GUNS AND AMMUNITION. 



2 93 



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-Leapold, of Norristown, Pa., who measured 

 through light screens very many spirals — 

 and later by me. The results showed that 

 the width of the spiral from an accurate 

 charge was very small, but one can pro- 

 duce an exaggerated spiral flight, as is well 

 illustrated in several trajectory tests of ex- 

 press rifles, having high velocity and light 

 bullets. In some cases the spiral was so 

 exaggerated that in shooting through 

 screens at 200 yards the trajectory would 

 be higher at 50 yards than at 100 yards. 

 To return to the explanation of drift: 



Fig. 2. — A shows the 

 bullet just after leaving 

 the barrel, the observer 

 being behind the gun. 

 The resistance of the 

 air will elevate the apex 

 as shown at B. The 

 motion of rotation be- 

 ing to the right the 

 point will begin to move 



V\ CT\ to tne r 'S nt ' C, and the 



* J I !J resistance of the air will 



cause the point to con- 

 tinue moving to the 

 right until it reaches D, 



O-^ at which point the drift 

 (\jS is entirely horizontal 



* \sS$/ and to the right. Up to 



£ this point it is evident 



there have been 2 drifts 

 in operation, an upward 

 or vertical and a horizontal drift ; for as soon 

 as the axis of the shot begins to move to 

 the right the left side of the snot receives 

 the greater resistance from the air and the 

 tendency is to force the projectile bodily 

 upward and to the right. 



When the projectile reaches D the cir- 

 cumstances of the case will change slowly, 

 for the tangent to the trajectory, Gt (Fig. 

 3), does not remain parallel to AH, but is 

 always dipping downward; while the re- 

 sistance of the air in this case causes the 

 axis of the shot to dip downward. Should 

 the tangent, gt, dip more rapidly than the 

 axis, ga, the projectile will tend to return 

 to position C, and the motion of the pro- 

 jectile becomes oscillatory. This is likely 

 to happen when the angle of elevation is 

 great, the velocity low and the trajectory 

 much curved. 



Fig. 



and the projectile will assume positions 

 E . . . H, and afterward the axis, ga, 

 may go on rotating about the tangent, gt, 

 and may make one or more complete revo- 

 lutions, depending on the range. 



A very important fact is that when the 

 point of the projectile is to" the right of the 

 vertical plane passing through the tangent, 

 the tangent, gt, to the trajectory and the 

 axis, ga, of the projectile are both dipping 

 downward; but when the point of shot is 

 to left of vertical plane passing through the 

 tangent, the tangent, gt, is dipping down- 

 ward, but axis, ga, is rising upward. Hence 

 the drift will be in operation a much longer 

 time to the right than to the left. The rea- 

 son of this is evident, for the tangent to 

 the trajectory is always dipping; but the 

 axis of the shot is rising after it passes posi- 

 tion D and is to the left of the vertical plane. 

 The former is due to the action of gravity; 

 the latter to the resistance of the air. 



It is evident there is a drift in every direc- 

 tion. The vertical upward drift exceeds in 

 magnitude the downward, especially since 

 the bullet passes at a high velocity from A 

 to D and is lifted up and made to move as 

 though fired at a higher angle of elevation. 

 The vertical drift is in small proportion to 

 the horizontal drift in ordinary small arms 

 firing, since the angle of elevation is very 

 small. Vertical and horizontal drifts are 

 only components of spiral drift. 



I believe any cause that increases the ver- 

 tical component of drift leads to inaccuracy; 

 such as high angles of elevation and high 

 velocity, above a normal limit. Light hol- 

 low pointed bullets fired at a high velocity 

 produce exaggerated spirals. The widest 

 that ever came under my notice had a width 

 of 10 inches in going 200 yards. In the most 

 accurate rifles the spiral is so slight that 

 it is impossible to measure it in some 

 cases, showing that the vertical component 

 of drift is small compared with the horizon- 

 tal component. 



All the above phenomena Would be re- 

 versed with a left handed twist. 



Fig. 



But at ordinary angles and velocities the 

 axis, ga, dips faster than the tangent, gt, 



A NEW POWDER. 



Cincinnati, O. 

 Editor Recreation: To the devotees of 

 field sports there can be no more interest- 

 ing Beading than such as is offered in Rec- 

 reation's department " Guns and Am- 

 munition." No story of days on the uplands 

 or in the marshes can take the place of a 

 plainly stated review of actual experiments 

 with guns and powders and their results. 

 The former, if well told, help one to pass 

 a pleasant hour — to live again in memory 

 happy days of the past; the latter stimulate 

 an interest in the present, advance new ideas 

 and furnish subjects for active considera- 

 tion. 



