Shotgun Chokes

Frost

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Years ago when I was a young guy fixed choke barrels were the norm and screw-in chokes were a novelty.
Not so today screw in chokes are everywhere.
There is a wealth of factory and aftermarket flush and extended chokes to choose from.
For years I thought that improved cylinder was the most open shotgun choke, imagine my chagrin when I recently learned that skeet was more open.

Urban wisdom passed imparted to me years ago was that for self defense you should use improved cylinder or cylinder barrels to get the most close range spread.
I guess those guys had never seen a skeet choke.
The internet guys seem to think that rifled slugs are best shot from IC chokes.
Some seem to think that all new slugs have been lawyered to be about 1 size smaller than the barrels they are rated for, i.e. a 12 gauge slug would actually be 13 gauge So they think that improved cylinder stabilizes a slug due its slight constriction

Back in the late 1800's gunsmiths learned that if they reduced the diameter of the barrel at the business end by .020" or .030" that it would hold the shot closer giving shotguns a longer range. Choke designations of Full, Modified, Improved Cylinder and Skeet are determined by the percentage of the shot they put into a 30" circle at 40 yards. These designations standardized into constrictions of the bore by .035" for Full, .020' for Modified .0010" for Improved Cylinder and .005" for skeet. In other words, if you have an internal barrel diameter of .729", an Improved Cylinder choke should have an internal diameter of .719" or ten thousandths of an inch of constriction.

The dimensions choke tubes and shotgun barrels may vary a bit, all factory and generic production chokes and barrels currently available from major manufacturers' include a min and max value. This seems to range plus or minus 2 to 3 thousandths. I read that a guy at Michael Murphy & Sons measured hundreds of choke tubes with a micrometer and has found that about 10% of the factory chokes supplied with shotguns are off more than .002".

Generally we are told that a Foster slug sighted to hit 1 inch above the bull's eye at 50 yards will usually strike 3 inches below the bull's eye at 100. In the real world this varies with the gun and the brand shell.
It takes practice to know what a Foster slug will do from your gun.


In all the owners manuals it tells you not to shoot your shotgun without a choke tube in the barrel.
Yes I suppose you might damage the threads but more likely in my mind is the risk of damaging the barrel due to it's being thinner where the tube goes and needing the support of the tube.
The threads can get polymer from the wad and lead from the shot.
If I never have to chase the threads on a shotgun barrel with a dental pick again it will be to soon.

The box of truth site tells me that shooting shot out of a rifled barrel will give me a donut shaped pattern.

Some say that the best choke for a Foster (rifled) slug is rifled.
They believe that the rifled choke will impart some spin on the slug and help stabilize it.

Remington specifically states
The Slugger Rifled Slug should be used in a smooth bore barrel with an Improved Cylinder Choke Tube.


Speaking of rifled choke tubes most people think they are just for shooting sabot slugs.

Rifled choke tubes can be used with any slug including sabots or Foster slugs and can sometimes improve accuracy with Fosters beyond just a simple smooth bore.

Rifled choke tubes really only work with older Sabots like Winchester BRI sabots, Brenneke K.O. sabots, Hastings Sabots and the Remington BuckHammer.
The BuckHammer uses a projectile shape inside the sabot that is naturally stable in flight using a non-discarding sabot which is also naturally stable.
Remington states "Specifically designed for rifled barrels and rifled choke tubes"
These types of sabots do indeed work well out of a rifled choke tube.
Second Gen sabots such as the Remington Copper Solid Sabot, Winchester Partition Gold Sabot, and Hornady SST Sabot, don't work well with a normal rifled choke.
Seemingly they don't spin up enough to stabilize and you need a fully length rifled slug barrel for them.
 
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