Choke Measuring

sigarms226

sigarms226

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Hello, I've got an older Citori, Auto 5 20 and Stevens pumps with fixed chokes. I'm curious how one can measure what the choke constrictions are in these fine firearms. I must admit I've no experience with fixed chokes as all my other shotguns have removable chokes. Much Thanks.

Sig.
 
12gauge bore dia-.729 ...amt of constriction [Full .035][imp mod .025] [mod .019]+[IC .009] 20 gauge bore dia -.617......amt of constriction [Full .025][imp-mod .019][mod .014][IC .006]..........Harold......a dime won't fit in a full 12 gauge muzzle but will in a Mod
 
The dime works well as it only partially enters a full choke,with a mod. the dime goes almost halfway, imp. cyl. dime enters completely.
 
Choke is the difference between the muzzle diameter and the bore diameter. Measuring the muzzle does you no good unless you already know the bore diameter, something that takes specialized equipment to measure.

Fortunately there is a much better way to assess choke. Find some paper forty inches wide and high. Draw a circle thirty inches in diameter on it. Shoot the paper from a distance of forty yards and count the pellet holes in the circle. If 75% of the total number of pellets in the load fall inside the 30 inch circle then you havre a full choke barrel. 67% = modified choke, 57% = improved cylinder.

The advantage of measuring in this way is you get to know the actual choke performance with the load you will be using, not some theoretical number. Choke performance varies with different loads, sometimes quite a lot.


Sharptail
 
Except some mod chokes will through FC patterns.This can vary gun to gun and shell type to shell type.I find Soviet guns choked very tight and a .410 brush won't exit my Savage 24 .410/.22 but it throws grouse killin patterns out to 30 yards! And I can shoot clays with it as they used to regulate the barrels back in the day............hope that helps......Harold
 
A bore gauge measures the difference between the bore and the choke constriction.

l_843200126_1.jpg
 
Longwalker said:
Yup. I have one of those, it's the only way to go. All else is conjecture and speculation!
Click to expand...

Correct ... the one I have is the 4 gauge (12, 20, 28 & 410) set from Custom Shooting Products (I think they are out of business). They also show lumps and bumps in the barrel. Great tool, when you are buying a shotgun.
 
Mine's called a Skeet's bore gauge, from Brownell's. One gauge can do both 12 & 16 bore guns, the smaller size can do 20 & 28 ga.
brownells.com/.aspx/pid=12736/Product/SHOTGUN_BORE_GAUGE
US $95
 
A dime's all you need for most barrels, we're not measuring Kreighoffs or Stan Baker overbored barrels here, once you use it to get a fix on one particular choke the rest are obvious. The dime is used if you are in a shop and something catches your eye and you wan t o know the choke, or you're out in the field and you meet up with a buddy and start talking guns, and why he is missing birds, and you don't have time to order from Brownells.
 
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