View Full Version : what are choke tubes

.40 G-27
March 19, 2002, 04:56 AM
I just got a mossberg 500.... and i got two choke tubes.... what are thay for.. and where do thay go... and also can you shoot the gun with out a choke tube..........


Dave McC
March 19, 2002, 05:45 AM
(Deep Breath), OKayyyyy....

Choke is a constriction of the bbl that regulates the spread of the shot.

Choke tubes are a way of getting more than one spread from one bbl and load.They screw into the muzzle end of the bbl.

Shooting a shotgun without a tube in a bbl built for them is a self correcting problem. After one shot, the bbl is not usable, and the shooter possibly the same. Do NOT do this.

Check the Archives for info on tubes, and all other things shotgun.

March 19, 2002, 11:16 AM

Don't the Mossbergs come with 3 choke tubes; full, modified and IC ? If you only have 2 one of them is probably already in the barrel or was lost.

March 19, 2002, 11:45 AM
Haha. You laugh, but I've been shooting for a number of years (Mostly pistol and rifle) and own two scatterguns. I know objectively what a choke does, but have never seen one since neither of my s/g came with one.
Guess what I'm getting at is mebbe we should take pains to make sure people DONT feel slighted if they ask a question that's old hat to the old timers.

Dave R
March 19, 2002, 12:20 PM
Choke tubes are the one real cool advancement in smoothbores in the last 50 years. They allow you to change the choke in your shotgun as needs require. Really improves its versatility.

If your shotgun uses tubes, you MUST have a tube in place, or the shot will damage the threads in the barrel and it will be ruined.

So when/why do you change tubes? You match them to the load you are shooting (shot size) and the target you are shooting at. The "big 4" chokes are (from most open to tightest):

-Cylinder Bore (essentially a straight barrel, not choke)
-Improved Cylinder (very little choke)
-Modified (best all around)
-Full (tightest choke for longest shots)

Other chokes have been added to the list over time: "extra full" for turkey. "Skeet" choke which is between improved and modified (??).

I really only use two: modified and full. Although I've been craving an Improved Cylinder tube lately... Here's how I use them:

-Skeet/trap/clay pigeons: modified choke and size 8 or 7.5 shot. This is where I might switch to IC choke.

-Dove/quail: modified choke and 7.5 shot. Again, maybe IC if the birds are close.

-Hungarians/Chukars: modified or full choke depending on whether the birds are flushing close, or way out there. Size 7.5 shot or 6 shot, again depending on the birds.

-Pheasants: Size 6 shot and modified or full choke, depending on whether the birds are flushing close or way out there.

-Ducks: Full choke (rated for steel) and steel BB shot (at 1500 fps!) if shots are far. Modified choke (steel) and size 1-2 steel shot if the ducks are over decoys or closer.

That's everything I know in a nutshell.

Now, do a search about "patterning" and pattern your shotgun with the different tubes installed. That will give you a clearer picture of what to expect with each tube and each load.

March 19, 2002, 01:04 PM
"We encourage firearm owners to request a free Owner's Manual for their firearms, it’s also a safety-minded and considerate gesture to ensure an Owners Manual is provided should a firearm be transferred to another party. In addition to our postal mailings, we now offer Mossberg Owner Manuals via E-Mail." -- Mossberg Web Site

.40 G-27, Based on your choke tube question I'm guessing you don't have an owner's manual for your 500. Get one and read it before you shoot the gun. You can contact Mossberg here:


To remove and install the choke tubes you need a special tool, or key. Sometimes called a "choke tube wrench." Mossberg's is pretty simple and shouldn't cost more than 2-3 bucks. -- Kernel

March 21, 2002, 07:12 AM
OK then, here is a newbie question: What are slug barrels? Are these barrels that do not accept choke tubes? Are these barrels used for shooting ammo like sabot and 000s?

More than one question huh.. Wait until I put my aluminum underware on... OK, flame on :rolleyes:

Thanks guys :)

March 21, 2002, 10:13 AM
Slug barrels are designed to shoot rifled slugs. They make your shotgun act more like a rifle, firing a single projectile. These barrels are usually characterized by some sort of iron sights, and may be rifled. They will be cylinder bore only as a general rule.

March 21, 2002, 10:45 AM
Choke constrictions for 12 GA shotguns

Cylinder no constriction
Skeet or Skeet 1 .005
IC .010
Lt Modified or Skeet 2 .015
Modified .020
Improved Modified .025
Lt Full .030
Full .035
Ex Full .040

Above info comes from Briley's literature.

Some barrels have interchangeable choke tubes that screw into the barel at the muzzle. It is not a good practice to shoot without a choke tube screwed in.

Older Barrels had a "Fixed" choke meaning they came from the factory with the choke constriction formed into the barrel near the muzzle. Obviously they cannot be changed without machining.

Slug guns come in two types, one with "Rifling" to impart spin to the slug for accuracy and another type that is smoothebore with an open fixed choke that can also be used for buck and shot. Some smoothebore slug barrels may have choke (IE Remingtons which have usually IC choke). Usually "Slug" barrels have rifle type sights or mounting rails for scopes.

MY $.02

:cool: :cool: :) :) :D :D :rolleyes:

March 21, 2002, 10:30 PM
Does barrel length effect the pattern at a given range, using the same choke type? Say a 20" vs a 28" ?

Dave R
March 21, 2002, 11:24 PM
Very little, if at all. The choke is what drive spread.

Barrel length can affect velocity. Going from 18" to 24", for example, should get you more velocity. A longer barrel probably won't get you much more velocity. So why do people use longer barrels? So they get a longer sighting radius, which can help precision, and they get a swing with more "dampening." Right, guys?

Dave McC
March 22, 2002, 05:01 AM
Right, Dave. I was digging around yesterday, and noted that one bbl that was cut from 28 to 20" dropped velocity about 42 FPS, IIRC. There's that much variation between shells in a box of field loads.

Choke is the biggest factor in spread,then there's things like shot hardness, velocity,bore diameter, the phases of the moon, etc. Shotgun ballistics are arcane as heck.

Longer bbls tend to be more weight forward, or "Muzzle Heavy". This adds a bit of inertia, helping the swing.


March 23, 2002, 08:01 AM
That helps a lot. Your help is appreciated :cool: