GUN EEPORT NOISE MAXIM. 195 



Then it occurred to the writer that if he could find a place to 

 shoot where there would be no object from which reflection could 

 occur, he ought to secure quiet shooting. It seemed a difficult condi- 

 tion to find until he bethought himself of getting up on a knoll away 

 from trees and other objects and shooting straight up into the air. 

 There would be no objects up in the air to reflect back the bow wave, 

 and, if the theory were correct, such shooting should be almost en- 

 tirely quiet. It was with much interest that a suitable place was 

 searched out. One was finally found, and the first firings were felt to 

 be of great moment. The first shot told the story, for the only noise 

 was the puff of gas from the silencer, which sounded very soft and 

 low. There was absolutely no bullet flight sound heard. The bow 

 wave went on and on and never returned. 



The next thing was to locate the limits of this bullet flight noise. 

 It evidently persisted in certain guns while in others it never oc- 

 curred, while in still others it occasionally occurred. Bullets from 

 various cartridges were fired and it very soon developed that when 

 the bullet velocity reached the velocity of a sound wave, the crack 

 became noticeable. AVhen the bullet velocity fell below the velocity 

 of sound, there was no crack noise. The velocity of sound then ap- 

 peared to be the critical point above which the ordinary bullet could 

 never be fired quietly. It developed that the .22 caliber smokeless 

 cartridges, except in the case of the long, gave quiet shooting, be- 

 cause their velocity was below 1,085 feet per second. The long 

 cartridge appeared in some cases to be above this velocity though 

 not always. There was evidently un-uniformity. The long rifle 

 cartridge was always beautifully quiet, as was of course also the 

 short cartridge. The .22 W. K. F. cartridge, which is a special 

 high power, seemed to be just on the critical line. For example, in 

 a box of 50 cartridges, about half would shoot without bullet flight 

 noise, whereas the other half w^ould make a loud crack. With all the 

 larger caliber regular cartridges bullet flight noise occurred. By 

 using special loads, they all gave quiet shooting. In some cases 

 very heavy bullets were used, and the striking energy maintained in 

 spite of the lower velocity. The reduced velocity of course reduced 

 the distance at which accurate shooting could be accomplished. Two 

 hundred yards always was possible, however, with bullet velocity of 

 1,000 feet per second, which is well inside of the critical point. 



Before the question was considered settled, it was thought neces- 

 sary to make various shaped bullets. Some were made of approxi- 

 mately perfect stream line shape. Others were made with a central 

 hole all the way through the bullet. A copper gas check was used 

 over the base when firing, and this fell off as soon as a bullet left the 

 gun barrel. There never was a single piece of evidence upon which 

 to hang a theory that the noise was in the slightest degree altered. 



