In another post, it was mentioned that a dime will tell you whether your choke is full or not. If the dime goes in the choke it is less than full, if it doesn't the opposite is true. Or at least that's the theory.
So I measured 5 American dimes and the average width is .704 inches -- ranging from .702 to .705. If the standard bore diameter of a 12 gauge shotgun is .729 inches the difference or "constriction" is .25 inches which is between modified and improved modified. The standard full choke constriction is .35 to .40 inches.
But the measurement of the choke at the end of the barrel is only relevant if you know the interior barrel diameter. On a backbored shotgun of say .755, you could drop the dime down a barrel that has an extra full choke.
On the other hand, Italian shotguns are often very tightly bored. My Beretta 682 has barrels that measure .723, therfore at .704 the dime represents a modified choke.
Now for the practical test. I dropped the dime, so to speak, on 3 of my guns. The Krieghoff Model 32 marked IM and F allowed the dime to pass. The Beretta 682 would not allow the dime to go through either the IM or Full tube (remember the tight chambers, the chokes are a little tighter to make up the difference). A live pigeon sxs choked .29" and .43" allowed the dime through the more open barrel but not the tighter tube.
However, barrel constriction is not a true measure of choke, performance is. Full choke is 70 percent of the pellets into a 30 inch circle at 40 yards. But with judicious reloading, I can change choke performance at least one designation in either direction. Lower velocity, harder shot and larger shot all generally contribute to tighter patterns. There are also special wads available that will open up shot patterns for guns that are tightly choked. The aforementioned live pigeon gun would have been an aerial meat grinder on grouse hunts were it not for spreader wads.
It doesn't matter what the barrels say or even what the constriction is. What matters is whether your gun meets the standards of choke performance.
This little exercise has taught me two things: The first is that trying to measure chokes with a dime only proves that you have a dime and a shotgun. The second thing is that I didn't have enough to do today.
[This message has been edited by PJR (edited October 23, 2000).]
So I measured 5 American dimes and the average width is .704 inches -- ranging from .702 to .705. If the standard bore diameter of a 12 gauge shotgun is .729 inches the difference or "constriction" is .25 inches which is between modified and improved modified. The standard full choke constriction is .35 to .40 inches.
But the measurement of the choke at the end of the barrel is only relevant if you know the interior barrel diameter. On a backbored shotgun of say .755, you could drop the dime down a barrel that has an extra full choke.
On the other hand, Italian shotguns are often very tightly bored. My Beretta 682 has barrels that measure .723, therfore at .704 the dime represents a modified choke.
Now for the practical test. I dropped the dime, so to speak, on 3 of my guns. The Krieghoff Model 32 marked IM and F allowed the dime to pass. The Beretta 682 would not allow the dime to go through either the IM or Full tube (remember the tight chambers, the chokes are a little tighter to make up the difference). A live pigeon sxs choked .29" and .43" allowed the dime through the more open barrel but not the tighter tube.
However, barrel constriction is not a true measure of choke, performance is. Full choke is 70 percent of the pellets into a 30 inch circle at 40 yards. But with judicious reloading, I can change choke performance at least one designation in either direction. Lower velocity, harder shot and larger shot all generally contribute to tighter patterns. There are also special wads available that will open up shot patterns for guns that are tightly choked. The aforementioned live pigeon gun would have been an aerial meat grinder on grouse hunts were it not for spreader wads.
It doesn't matter what the barrels say or even what the constriction is. What matters is whether your gun meets the standards of choke performance.
This little exercise has taught me two things: The first is that trying to measure chokes with a dime only proves that you have a dime and a shotgun. The second thing is that I didn't have enough to do today.
[This message has been edited by PJR (edited October 23, 2000).]