Shotgun choke question.

[Ashcroft]

A choke tube bore is slightly larger in diameter than the barrel inner diameter, where it contacts the inner shoulder of the choke tube threaded recess.
Bad things happen to choke tubes if a projectile collides with or gets under the thin skirt of the choke tube. This is why you make sure your choke tubes are tightly threaded in.
A choke tube that has the same or slightly less exit diameter as the bore diameter is called cylinder. The origin of the term may go back as far as muzzle loading shotguns, which originally had no choke.

I don't know when the term Cylinder came into use to denote no choke. It was unlikely to have been used on muzzleloaders because all muzzleloaders were the same, the concept of the choked barrel didn't arrive until the late 1860's, early 1870's when breech loaders were taking over and muzzleloaders were fading from use. The early and increasing use of choke led to great confusion for gunsmiths and makers when measuring barrels so the English proof marks were changed in 1875 to indicate choke if present. Using different markings this continued until fairly modern times.
Yes, the rear lip of a choke tube where it contacts the barrel body needs to be slightly larger than the bore diameter to prevent the outer edges of the shot charge from striking it which would disrupt the pattern. This manufacturing tolerance is often about .010" on guns that are made with care and precision, not all guns are.

 

[Ashcroft]

I think that position is rather unreasonable. Describing a choke as "open" versus "tight" is a useful comparative term. Like referring to one sport bike as "fast" and another as "slow", you have to know it is used to speak relatively and imprecisely. If you want to be more specific you have to know the semi-quantified technical terms for degrees of choke (cylinder bore, skeet, improved cylinder, modified, improved modified, full, extra full), but if you are just chatting about shooting strategies with someone it is enough to mention using an open choke up close and a tight choke at longer range.

In fact even the technical choke terms are really just approximations, so that one shooter may think his modified is tighter than he expected, while another complains that his is too open.

BattleRife gets it.

 

[CZ Shooter]

I think that position is rather unreasonable. Describing a choke as "open" versus "tight" is a useful comparative term. Like referring to one sport bike as "fast" and another as "slow", you have to know it is used to speak relatively and imprecisely. If you want to be more specific you have to know the semi-quantified technical terms for degrees of choke (cylinder bore, skeet, improved cylinder, modified, improved modified, full, extra full), but if you are just chatting about shooting strategies with someone it is enough to mention using an open choke up close and a tight choke at longer range.

In fact even the technical choke terms are really just approximations, so that one shooter may think his modified is tighter than he expected, while another complains that his is too open.

I can see how this could be somewhat usefull to a person, who's familiar with the intricacies of the terminology.
However this can create the exact opposite effect with someone who is just starting out and doing their research.

None of this is properly explained in any of the online articles I came across thus far...the term "open choke" gets thrown around quite a bit without properly explaining how it compares to a cylinder bore, as it is for most part assumed that people somehow know these things automatically.
Someone who bought a cylinder bore shotgun for home defence for example, will be left scratching their head as to why they would need to insert this additional "open choke" device into their barrel, when it is already open.

True, some people won't even flinch when coming across some contradictory information , but I'm known to be very analytical about details that don't add up.
For example, if someone uses the term "four wheeled tricycle", I will dig deep to find out why (as per my post here)

Either way, I would like to thank everyone involved in bringing some clarity on this choke confusion topic.

 

[JW85]

The problem comes when we use removeable machined cylinders to act as the "choke". That external cylinder picks up the name "choke" and in most cases that makes sense. But for a cylinder bore it gets funny.

If we were really strict we could instead call the "open choke" or "cylinder bore choke" a "cylinder bore thread protector" or something of the sort.

 

[saskbooknut]

The problem comes when we use removeable machined cylinders to act as the "choke". That external cylinder picks up the name "choke" and in most cases that makes sense. But for a cylinder bore it gets funny.

If we were really strict we could instead call the "open choke" or "cylinder bore choke" a "cylinder bore thread protector" or something of the sort.

This is just being pedantic.
It's a choke tube, just one with no constriction.
Does cabin fever lead to needless argument?

 

[JW85]

This is just being pedantic.
It's a choke tube, just one with no constriction.
Does cabin fever lead to needless argument?

No argument here, I'm not claiming it matters in practice. Just trying to resolve the naming/terminology quirk the OP is referencing.

I still plan to call my "cylinder bore chokes" by that name.

 

[stubblejumper]

Someone who bought a cylinder bore shotgun for home defence for example, will be left scratching their head as to why they would need to insert this additional "open choke" device into their barrel, when it is already open.

Most people who purchase tactical/defender style shotguns , will never use them other than to shoot zombie targets , so choke really doesn't matter to them anyways. The people that choose shotguns to shoot clays, or for wingshooting, make the effort to learn about chokes, so it makes sense to them.

 

[Falconflyer]

Yes the fact that the barrel widens up at the end was unknown to me before making this thread.
This brings me to a question about my 20 year old 870 Rem Express with 20in (I think) barrel.

I can't see any threads inside the smooth bore barrel and it seems to be the same diameter in and out.
I'm pretty sure it is a cylinder bore and I bought it brand new...it did not come with any chokes and I didn't think to ask.
Later on I bought a Norinco 870 clone called the Hp9 (I think)..same deal...cylinder bore, no chokes.

Does this mean that the two 870's in my posession are not meant to accept any chokes, or em I missing something?

I don't think your missing anything at all. It sounds like your 870 is not threaded for removable choke tubes and the muzzle has the same ID as the bore so it's a cylinder bore choke or "open".

Perhalps if you think of chokes in degree's of constriction it may help. Instead of using the nomenclature FULL, MOD, IC, etc, some folks prefer to use degree's of constriction which I think is a more acurate way of talking about choke. Each degree of constriction is one thousand of an inch and the base line is your specific shotugn bore diamter. For instance if your bore is .733 inches then a cylinder choke should be 0 inches of constriction. A full choke with the same bore diamter should be 35 degrees of constriction (.035 inches) tighter than the bore. A MOD choke would be 20 degrees (.020 inches) and an IC would be 10 degree's (.010 inches) etc. Like I said, it's an acurate way of designating choke however the downside is that most folks won't know what your talking about!

 

[Butcherbill]

Most people who purchase tactical/defender style shotguns , will never use them other than to shoot zombie targets , so choke really doesn't matter to them anyways. The people that choose shotguns to shoot clays, or for wingshooting, make the effort to learn about chokes, so it makes sense to them.

Lots of us use short barrel shotguns to hunt small game with, to those of us that do chokes matter. For me a shotgun without a fixed choke or thread in chokes isn’t all that useful to me regardless of barrel length.

 

[BattleRife]

... but I'm known to be very analytical about details that don't add up.
For example, if someone uses the term "four wheeled tricycle", I will dig deep to find out why (as per my post here).

I think the best advice I can give you here is you need to learn to lighten up. Guns and shooting is not a good endeavour for those who insist on adhering to rigourous standards, because of the vast range of commitment demonstrated by the individuals involved.

Yes, there are researchers and engineers who choose their words carefully, but for every one of those there are ten retired soldiers who are still repeating the jargon and fairy tales told them by their drill instructors, and 20 farmers who just need to put some meat in the freezer and keep the damned badgers out of their chicken coop. Authors of gun books and magazines articles have never made much effort to double check the "facts" they put into their works, and none at all to keep terminology consistent. In this field you can expect to hear people call ammunition cartridges "bullets", refer to box magazines as "clips", insist that nothing with a bore smaller than 2.5 inches may be called a "gun", and reminisce about the time that makers of childrens toys manufactured assault rifles for the US military. If a little thing like using an imprecise term like "open" to describe any choke less than modified raises your blood pressure, then the sheer variety of old wives tales, nonsensical anecdotes and misapplied vernacular you are sure to encounter in the future is going to make your head explode.

 

[Ashcroft]

The British have traditionally used the terms 'Cylinder', '1/4', '1/2', '3/4' and Full to describe degrees of choke. We use the Cylinder and Full terms and rename the others. I think their system ( they also occasionally use 5/8, 7/8 ) and other fractions but normally not because they understand that the name does not necessarily coincide with the patterns thrown, there are many other factors controlling patterns and some of them have as much or more effect than constriction.
Many, maybe most people that I know who shoot guns with removeable chokes screw in the ones that they think will be most suitable for them and never change them. Some experiment a bit with the different tubes before settling on what they are going to use. Almost nobody does extensive pattern testing on paper to see what their particular gun is doing with any specified load and without this testing the best you have is an educated guess. Much different than a rifle shooter, he will spend hours at the loading bench, days at the range trying to shrink that group down to squeeze the last bit of accuracy out of his rifle. Shotgun shooters normally don't get that involved. Why? It's very time consuming and tedious counting all those little holes and doing the math, no fun at all. And in the end the shotgun is an imprecise tool, it produces averages not absolute results.

 

[Wade Kirk]

People are overthinking this. Battlerife was on point. An “open choke” is a relative term. Choke is a spectrum with open at one end and tight at the other. Maybe it should be loose and tight, but it isn’t. Move on. Probably 90% of shooters would be better off to loc-tite one or two light mods in and forget the whole issue.

If someone has a problem with the terminology of “cylinder choke tube” their head would probably explode if they picked up a choke tube and it was labeled “Negative choke.” They are out there.

 

[Pinfire]

https://www.buckmasters.com/Magazines/GunHunter/Articles/ID/2369/Troubles-with-Choke-Tubes

You can do a lot of overthinking about chokes, as previously mentioned. They aren’t magic, they don’t fix a missed swing. Plastic shot cups reduce the effectiveness and need for choke. A hit is a hit, and a miss is a miss. And that miss was probably not caused by choke choice.

 

[barrett50cal]

I also agree with Battlerife. There’s a precedent set by the internal combustion engine which used to use a choke valve to control the air-fuel mixture — at least until fuel injection replaced the carburetor.

An open choke on such an engine would increase airflow, and closing it would restrict airflow — similar to a shotgun.

I’ve always considered the notches on choke tubes as representing the “openness” — so one notch is a tight full choke (turkey chokes are even tighter than this), 2 notches is Improved Modified, 3 notches = Modified, 4 = Improved Cylinder, 5 = Cylinder Bore. A skeet choke would be very open — somewhere between IC and CYL.

As has been mentioned, these degrees of openness/ constriction are more qualitative than quantitative.

One important fact that was mentioned but glossed over: if cylinder bore is desired in a shotgun threaded for chokes, then rather than simply removing any choke tube, you should insert the CYL (fully open) choke tube to protect the threads.

 

[bc308]

This has been a great short course over four pages.

MODS PLEASE MAKE THIS A STICKY, so we can refer newbs and analytics quickly.

 

[CZ Shooter]

I think the best advice I can give you here is you need to learn to lighten up. Guns and shooting is not a good endeavour for those who insist on adhering to rigourous standards, because of the vast range of commitment demonstrated by the individuals involved.

Yes, there are researchers and engineers who choose their words carefully, but for every one of those there are ten retired soldiers who are still repeating the jargon and fairy tales told them by their drill instructors, and 20 farmers who just need to put some meat in the freezer and keep the damned badgers out of their chicken coop. Authors of gun books and magazines articles have never made much effort to double check the "facts" they put into their works, and none at all to keep terminology consistent. In this field you can expect to hear people call ammunition cartridges "bullets", refer to box magazines as "clips", insist that nothing with a bore smaller than 2.5 inches may be called a "gun", and reminisce about the time that makers of childrens toys manufactured assault rifles for the US military. If a little thing like using an imprecise term like "open" to describe any choke less than modified raises your blood pressure, then the sheer variety of old wives tales, nonsensical anecdotes and misapplied vernacular you are sure to encounter in the future is going to make your head explode.

For me it is not really a question of "lightening up"...I'm simply trying to have a deeper understanding of an instrument, that has the potential to create unforseen issues if bad assumptions are being made.

Yes things can be called by the wrong names...as long as everyone is on the same page and understands what the other person meant.

When someone says "clip", instead of a magazine or "bullet" instead of a cartridge, unless the conversation is very specific, it is easy to figure out what he/she really meant.

When someone uses contradictory terminology such as "open choke"..not so much

 

[CZ Shooter]

This has been a great short course over four pages.

MODS PLEASE MAKE THIS A STICKY, so we can refer newbs and analytics quickly.

That is an excellent idea!
I doubt I was the only one trying to figure this out.

 

[BattleRife]

There is no contradiction in the phrase "open choke". It indicates the gun has a choke, in some amount that is not tight. This stands it apart from a gun that has no choke (cylinder bore), or one that has a choke that is relatively tight. The 3 states of no choke / open choke / tight choke correspond nicely to 3 major applications of the shotgun: slugs/buckshot/self defense stuff; close-range wingshooting; long range pass shooting. It is all rooted in pragmatism.

 

[stubblejumper]

For me it is not really a question of "lightening up"...I'm simply trying to have a deeper understanding of an instrument, that has the potential to create unforseen issues if bad assumptions are being made.

Yes things can be called by the wrong names...as long as everyone is on the same page and understands what the other person meant.

When someone says "clip", instead of a magazine or "bullet" instead of a cartridge, unless the conversation is very specific, it is easy to figure out what he/she really meant.

When someone uses contradictory terminology such as "open choke"..not so much

Open choke is far less confusing than using "bullet" when you mean " cartridge" , you can't fire a bullet, without a propellant, but you can use a shotgun, even with a choke that isn't ideal. And "open choke" isn't contradictory, the word "choke" is a noun when used in reference to a shotgun, while the word "open" is just a rough description of the choke.

 

[barrett50cal]

When someone uses contradictory terminology such as "open choke"..not so much

“Open choke” only *seems* contradictory as a superficial consequence of language — like the terms “jumbo shrimp”, “virtual reality”, or “random order”......



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