Re: Lever Action SBS in progress pics
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762, you do have an interesting knack about you.
Great Lakes Arsenal is long gone...
Approximately 5,000 "Lo-Thro" chokes (duck bill) were produced at China Lake NWAS and Frankford. Three guys, Greenwood, Madurski & Dockery, two probably alive would know best. Some where made them in the 90's.
"the US Air Force Directorate of Security Police in the mid-1960s developed a requirement for a spreader choke that would produce a wide elliptical shot pattern. This horizontal pattern spread was supposed to increase the hit probability from a shotgun on a moving target. Recall if you will that the Sixties were a time when the war in Vietnam was heating up, and civil unrest in the US was too. Lots of people in police and military circles were interested in many aspects of weapons both lethal and non-lethal. Shotguns came in for their fair share of attention, especially given their role at the time as the primary law enforcement long gun.
The Air Force request went to Frankford Arsenal for action, at the time Frankford was working on improvements to the military shotgun in general. Early experiments at producing a spreader choke were less than successful- the chokes split, patterned poorly and in various ways failed to produce the desired results.
The original duckbill choke was simply a sleeve with a long V-notch cut on either side, the apex of the V toward the rear. The top and bottom of the sleeve were compressed toward the centerline at the muzzle, constricting the emerging pattern of shot in the vertical plane and forcing it to spread horizontally. The sleeve was permanently brazed onto the barrel so that it would not be blown off or rotated by firing the gun.
Early examples of duckbill- equipped shotguns were deployed to Vietnam in the hands of Marines and Navy SEALs. It was found that the open V- notches in the muzzle of the duckbill hung up badly on vegetation as the shotgunner tried to move through thick growth, so the duckbill was modified with a ring around its muzzle to exclude vines and branches. It was discovered that the spreader device worked as advertised, but in reality what was needed in a fighting shotgun was a way of producing dense, lethal patterns.
Spreaders in field testing produced patterns five feet high and twelve feet wide at 30 meters with #4 buckshot loads. At 40 meters, patterns were six feet high and sixteen feet wide. At 40 meters an average sized man would only be hit by a couple of pellets. But with a standard cylinder bored barrel shooting approximately a four- foot circular pattern at 40 meters, some 60% of the shot would strike an average man- sized target.
Still, the duckbill choke had its adherents, among SEALS especially. Development on the idea continued for several years. Clifford Ashbrook and Wilson Wing of Kexplore, Inc. in Houston, TX developed the A&W Diverter in the late 1960s using mathematical concepts, and received patent protection (# 3,492,750) in February 1970. It is expected that the controversy over spreaders and diverters will continue. It appears from available data that they will find little employment in actual combat." World's Fighting Shotguns.
Also, see the patterns of the A&W Unit here:
http://www.thehighroad.org/showthread.php?t=418779
The resulting pattern was an elliptical spread, not as broad and narrow as suggested. Remember also, no slugs, ever.
Here is the A&W
or...
http://thefiringline.com/forums/showthread.php?t=82686
Hey, you asked...
