THE killing pattern of a shotgun depends not only upon choke but upon gauge. For example, if we take a 12, a 16, a 20, and a 28-gauge, all of them full choked (seventy per cent), and load each with its standard charge of number 8 shot, they will pattern as follows:
12-gauge uses oz.=460 pellets, and patterns 70%=322. 16-gauge uses 1 oz.=409 pellets, and patterns 70%=286. 20-gauge uses 7/8 oz.=358 pellets, and patterns 70%=251. 28-gauge uses 3/4 oz.=307 pellets, and patterns 70%=215.
Each gun throws seventy per cent of its charge into a thirty-inch circle, at forty yards, but the 12-gauge plants nine shot where the 16-gauge places eight, the 20-gauge seven, and the 28-gauge six. The bigger the bore, the more pellets it will handle, of a given size, and the denser will be its pattern, if chokes are the same.
On the other hand, if we load all four guns with the same number of pellets, but still give each gauge its standard weight of lead, then, the bigger the bore, the larger pellets it will handle, and the greater will be its effective range.
We can simplify the discussion of gauges by means of a table that one's eye can take in at a glance. I give, below, average forty-yard patterns of guns of all gauges from eight to twenty-eight, and various chokes, with standard loads of all sizes of shot from BBs to 9s, omitting such figures as are of no practical use. Chilled shot are employed in all cases, except Bs and BBs. (For number of pellets to the ounce, see previous chapter.) The charges here tabulated are:
2 ounces. Heavy 8-gauge. 1 1/2 ounces. Heavy 10-gauge. 1 1/4 ounces. Heavy 12-gauge. 1 1/8 ounces. Medium 12-gauge. Heavy 16-gauge. 1 ounce. Light 12-gauge. Medium 16-gauge. Heavy 20-gauge.
7/8 ounce. Light 16-gauge. Medium 20-gauge. 3/4 ounce. Light 20-gauge. Medium 28-gauge.
30-inch circle, 40 yards. full choke guns=70%.
1 1/4 oz.
1 1/8 oz.
1 1/4 OZ.
1 1/8 oz.
Referring back, now, to the preceding chapter, where killing patterns for various birds are tabulated, the reader can see for himself what gauges and chokes and sizes of shot are effective at forty yards, with customary charges as shown above. Good estimates of performances at other ranges, from twenty to fifty yards, may be made by comparing the work of 12-gauges (see Chapter VII), at forty yards, with those of other gauges shown here, and making proportional allowances, according to charge of shot.
We see at once that size of shot should be regulated to gauge of gun, as well as to size of game. With standard charges, neither a 20-gauge nor a 16-gauge will pattern close enough for ducks, (at forty yards) with any shot larger than number 6; whereas a 12-gauge (full choke, of course) will handle 5s effectively; a 10-gauge, 4s; an 8-gauge, 3s. Similarly, a 20-gauge will make a forty yard goose pattern with 3s; a 16-gauge with 2s; a 12-gauge with Is; a 10-gauge with Bs; an 8-gauge with BBBs. Consequently, if other things are in normal proportion, the bigger the bore, the farther it will kill.
Of course, a small bore can be so built and so loaded as to handle a charge that is " standard" for a bigger gauge; but would we gain or lose by it?
The narrower the bore, the longer the column of shot will be, with a given charge. This means increased friction in the small bore, greater tamping of the powder and consequently quicker burning, greater breech pressure, and a more violent recoil. Moreover, small bores generally are loaded with finer shot than large bores, when used for the same purpose; and the finer the shot, the harder the gun will kick. All experts, I believe, agree that small bores require more gun weight in proportion to shot weight than large bores do. For example, a 12-gauge using two and three-fourths drams of powder and an ounce of shot need not weigh over six and one-fourth pounds, but a 16-gauge charged with similar load should be half a pound heavier; and a 20-gauge, another half pound. Since the prime merit of a small bore is its lightness of gun and of ammunition, it must be apparent that overcharging such a weapon is poor policy.
Hitherto we have been speaking only of shot loads, irrespective of powder. Would anything be gained by using light loads of shot and heavy charges of powder?
We hear a good deal, nowadays, about smallbore " express " shotguns—a term borrowed from the riflemen's parlance of thirty years ago. Anyone can see that if the velocity of shot can be raised, say, two hundred feet a second, without spoiling the pattern, then their effective range will be greater, and a gunner need not allow so closely for " lead " of his bird, nor for drop of shot at long range.
Of course, it is easy to increase the velocity by using more powder, but the trouble is here, that with present systems of gun boring and present methods of cartridge making, any considerable increase above standard charge of powder is likely to batter the shot, lead the gun, and ruin the pattern. We cannot have successful high-velocity shotguns until makers of guns and of ammunition consent to spend a good deal of time and money on something new—and this, naturally, they are loath to do.
Tentative experiments have been made, with encouraging results. It is claimed that a seven and one-half pound 12-gauge has been built in England that brings down overhead ducks from an altitude of fifty to sixty yards. Quite recently, Mr. Charles Askins, the gun expert, has secured an American eight pound 16-gauge in which he uses three and one-fourth drams of Schultz and an ounce of shot, " probably the highest-velocity load eVer regularly shot from an American shotgun." The astonishing thing about this gun and charge is that they make an even pattern of eighty per cent. It will be interesting to learn whether this sturdy weapon behaves well at the fiftieth or hundredth round.