Page:Tactics (Balck 1915).djvu/293

 of the cone of dispersion of the machine gun requires that the appropriate elevation be used if the fire is to be effective against well concealed prone skirmishers. This can be accomplished only in part by employing range finders. Since the probable error of these instruments is ±5% of the range, this determination is so inaccurate for machine gun fire that nothing remains but to increase the dispersion artificially. When it is impossible to observe the strike of the bullets, the dispersion may be artificially increased by employing combined sights, two in a single platoon and three in a machine gun battery (company), and above all by sweeping. The employment of combined sights would appear to be too rigid a method; sweeping fire is at any rate better.

From general ballistic data, Lieutenant-General computes that the following results would be obtained by a machine gun and a detachment of skirmishers when firing with the appropriate elevation at a broad target 1 m. high:—

Machine gun  Detachment of skirmishers At 500 m.   32.4       16.8% hits " 1000 "    15.3        8.1%  " "  1500 "    10.2        5.1%  " "  2000 "     6.4        3.2%  "

This nearly double superiority is reversed, however, when the appropriate elevation is not used:

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==========================================================      |Firing on a target 1 m. high, the following percentages of hits | may be expected when the error in estimating the range is— |      |     50 m.     |     100 m.    |     150 m.    |     200 m. Range.+-+-+-+-+-+-+-+ |Machine| Skir- |Machine| Skir- |Machine| Skir- |Machine| Skir- m. | guns. |mishers. guns. |mishers. guns. |mishers. guns. |mishers. -+-+-+-+-+-+-+-+ 500  |  27.5 |  16.0 |  19.0 |  13.8 |   7.0 |  11.7 |   1.3 |   7.3 1000  |   9.2 |   6.8 |   2.0 |   4.8 |   0.2 |   2.7 |   —  |  1.0 1500  |   3.6 |   3.9 |   0.2 |   1.8 |    — |   0.5 |   —  |  0.1 2000  |   1.7 |   2.2 |    — |   0.8 |    — |   0.2 |   —  |   — -+-+-+-+-+-+-+-+