Wikipedia -- P.O. Ackley basic bio. It's a wiki so no guarantee that it's all correct.
Improved Cartridges of P.O. Ackley Download! A pdf collection of articles from GunDigest about and by P.O. himself.
Long Gun Legends--P.O. Ackley Article by Fred Demara
Chambering a Rifle for an Ackley Improved Cartridge. Rifleshooter.com
Handloading: Improved Cartridges? Probably Not. Field & Stream
Measuring Headspace by P.O. Ackley Shooting Times
eBook Edition of Zeglin's 'Wildcat Cartridges' AccurateShooter.com mentions a book that contains some Ackley information.
Deadliest Rifle Calibers on Earth; You Will Never Guess. Thehighroad.org article about Ackley on a Burro hunt.
Rocky's Little Rocket Snippet from Guns Magazine wanders through the wildcatting landscape of yesteryear.
17 Caliber Wildcats -- Redux Richard E. Cundiff article, 6mmBR.com covers some history of the 17 caliber.
The .280 Ackley Improved Keith Wood, American Hunter article.
Falling in Love With the 280 Ackley Improved Corey Graff, GunDigest 2013
280 Ackley Improved Bellm TC's Article specific to Contenders and Encore guns.
257 Roberts Ackley Improved from issue #199 of Handloader Magazine.
Top 5 Wildcat Cartridges by Philip Massaro, American Hunter Magazine
Are Wildcats Worth It? by Ron Spomer, GunHunter Magazine, BuckMasters.com
P.O. Ackley's Big 450 by Terry Wieland August/September 2017 Handloader magazine.
P.O. Ackley's Improved Cartridges by Fred Zeglin Handloader's Digest 2016
Working Man's Magnum by John Barsness for Guns Magazine
The .17 Remington goes to Africa by Leo Grizzaffi for africanxmag.com
North Fork Bullets=Philosophy of Design PDF This article relates to P.O. Ackley's bullet designs.
Promise Delivered by John Barsness The 280 Ackley Improved Lives up to its Reputation.
Ackley Improved Cartridge by John Barsness for Wolfe Publishing.
Mike Bellm's Tribute to Ackley AmmoGuide.com post has some interesting pictures and is direct from Mike Bellm who purchased Ackley's business.
Olympic Arms Closes. One of P.O. Ackley's former partners retires from the gun game.
Gunsmith Writes About P.O. Ackley Description of the book "P.O. Ackley, America's Gunsmith"
Walking in PO Ackley's Footsteps Review of "P.O. Ackley, America's Gunsmith"
Help Identify P.O. Ackley Rifle. Benchrest Central Forum discussion.
Tell me about P.O. Ackley and Interarms Mauser? 24 Hour Campfires Forum discussion.
I think P.O. Ackley was on to something. Shooters Forum discussion.
Article Posted on Precision Shooting Website about Ackley Improved cartridges. Shooters Forum discussion.
Mauser 98/Ackley what do I have? Long Range Hunting Forum discussion.
P.O. Ackley Krag The Fireing Line Forum discussion.
Which Ackley Improved Improves the Most? Graybeard Outdoors Forum discussion.
Ever Heard of P.O. Ackley? XDtalk.com Forum discussion.
Ackley Improved Cartridges.....Are They Worth Doing? TesasPredatorPosse Forum discussion.
P.O. Ackley on the 223 Old discussion on Leverguns.com, very entertaining. Proves the need for historical perspective.
P.O. Ackley Gun Values
Rock Island Arsenal closed auction rifle