doublegunshop.com - home Forums Thread Like Summary - Choke percentages at different ranges

I imagine we’re all familiar with these choke percentages from O’Connor’s The Shotgun Book.

30” circle @ 40 yds)
• Full Choke: 70% or higher
• Improved Modified: 65%
• Modified: 55-60%
• Skeet No. 2: 55-60%
• Quarter Choke: 50%
• Improved Cylinder: 45%
• Skeet No. 1: 35-40%
• Cylinder: 35-40

Anyone know if there’s an expanded chart that gives percentages for the chokes at lesser ranges I.e. 35, 30, 25, etc.

If not, taping some of the math minds out there, could those percentages be accurately extrapolated from this 40 yard chart?

See if you can find this: 3/31/2017 Shotgun Sports | Pattern Analysis For Busy Sportsmen by Ron Jones (https://shotgunsportsmagazine.com/archive/mar13/story0313.html) Cites Oberfell and Thompson, The
Mysteries of Shotgun Patterns (Oklahoma State University Press, Stillwater 1957). Here is a table from the book:

Pattern Percentages for All Degrees of Choke for All Distances
Pattern Percentages Distance in Yards 15 20 25 30 35 40 45 50 55 60
Choke Full 100 100 100 96 82 70 58 48 39 32

Modified 100 100 96 83 71 60 49 39 32 26
IC 100 96 83 71 60 50 41 32 26 21
True Cylinder 98 83 71 59 49 40 33 26 21 17

Rough approximation is you lose 10% every 5 yards after 25 yards.

I didn't read Dr. Drew's links, but we are more interested in pattern percentages at different ranges with different chokes, than we are in the pattern diameter. So far, I think we have to go back to shooting 30" patterns and counting holes. Wow, haven't done that for a while. Drew's Field and Stream charts give us all we really need, without counting holes. Thanks, Drew. On a similar subject, I once had a bunch of 1 1/4 ounce lead fours loaded in AA compression formed hulls, ahead of heavy charges of Unique. I shot them at 40 yards out of a heavily choked Sterlingworth and was amazed at how thick the pattern was. I decided to try the same combination at 60 yards, and found that, even though there aren't a whole lot of shot in a load of 1 1/4 ounces of #4, a teal would have had a hard time getting through that pattern. I can't remember the percentages without looking at the pattern sheets, but they were over the top. I was rather amazed. I kept the pattern sheets and still have them thirty years later. Long story short, I sold the Sterly to a friend who shoots ducks, thinking he would put it to good use. He drilled out the chokes and gave the gun to his son to shoot clay targets. I guess we can't save them all.