Many tunnel rats reportedly came to dislike the intense muzzle blast of the relatively large .45 caliber round, as the .45's loud report could often leave one temporarily deaf when fired in a confined space. Consequently, some preferred to clear tunnels armed with a .38 Special revolver equipped with a sound suppressor and other non-standard weapons. "A few of the OSS-ordered World War II era suppressed High Standard HD .22 automatics made their way into Tunnel Rat hands. But these weapons were very few in number and wanted by a number of other special units. Personal weapons were used by the rats, ranging from .25 caliber automatics to sawn-off shotguns."