, while no good purpose whatever would 
have been served. Apart altogether from the manu¬ 
facturing expense, sizes of cartridges differing just 
enough to make the ammunition for one gun unusable 
in another would have caused no end of trouble. Again, 
on the gunmaker’s side, there was the consideration that 
between 11 and 12, and between 12 and 13, there was a 
fairly wide margin. Rigid insistence on exactitude to 
three places of decimals was not customary when muzzle- 
loaders were bored. The size would be there or there¬ 
abouts. The division into half sizes gives us 11-bore 
.751 (which has not got a cartridge and would take 10- 
bore ammunition), and then **/, (.740) .11 [.011] smaller, 
with the real 12 .729 .11 [.Oil] smaller again. Below 12 there 
is 13 /, -1 [-010] smaller, and 13 (which still takes the 12- 
bore cartridge) another .1 [.010] reduction. I he margin 
between the old gauge sizes has merely been sub-divided, 
so that the limits can be shown by the gauge marks 
with approximate accuracy. 
To sum up, the 12-bore gun, with a chamber which, 
since the standard sizes were adopted, should be per¬ 
fectly proportioned to take a 12-bore cartridge, may 
nevertheless have a barrel varying in diameter from .<40 
to .710. The designations by numbered bores, as an 
equivalent for calibers, was probably at all times an 
indefinite kind of method. It is equally indefinite now, 
although the gauge marks, if referred to, bring the ap¬ 
proximation within narrower bounds. If an attempt 
were made to substitute definite measurements for arbi¬ 
trary numbers, it is practically certain that it would not 
succeed. Whether any particular benefit would result 
if it did succeed is extremely doubtful. There are, 
nevertheless, drawbacks to this indeterminate system of 
nomenclature. On another occasion an instance or so 
may be referred to.—County Gentleman. 
The Forest and Stream may be obtained from any 
newsdealer on order. Ask your dealer to supply you 
regularly. 
