November 03, 2010
By L.P. Brezny
Full chokes deliver longer shot strings.
By L.P. Brezny
Have you ever wondered exactly what a payload of shot looks like as it contacts soft tissue, or even when exiting the muzzle of a shotgun?
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The use of high-speed photography during a week's worth of test tunnel ballistics has provided new insights about shotshell loads in flight. Using a special camera with lighting that produces photos at 25,000 frames per second, new answers to some age-old questions have surfaced.
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When Part 1 of the Georgia Project concluded, the next step was to employ light bulbs that cost about $8,000 each to slow down the image of a shot cloud, wad and pellet penetration into soft tissue.
Alan Corzine, chief ballistician of Pinnacle Ammunition Company, researched a massive number of shotshell loads using slow-motion photography. He studied shotshell pellets and wads in flight frame by frame to gain a better understand what is happening when a payload of #3 steel or even iron buckshot leaves the muzzle.
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From the time a payload of wad and shot leaves the muzzle until the camera completes it run of photos, only a split second has passed. The payload has only traveled a few feet across the photo field, but about 300 frames of digital imaging have been captured. A careful study of the physical act of the pellets and wad can be completed in detail.
Wad Stop Means No Stop
We viewed a payload of shot moving out of a wad stop style choke such as Pattern Master, Dead Ringer and others. Shooting my own Dead Ringer, which was thought to be a wad stop design with a full 360-degree interior choke ring, the payload becomes trapped while still encased in the plastic wad because the edges of the wad pedals hit the ring and turn inward, developing a crimp of sorts that hold the shot inside of the wad.
As the crimp develops, the pellets are forced back by normal setback forces, and the center of the plastic wad starts to bulge. The encased column of shot will fly as a slug for a few feet beyond the muzzle. The change in release, when compared to a standard choke, causes the payload to stay together farther from the muzzle. The results are tight patterns out to extended ranges, regardless of the shot size, or even in most cases, pellet type.
The Georgia Project, Part 1 Don't miss the first part of our story, click here.
In wad stop chokes that use a series of raised dogs to contact the wad, the reaction is not as complete. As a result, choke tubes like Pattern Master work better with larger pellets.
It takes less crimp action to lock down large shot, whereas small pellets tend to leak through the center of the payload core unless crimped by the use of a ring system.
When a tight full choke is photographed releasing its payload of wad and shot, a very long shot string develops, versus a short shot string produced by a modified choke. We measured shot strings that started to form almost at the muzzle. The strings were a foot long only a few feet from the barrel, and increased to 14 feet at 40 yards.
Modified chokes produced shot strings less than seven feet long. So, you are not shooting as tight a pattern as you think with a full choke, but rather a very, long thin tube of shot.
It is easier to hit with because the string gives a wide margin for the bird to fly through, but as the bird hits the string of skimpy pellets in the column, the amount of shot (payload pellet count density) is greatly reduced from that of a short shot string coming into target contact from a modified choke.
If the new evidence throws a crimp into your thinking about chokes, don't feel bad. I, too, was set back on my heels, and then took up a course of deep reflection on the subject.
The more I study these outstanding photo results, the more I can see what both wad and shot are doing as they head downrange. After 27 years of chasing shot clouds on paper, I can now say I have taken a ride on a payload of shot, at least in a virtual reality sense.
Taking Data to Water
As I changed chokes to shoot fast-moving, tough surf and white-wing scoters that flew low over the water, I made careful photographic and gunning notes of the background pellet contact against the waves as rounds were shot at mostly crossing targets.
My Remington 11-87 mounting the Dead Ringer plastered a single spot on the water with #2s -- even at 40 yards -- so hard it looked like someone had dumped a bucket of shot in one place. Standard Rem choke modified produced a wider pattern by far, but again most of the shot got downrange in a reasonably tight mass. Full choke, however, sent strings of shot boiling across the blue water, producing spikes high into the air in long rows as pellets slammed into the wave tops.
While the details of the ballistic effects regarding the new Pin
nacle non-toxics are best left to another time, it is safe to say that when short shot string patterns hit ducks, birds died faster with less aftershock trauma than birds gunned with less choke, meaning longer shot strings.
If the bird is coming straight on and you get all of the string into the target, full chokes can deliver devastating loads. However, side and slight-angle shots can be a different story. Now I know why I tend to hit several teal crossing at a right angle when shooting a full choke and trying for the lead bird. In effect, the 14-foot-long string of pellets acts like a chain across the face of the whole flock. One-shot doubles can result. I once killed a full limit of six ducks with three shots when leading a big flock of teal. The fact is it was just long shot string going to work -- and a pile of luck. I've never done it again, nor am I likely to.
L.P. Brezny is a ballistics expert from Piedmont, S.D.
