Shotgun Choke Patterns and Information

The amount of choke in a barrel is determined by subtracting the inside diameter of the choked area from the diameter of the bore, both measured with special gauges.  Choke is considered Full if its choke diameter is .035 inches smaller than the bore.

Caution:  Just because your gun delivers Modified (or whatever) performance with one load doesn't necessarily mean it will do the same with other loads. Also keep in mind that just because the barrel of a gun or its screw-in choke was marked "Modified" or "Improved Cylinder" at the factory does not mean it will deliver Modified or Improved Cylinder choke performance with all loads.

Different loads from various manufacturers or even different loads from the same manufacturer can vary  Even though the load you just tested delivered Modified performance, another load might deliver Improved Cylinder performance while the next might perform as if your gun is choked either tighter or looser.  Bottom line is shoot your gun at the paper with different loads and make your own determination of what choke and load is best suited for your shooting circumstances.

 

 
Percentage Of Shot Inside 30" Circle
CHOKE 20 Yds 30 Yds 40 yds
Cylinder (No Choke)
80%
60%
40%
Skeet
92%
72%
50%
Improved Cylinder
100%
77%
55%
Modified
100%
83%
60%
Improved Modified
100%
91%
65%
Full
100%
100%
70%

 
Number Of Pellets Per Ounce
SHOT SIZE LEAD STEEL
8
585
- - -
7 1/2
410
- - -
6
225
316
5
170
243
4
135
191
2
87
125
1
- - -
103
BB
50
72
BBB
- - -
61