[104-10216-10234.pdf — page 1]
5. Tests were conducted in the evening to determine the degree   of usefulness of the sight in poor light. In this respect a 22   Caliber Hi-Standard pistol with folding shoulder stock and Bushnell   1.3X Phantom scope was tested in comparison. The scope was   equipped with yellow filters to brighten the sight picture for   low light level use. It was the opinion of both test personnel   that the scope was superior to either the peep sight or open sight   for as long as their was some illumination on the silhouette   targets. Once the light failed the scope was completely useless   although the undersigned could still discern targets with the naked   eye out to 50 yds. All actual shooting was done with the open   sight and some difficulty was experienced in hitting the targets   at ranges of 100 yds. or more even at dusk. The closer targets   could be easily hit up until it became too dark to see them at all.   A large rain cloud moving from behind the firing position gradually   obscured all available light. For the final shooting at 25 yds.   occasional lightning flashes gave only a vague awareness of the   target location. At no time during the night trials was there any   muzzle flash visible from the under loaded ammunition and suzzle   silencer combination. The gas port which was in the off position   during the daylight trials vas turned on at night but no flash was   visible at the breech. A fine white cloud of cream of wheat   powder was visible in front of the muzzle at almost full darkness   but could not be seen more than 30 feet away.6. Listener trials were conducted the following day to deter-   mine how far away an alert listener could discern the mechanical   noise of the mechanism and that of the round being fired. Hr. Ricker   walked away downwind at an angle of 90 degrees to the line of fire   and stopped to listen every 25 paces. The undersigned fired   single rounds, (hand actuating the pechanism) each time Nr. Ricker   stopped. At 335 paces, or roughly 275 yds., Er. Ricker reported.   he could still hear the mechanisa being actuated, the round being   fired, and the bullet striking a concrete pillar 200 yds, down-   range. However, he stared that he might not have noticed the sound   at that range had he not been listening for it specifically.7. One of the major causes for concern at the start of the   tests was that the cream of wheat filler might clog the silencer   and render it ineffective. A total of 200 rounds were fired with   the silencer in place and the noise level did seem to be higher at   the finish of the second day. (Round numbers 180 to 200 were the   ones expended during the previously mentioned listener trials).   Inspection of the silencer at a later date revealed considerable   crean of wheat residue in the screening. Sound level measurements   made in the AMF sound lab showed that while the total noise level   vas no higher, the duration was relatively longer. This would   make the silencer seen louder to near by observers but not increase   the range at which it could be heard. However, from a stand-   point of the ability for a listener to discriminate a silencer   being fired from random noise, the longer duration gives him a   better chance to recognize what he hears.