Get more sizzle out of an older rifle by modifying it the P.O. Ackley way.
By Ron Spomer
The big ram had been below us at the edge of the glacier, covered by ground fog. It wasn’t until my tough young guide, Striker Overly, had dragged me gasping into the sunshine well up the mountain flank that we even knew the full-curl Dall’s was still in the neighborhood. The kid had seen it earlier in the summer, but I was the first client willing to endure the 8-mile backpack trip up the glacier to reach its hideout.
“Ewes. Damn.” In his enthusiasm, Striker had poked his head over a rim too fast. A big herd of ewes and lambs had been resting within bow range. Instantly they were up and running. We looked around frantically. Rams? Where are the rams? Big males rarely hang with females and young until mating season, but you never know. “Not here,” I said.
“There he is!” my guide hissed, pointing below and behind us. The fog had cleared to reveal two rams, a youngster hardly worth a second glance and a regal monarch with horns curling up and back and down and back up unlike anything I’d ever seen in the flesh, not even in Denali National Park. This was a Boone and Crockett contender, and it was spooked and running.
“I don’t think it’s seen us or quite figured us out if it has. It’s just reacting to the ewes.” The big group of white animals was milling above us, heads up, alert, looking back down, enough body language for the dumbest ram to understand.
“It’s going up to the cliffs. We’ve got to cut it off! Dump your pack
Both rams had already disappeared into a canyon, running at an angle that would keep them out of sight behind a bulge in the mountain. We ran over rocks and scree to crest it. By the time we did, I was gasping like an overweight schoolteacher at his first marathon. The rams were already above us and across a canyon. “Can you hit it from here?”
“I think so. What do you put it at? Three-hundred twenty-five yards or so?”
“More like 400. No, maybe 350.”
I crabbed forward to a flat-topped boulder that looked encouragingly like a benchrest, and laid my Rifles Inc. Strata Stainless over the top, my elbows on the black rock. I sucked in a few gallons of thin mountain air. The rams wheeled, fidgeted, but stayed. The uphill angle would work in my favor, but not much. “It’s shooting about 4 inches low at 300 yards,” I said. “I’m going to hold just under its backline. Call my shot.” I took a deep breath, let half go, held and pressed the 21/2-pound trigger.
Striker called the shot “perfect.” The ram collapsed and cartwheeled down the canyon, shot through the chest with a 150-grain Barnes X bullet sent flying by a cartridge most hunters have never seen — a .280 Ackley Improved.
Ever since the first metal-lic cartridge was constructed way back in the mid-19th century, shooters have been improving it. Going from rimfire ignition to centerfire ignition accommodated higher pressures. Changing from straight-walled to bottlenecked cartridges added horsepower to smaller bullets without lengthening actions.
Stepping up from black to smokeless powder really increased power. Magnum cartridges punched speed up another few hundred feet per second, and new versions on the magnum theme continue adding incremental gains.
After all that, there wouldn’t seem to be much the average shooter/hunter could do to improve his rifle/cartridge performance short of buying a new outfit, lock, stock and barrel. But there is. And it’s relatively cheap and easy. Just “improve” your current cartridge/chamber by slightly altering its shape/volume.
“Improved” cartridges were popularized by gunsmith, barrelmaker, writer and wildcatter P.O. Ackley in the 1940s through the 1960s to such an extent that his name had become a verb in some circles, as in “I’m thinking of Ackleyizing my .30-06.”
Wildcatting is generally understood as modifying a standard cartridge to create a different one. This can involve one or any of the following:
• Changing the body taper (decreasing the taper increases powder capacity).
• Sharpening the shoulder angle (increases capacity and minimizes cartridge stretching during firing and resizing).
• Moving the shoulder forward and shortening the neck (increases capacity while continuing to function on original magazine/action port).
• Changing the neck diameter to accommodate another caliber, either larger or smaller (necking the .30-06 down to .277 inch gave us the .270 Winchester. Down to .257 gives the .25-06 Remington. Up to .358 yields the .35 Whelen, etc).
• Shortening the body length creates a cartridge that functions in shorter actions at lower velocities (.243 WSM from .300 WSM case).
Technically, an Improved case differs from a wildcat in that the Improved chamber still accepts and safely fires the original factory ammunition, according to P.O. Ackley’s 1962 “Handbook For Shooters & Reloaders, Volume 1.” Thus, you can fire a .25-06 Remington factory load in a rifle rechambered to .25-06 Ackley Improved.
Mr. Ackley tried a variety of shapes with his cartridges, but seemed to settle on a rather standard design in which just enough taper was left in the case to ensure easy extraction, and the slope of the shoulder was set at 40 degrees. Maintaining the base-to-shoulder distance of the original round prevented excessive headspace, which is why standard factory cartridges can be safely fired in an “improved” chamber.
At the shot, the brass case expands to fill the new chamber and thus is ready for handloading, the powder capacity having increased usually 5 to 10 percent. Not a huge gain, but enough to approach typical magnum velocities with considerably less powder and without the need for longer actions or wider bolt faces.
Magazines, loading ramps and lips do not need modification, either. Improved cartridges feed and function as smoothly as the originals, although some shooters have complained that the sharper shoulders won’t feed as smoothly. That has never been my experience.
Not all improved cartridges are worth the trouble. The .30-30 Ackley Improved, for instance, gains about 250 fps more velocity than its parent cartridge, but since both must fire relatively inefficient flat-nosed bullets (from tubular-feed magazines), trajectories are not appreciably extended.
The .280 Ackley Improved, however, proved so efficient and raced so near the heels of the 7mm Rem Mag that Nosler recently legitimized it as a SAAMI factory round. According to the Nosler Reloading Guide No. 6, a .280 Rem will drive a 160-grain bullet to a top speed of 2,929 fps. The .280 Remington Ackley Improved boosts that to 3,045 fps.
The 7mm Rem Mag, in comparison, kicks it to 3,077 fps, but the magnum burns 10 more grains of powder to earn that 32 fps advantage over
Now, if you own a .280 Remington and want 7mm Rem Mag performance, hire a gunsmith to rechamber to a .280 Ackley Improved. You can continue shooting standard .280 Rem ammo (with some loss in velocity) to fireform brass to the new chamber shape. After that, you’ll handload the newly expanded brass through a .280 Ackley Improved resizing die.
Or, just buy loaded factory ammo from Nosler. I’ve been shooting a .280 Ackley built by Rifles Inc. for more than 12 years, and it remains one of my most accurate, deadly, efficient and fun big game rifles, having accounted for sheep, elk, moose, mule deer, whitetails and coyotes.
Another terrific Improved cartridge is the .22-250 Ackley. My Holland Custom Model 700 thus chambered easily pushes 55-grain Sierra BlitzKings to 3,850 fps, compared to 3,650 fps in my standard .22-250 M77 Ruger. The .22-250 Ackley Improved is essentially a .220 Swift without the case-stretching problems.
Of course, if you improve the Swift...
Gunmaker Darrell Holland likes the above, plus the 6mm Remington Improved (“Maximum bore-to-powder ratio for a 6mm and shoots 95- to 107-grain bullets very well.”). He’s also fond of the .250 Savage Improved (“Great deer and antelope round in a short action.”).
Here are a few more popular, efficient and useful Improved cartridges with their originals:
.22 Hornet to .22 K-Hornet
.243 Win to .243 Winchester
.257 Roberts to .257 Roberts
.30-06 Govt. to .30-06
.375 H&H to .375 H&H
There are many, many more, and die makers such as Redding, Hornady and RCBS stock and can quickly make reloading die sets for them all. I counted 10 AI dies in the 2007 Redding catalog. The gunsmith who rechambers your rifle can probably rechamber your standard loading die, too, for a true custom fit and precise headspacing.
Costs for the job might be as low as $150 at some ’smiths. Holland gets $250, but then he doesn’t just ream out the new chamber dimensions and call it good. “I also face the receiver square to the bore, remachine the locking recesses, surface grind the recoil lug and machine the bolt lugs.” All this maximizes accuracy potential, of course, and that’s worth a lot.
There is no magic in an Improved cartridge. In most cases, one or more new factory rounds will equal or exceed Improved cartridge performance. The 7mm Remington Short Action Ultra Magnum, for instance, virtually matches 280 Ackley velocities, and does it in short-action rifles, which are arguably (and minimally) faster and more convenient than standard actions. But rechambering your old .280 Rem to 7mm Rem Short Action Ultra Mag means cutting back the barrel, modifying the bolt face and the magazine. And you’ll still have a standard-length action.
If you’re buying a new rifle, of course, you should get one chambered to meet your needs. But if you’ve got a perfectly good older rifle/caliber that could be upgraded with an Improved chambering, you could get new rifle performance for very little cost. Check various handloading manuals for performance information. Not all list Improved cartridges, but many do, and these are convenient places to compare performance numbers against standard cartridges. Then talk to your gunsmith for his opinion. You could be the first kid on your block to shoot an Improved cartridge.
Reprinted from the July 2008 issue of Buckmasters GunHunter Magazine. Subscribe today to have GunHunter delivered to your home.