Wildcat Cartridges

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"The Reloader's Handbook of
Wildcat Cartridge Design"

Wildcatting has been around almost as long as the metallic cartridge case.  Wildcats have an air of mystery about them, no effort is made in these pages to diminish that mystique.  Yet, you will find information here that is simply not available anywhere else.   P.O. Ackley was the last Gunsmith to address the subject of wildcatting in depth.  Over forty years later, Fred Zeglin, Master Rifle Builder and wildcatter has assembled in an easy to read, often humorous manual for anyone who loves guns, reloading, or wildcat cartridges. 

“The Reloader’s Handbook of Wildcat Cartridge Design” is a must have for all shooters regardless of their experience. For the hunter with one gun or collector with many, you will find valuable information on accuracy, designing, building, loading and shooting wildcats.   Calibers start with the tiny .10” ranging to some brawny .50” calibers, there is something for every interest.

Over 150 dimensioned drawings.Publisher Larry Root says, "After 15 years and nearly 30 titles as a publisher, I have found this book a great project with new and useful information rather than a rehashed often incorrect and untested writing that seems so common today. "

"Fred has illustrated his book well, with neat line drawings and photos you probably won’t find anywhere else. It’s a rare technical treatise that draws you in with illustration, or that keeps you with an easy flow of chat that, were it lifted from print, might pop up at any gun counter or handloading bench. Fred Zeglin has done well with this book, giving wildcatters – indeed, all rifle enthusiasts – an overview of a culture often mentioned but little explored on the page."  Wayne van Zwoll

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To read an excerpt from the book, click here.

This Book is currently out of print, however, it is available as a Kindle book from Amazon. Use the link at right to order the Kindle version of Wildcat Cartridges today.


Anyone handloading for a wildcat cartridge will find this a useful reference volume.

Larry S. Sterett, Gun Digest 2007

For anyone interested in having a rifle built for an existing wildcat, re-chambering a currently owned rifle or designing a completely new cartridge, it is highly recommended that they first purchase the book “Wildcat Cartridges” by Fred Zeglin.

Richard Folsland, Reloading, Gun World Magazin, December 2006

One of the problems collectors often encounter when they purchase custom-made sporting rifles is the absence of commercially made ammunition for those arms...  This book offers hope to just those collectors.  

Written by a professional gunsmith and cartridge maker, it examines the history of "wildcat cartridge" development. In addition to discussing vintage designs, such as those developed by P.O. Ackley, Jerry Gebby, and Charles Newton, the book covers more recent work carried out by Estergaard, Gibbs, Z-Hat, and more.

Herbert G. Houze, Man at Arms Magazine, Vol. 28, No. 4, 2006

This is a fantastic book on American wildcats, US loads and much more. 
A must have for wildcatters and gunsmiths.  

Big Bore Journal, No. 18, June 2006

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Table of Contents 

Foreword by Wayne van Zwoll  


1.   What is a Wildcat? and the second most important question, Why bother?

2.   Whatchamacallit…    Lets get our nomenclature straight.

3.   What is an improved Cartridge?   Discussion of “improved cartridges,” 17 Shrew, forming prosess
and how they differ from wildcats.

4.   P. O. Ackley, the undisputed King of Wildcatters.           

5.   Cartridge Case Design and Development.  

6.   Has it been done before?    
He who does not know history is doomed to repeat it!                            

7.  Significant Wildcat Cartridges.   History of Wildcatting, necked down and shortened

8.  Predicting Results,  Knowing what to expect can prevent reworking designs over and over.

9.  Design Principles   Practical discussion of what makes a good design.

   10. Pressure, friend or foe? 

   11. 400 Whelen, Destroying the Headspace Myth  by Michael Petrov

   12. Reamers, Tools for chambers and reloading dies, including how to make your own Reamers.

   Rocky Gibbs13. Chambers… What makes an accurate chamber?   

   14. Accuracy, What is the point in building a wildcat 
           if its not accurate? 

   15. Case Forming Tools and Methods            

   16. Reloading Dies  

   17. Testing, Safe methods of testing wildcats

   18. Examples of Popular Wildcats; Dimensions, History, 
            and Load Data.

   19. Charles Newton, Ballistic Genius   

   20. Jerry Gebby, .22 Varminter; Tracing the history of the 22-250.

  21. Rocky Gibbs, Living on the Edge

   22. Simple Math for the Handloader and Wildcatter  

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Special Thanks to Greg Mushial of www.gmdr.com
Greg provided the much needed software to produce the more than 150 dimensioned drawings in the book.