Mr. E. Brown has a cute little single shot action from which he makes both pistols and rifles. eabco.com. In the past he has stocked the Ackley books, paperback. And he has chambered the .30/40 Krag, .30/40 Krag Improved, and the .25/35 Ackley Imp. His passions centers around the Donaldson Wasp case(s). Originally on shortened .30/30 case and later the "ACE" series on the .225 WCF case. Match winners. Many, many matches. With very good barrel life...
It was my great fortune to actually correspond a small bit with Mr. A. I bought the 2 volumes and was most impressed with the .25/35 Ackley Improved Winchester. 3800 fps with a 60 grain bullet. Only 2800 fps with the 120 grain bullets. Then I thought, well, Mr. A was doing this in big, beefy Winchester single shot rifles... so I wrote. He said in a letter, "Nope, get this performace in 94's and 64's (94 with pistol grip) and Marlins right along." This is "efficiency."
I would also add from studying the books, the .25 Krag Improved full length (Mr. A made many variations of the Krag), has the exact same case capacity and data interchanges for the .257 Roberts Ackley Improved. Now the .257 Imp has gone in many directions. .243 Rockchucker probably in the firsts. .244 Remington is just the .257 necked down to 6mm.
.25 Full Length Krag Imp was as good or better than the .25/'06 with powders available in those days until you reached the heaviest of bullets, 120/125 grain and slowest of powders. '06 holds more. Cf. Bliss Titus equaled the .270 WCF with the .300 Savage case necked down (or .250 Savage necked up) to .270 with powders available before WW II and in the Savage 99 rifle.
Best of luck. Books are a great investment even with inet. Happy New Year. Happy Trails.