Choke constriction.

K

kawasakifreak77

New member
Hey guys. On these old dime store shotguns, how do you know how much choke they have when they don't say? I measured the ID of a couple 20ga single barrels dad & I use for quails & on both I'm getting between .595" & .600"

About what does that equate to? Full choke?

Thanks for any help!
 
Don't know. Need to know i.d. of the barrel at least 2" from the muzzle or
"choke".
I.e. If the i.d. below the muzzle was .610 & at the muzzle was .600 then you would have .010 inches of constriction or choke.
Best was to know is to pattern the thing at 40 yards & count pellet hits inside a 30" circle then do the math. Number of hits inside the circle vs total # of pellets in the shot charge. This will give you the percentage of shot inside the circle & you can extrapolate the correct choke of that barrel with that load only.
Or if you like I'll just say they seem to be full choke.:)
 
Ah. I thought the bore per gauge was standard or at least close. Like isn't 20 gauge around a .625" bore which would mean these are around .025" to .030" constriction

That's why I'm thinking they are full chokes but just guessing.

I had a 12 gauge tapped for screw ins & telling the smith I really only hunt upland birds he got me an improved cylinder & said that was only like .005" or .010" constriction. Can't remember exactly.
 
Patterning the gun will be a bigger help. See what it is really doing. The little full choke single shot I had for a while patterned more like mod or IM, for example.
 
According to a choke chart from Colonial Arms, Inc., who sells aftermarket choke tubes, (http://www.colonialarms.com/chokespecs.html) the true bore for a 20 ga. is .617". That would indicate a constriction of .017" to .022" (Between Mod and Improved Mod and between Improved Mod and Full) on your gun.

However, as an example, I've seen several thousandths variation in bore diameters on a number of my 16 ga. Marlin Model 90 O/U's, from top to bottom barrel and from gun to gun. One really needs to measure the actual bore ID and choke ID to get an accurate indication of the amount of constriction.

As has been pointed out, patterning is the only way to know for sure. And, different loads and brands of shells may pattern differently in the same gun.
 
One of the standard reference's is "The Gun" by W.W.Greener. On page 302 there is a listing from the Birmingham Proof House showing bore sizes of different gauges. The 20 gauge is listed at .615 and that is the standard every gun maker uses.

Barrels may be back bored or tapered from the forcing cone but since Colonial Chokes only makes chokes that screw in and not gun barrels they can state what ever they want, but I think most "gun Makers" use .615 as their standard!
 
Awesome! Thanks for all the help guys!

I never hardly gave shotguns a second thought before. Like, shot comes out the end, what more can there be to it? Kinda attitude. But I'm quickly realizing, like anything else, there is a lot to it.
 
If you're looking at older shotguns...be especially careful on "chamber length" as well....

The length of a shotshell...is the "fired length"..../ and some of these older guns...built prior to 1960 or so, might not allow the shooting of modern 2 3/4" shells...

There is a lot to this that comes up in my buddy's used gun shop where he sells all kinds of older shotguns....and too often guys are shopping price ...not specs on the gun ( chamber, choke, etc...)...
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and in this area of the Forum we discuss "Fit" a lot ...because on shotguns your eye is the rear sight ...so "Fit" means, does it hit where you look ...or do you need to change "stock" dimensions ...like length of pull, amount of drop at the comb, amount of drop at the heel....

So its like talking about handguns or rifles...( its not just a shot charge coming out of the end of the barrel )...respectfully ! :D
 
Shooting 2-3/4" shells in shorter (2-1/2" or 2-9/6") chambers may not be a safety issue, but it will definitely increase recoil. The increased recoil, especially with heavier loads, can result in cracked stocks on those older guns. See a discussion at: http://www.lcsmith.org/faq/chambers.html

My dad shot 2-3/4" shells for years in his pre-WWII 16 ga. Springfield-Stevens 215 sxs hammer gun with 2-9/16" chambers without any issues.
 
Despite the study cited ....its my opinion that shooting 3" shells in a gun chambered in 2 3/4" ..../..... or shooting a 2 3/4" shell in a gun chambered in 2 1/2" or 2 9/16"....is not the smartest option.

Maybe the old gun will handle the pressure ....maybe not.

To me - doing so, is a foolish risk to one's own hands and eyes...if you were to find out it couldn't handle the pressure from a partially blocked chamber - then what. Its not a risk I would take !

But my point was .....too many buyers new to the shotgun arena ...know very little about shell length / and falsely assume any 12ga shell will fit in any old 12ga shotgun....( or any 20ga shell will fit in any 20ga shotgun )....etc...
 
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Shooting longer ammo in shorter chambers will increase the pressures. Whether or not that blows the gun up or just accelerates the wear and tear is all dependent on the gun, ammo, and condition of the gun in question. With appropriately made ammo for shorter chambers, there is no reason not to shoot the right stuff
 
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