That in some cases the leading pellets are recorded as slower than those behind them, is not, as would at first sight appear, an absolute disproof of accuracy, because it may be that the leading pellets are constantly dropping back, and others are becoming leaders. Obviously the fastest pellets lose speed at the greatest rate, and obviously, also, the leading pellets get least help and give most to their neighbours, by setting up air disturbance, or a breeze, in the direction of the load.
We all know from paper pad and strawboard tests that the penetration of pellets from the same discharge often varies as two to one. Some of these records do not confirm this; but as they can only be accurate on the assumption of that which must be true—the fluctuation of relative positions of the pellets in flight—this adds to their value, because that assumption is also required to explain the greater known variation in penetration than the most indicated in these tables of speed.
The above remarks have been founded on the comparison of the chronographic time of one load at one distance with that of another discharge fired 10 yards farther away; and the mean speed over the 10 yards has been taken as the striking velocity at the midway distance of the 10 yards. This is how Mr. Griffith worked out the striking velocities. And from his figures the length of the shot column can only be got at by making some use of a comparison between shots fired at one range and those fired at another. In other words, the length of shot column approximately found, as described, when divided by the difference of time between first and last pellets, brings out the average velocities of the shot column, at the instant of the leading shot striking the target, too high. That is to say, the previous length of column having been found too much, is taken merely as a basis, to indicate the position in the rear at the length of the column away from the target at which to search for the speed of the lagging pellets, and, with these found, and the speeds of the leading pellets already found, from the table upon page [41], the average speed has been discovered, and actual time between first and last being known, the length of column has been re-found in a way that must be as accurate as any records can be that are based on two different discharges and the chronograph.
Taking the length of the column of shot, it is clear that the difference of time in seconds between the first and last arriving pellets, divided by the length of the column in feet, will give the mean velocity of the shot column at the instant the first pellets struck the target. The amended figures are tabulated on the next page.
It has lately been attempted to show that Mr. Griffith’s measurements are not supported by the results on a target passing at 75 feet a second at right angles with the line of fire. But this speed is not enough to prevent the irregular spread of the shot pellets from misleading. In other words, the faster the movement of the target the less will the elongation of pattern depend upon the accident of pattern, and the more it will depend upon the length of shot column and its speed. Besides this, birds at 75 feet per second are not the difficult sort that people want to learn to kill in a wind.
In the following table it is seen that in one case the column is no longer at 50 yards than at 40 yards, and we may be quite certain shot columns are not so in reality:—
| Yards of range. | Difference of time of arrival of first 5 per cent. and last 3 per cent. of pellets in fractions of a second. | Length of column of shot as corrected by the method previously explained. | Mean velocity over length of column, and striking velocity at a point half the length of column of shot from the end of the range— | Description of gun and load. | |
|---|---|---|---|---|---|
| As found by time from uncorrected length of column of shot. | As found by time from corrected length of column of shot. | ||||
| 10 | ·007 | Choke bore, 42 grains of Schultze and 1⅛ oz. No 6 shot. | |||
| 20 | ·0145 | 12 feet | 1034 | 863 | |
| 30 | ·022 | 16 feet | 1000 | 726 | |
| 40 | ·036 | 22 feet | 777 | 619 | |
| 50 | ·046 | 22 feet | 630 | 489 | |
| 60 | ·054 | ||||
| 10 | ·009 | Choke bore, 49 grains Schultze and the rest same as above. | |||
| 20 | ·018 | 16 feet | 1005 | 884 | |
| 30 | ·027 | 20 feet | 1000 | 768 | |
| 40 | ·0425 | 27 feet | 776 | 647 | |
| 50 | ·05 | 28 feet | 700 | 555 | |
| 60 | ·059 | ||||
| 10 | ·0117 | Cylinder gun and 42 grains of powder and shot the same as above. | |||
| 20 | ·0222 | 18 feet | 990 | 812 | |
| 30 | ·034 | 26 feet | 823 | 769 | |
| 40 | ·049 | 28 feet | 714 | 583 | |
| 50 | ·057 | 27 feet | 526 | 484 | |
| 60 | ·057 | ||||
The only way that this extraordinary result can be explained is this: Mr. Griffith shot at his revolving targets set behind a hole of 4 feet diameter made in a steel plate, and the question arises, Would not any shot pellets that were only travelling at 382 feet a second drop out by the force of gravity, and never pass through the opening at all at the longer ranges? They would take a considerable fraction of a second to reach the 55 yards range, and pellets would drop a foot by the force of gravity in ¼ second, therefore some of them would not pass through the 4 feet opening. On this assumption, instead of the 50 yards columns of shot being of the lengths stated, they must be very much longer, with a continuous dropping of the weaker shot all up the range.
It is often asked how it happens that so few fast driven birds are wounded. They are either killed or not hit as a rule, even when they are high up. Another query is as often heard: “Why are fast birds more difficult than slow ones?” It appears that one answer can be supplied from the tables already given to both questions. It is often said that it is difficult to lead “tall” birds enough, but the farther away game is, the slower the gun has to move in order to race, and beat it, so that this is evidently not the explanation. Taking the corrected length of the various columns of shot at most of the ranges above 30 yards, and comparing the average speeds of the fag end pellets, as given in the table, with the distance they have to go, while the bird has merely to go from 2 to 4 feet to get out of their line, it will be found that game at 60 feet per second cannot get clear of any part of the shot column if it is timed properly, whereas game at 100 feet per second will clear about 40 per cent. of the length of column in some cases, and only incur danger from 60 per cent. as he flies through it. This seems to be ample reason for the greater difficulty of fast game.
Here are a few examples with the 42 grain charge: allowing 6 inches for half the length of the bird, and adding this to the diameter of flying shot column at various ranges, it is found that in order to get clear while the shot column is passing, the bird at 60 feet per second takes .041 of a second. At 100 feet rate of flight he will take .025 of a second, and the shot takes but .022, so that the game does not get an advantage here at 30 yards. But at 40 yards the slow bird takes .05 of a second and gets no advantage; the fast one takes .03 of a second, and here the time of the column is .036, so that, however good the timing, the bird misses some shot. At 50 yards it is still worse for the slow bird, which takes .062 of a second to get through, and better for the fast one, that takes only .037 of a second, when the shot occupies .046 of a second for the whole column to pass.