Front Aperture Selection – Millimeters – DRAFT – Subject to revision.
© 2002, 2010, 2013 – JP O’Connor – jpoc@acm.org – July 2013
***To download a .pdf version of this file click here.
These are minimum starting sizes for the front aperture. Using a size that is 0.1 to 0.5 larger (or more) is perfectly fine, based on athlete preference. Aperture size is in millimeters. Using a size that is only 0.1 too small is fraught with peril. Doing so usually causes insidious problems in shot delivery.
| Eye
Dist. In. |
ISSR
Air 10m |
ISSF
SB 50m |
USAS SB 50ft |
USNRA SB A-36 50ft |
USNRA SB A-17 50ft |
USNRA SB A-7 50ft |
| 28 | 3.5 | 2.9 | 2.8 | 2.7 | 3.0 | 3.1 |
| 29 | 3.6 | 3.0 | 2.9 | 2.8 | 3.1 | 3.2 |
| 30 | 3.7 | 3.1 | 3.0 | 2.9 | 3.2 | 3.3 |
| 31 | 3.8 | 3.2 | 3.1 | 3.0 | 3.3 | 3.4 |
| 32 | 39.9 | 3.3 | 3.2 | 3.1 | 3.4 | 3.5 |
| 33 | 4.0 | 3.4 | 3.3 | 3.2 | 3.5 | 3.6/3.7 |
| 34 | 4.1/4.2 | 3.5 | 3.4 | 3.3 | 3.6/3.7 | 3.7/3.8 |
| 35 | 4.3 | 3.6 | 3.5 | 3.4 | 3.7/3.8 | 3.9 |
| 36 | 4.4 | 3.7 | 3.6 | 3.5 | 3.9 | 4.0 |
| 37 | 4.5 | 3.8 | 3.7 | 3.6 | 4.0 | 4.1 |
| 38 | 4.6/4.7 | 3.9 | 3.8 | 3.7 | 4.1 | 4.2 |
| 39 | 4.7/4.8 | 4.0 | 3.9 | 3.8 | 4.2 | 4.3 |
| 40 | 4.9 | 4.1 | 4.0 | 3.9 | 4.3 | 4.4 |
| 41 | 5.0 | 4.2 | 4.1 | 4.0 | 4.4 | 4.5 |
| 42 | 4.3 | 4.2 | 4.1 | 4.5 | 4.6/4.7 | |
| 43 | 4.4 | 4.3 | 4.2 | 4.6 | 4.7/4.8 | |
| 44 | 4.5 | 4.4 | 4.3 | 4.7 | 4.9 | |
| 45 | 4.6 | 4.5 | 4.4 | 4.8 | 5.0 | |
| 46 | 4.7 | 4.6 | 4.5 | 4.9. | ||
| 47 | 4.8 | 4.7 | 4.6 | 5.0 | ||
| 48 | 4.9 | 4.8 | 4.7 |
Apertures are often selected with only “visual precision” in mind, and are smaller than optimal as a result.
This chart takes into account factors that are far more important; primarily the athlete’s psychological state resulting from the differing visual inputs as the aperture size varies. Apertures that are too small often cause the athlete to hold too long, have “flutter finger” (indecision), poor triggering, and poor follow through.
Athletes who are taken through an experiment protocol that allows them to experience many different sizes (from absurdly small to absurdly large, and everything in between) generally choose an aperture that exactly matches this chart. Interestingly, the chart was constructed based on theoretical research, yet is validated by extensive field work. Results may vary in some cases and additional study is needed for those cases.
This chart is not a magic solution. It is only one critical component in a much broader program that allows an athlete to reliably and repeatedly reach ultimate performance levels. Despite being only one piece of the larger puzzle, this is a critical component. Do not use an aperture that is smaller than this chart!
Please send your comments and observations.
Permission is granted to distribute FREE copies for non-profit educational purposes provided the article is kept unedited in its entirety with all notices, copyright, and other information contained in the document. Any other use requires advance, specific, written permission from the author. The author may be contacted at jpoc@acm.org.
Based in the Atlanta, Ga., area, JP O’Connor (email: jpoc@acm.org and blog: http://jpoconnor.wordpress.com/) is involved in shooting as a competitor, official, and coach. He is a former Assistant National Coach – USA Paralympics Shooting Team and ISSF Judge, serves on the National Coach Development Staff in both rifle & pistol, and is Coach Emeritus of the NCAA rifle and intercollegiate pistol teams at the University of North Georgia. He enjoys working with a number of pistol and rifle athletes and junior club teams from around the country, ranging from beginners to the highly advanced, in training sessions, clinics, and one-on- one private coaching. Previous installments of this series, additional resources, and book suggestions may be found at http://www.pilkguns.com/jparticles/jpcontents.htm and via his blog at http://jpoconnor.wordpress.com/. Email questions and suggestions to jpoc@acm.org.
Links:
“High Performance Olympic Target Shooting” blog, books, and additional resources http://jpoconnor.wordpress.com/
“On The Firing Line” article series and additional resources http://www.pilkguns.com/jparticles/jpcontents.htm