Post by txbob on Jan 20, 2014 13:08:01 GMT -5
Choke Bore Sizes and Constrictions
The following is a generally agreed upon list of shotgun bore diameters for all gauges and a list of generally accepted choke constrictions (in thousands of an inch) for the various named choke constrictions.
The table above illustrates the constriction left inside a barrel and the choke size "assumed" by the manufacturer. www.parkerguns.org
The following is a generally agreed upon list of shotgun bore diameters for all gauges and a list of generally accepted choke constrictions (in thousands of an inch) for the various named choke constrictions.
| Gauge | 10 | 12 | 16 | 20 | 28 | 410 |
| True Bore Dia. | .775 | .729 | .662 | .615 | .550 | .410 |
| Cylinder Bore | .000 | .000 | .000 | .000 | .000 | .000 |
| Skeet I | .005 | .005 | .004 | .004 | .003 | .002 |
| Improved Cyl. | .010 | .009 | .007 | .006 | .005 | .004 |
| Skeet II | .015 | .012 | .010 | .009 | .007 | .006 |
| Modified | .020 | .019 | .015 | .014 | .012 | .008 |
| Improved Mod. | .025 | .025 | .020 | .019 | .016 | .011 |
| Full Choke | .035 | .035 | .028 | .025 | .022 | .015 |
| Extra Full | .040 | .040 | .035 | .027 | .024 | .021 |
The table above illustrates the constriction left inside a barrel and the choke size "assumed" by the manufacturer. www.parkerguns.org