Keeping Up With Cartridges

Buy A Bigger Gun Safe — Or A New Barrel!
2

His Pump’r Thump’r in .375/9.3x62 helped John Dustin take dangerous game including lion and elephant.

“That can’t be right,” thought I, but another count yielded the same sums. Just the first 18 years of this century have coughed up 50 new centerfire rifle cartridges. During the entire 20th century, from the debut of the Mannlicher-Schoenauer rifle to the Remington 700 in .300 Ultra Mag, there were 80 new cartridges.

Yes, the numbers just happened to come out even and yes, totals depend on exactly what’s counted, but — all this to say we’ve had a blizzard of cartridges lately. Fifty in 18 years! Just 88 from the advent of smokeless powder and the Dalton gang’s bank raid in Coffeyville, Kansas, to the year Bill Gates left as Microsoft CEO and America Online agreed to buy Time Warner!

John Dustin’s “Pump’r Thump’r” is a Remington 7600 re-barreled to .375/9.3x62.
A potent pump for snarling beasties!

Do The Math

You’d have to snare three rifles a year to keep pace with new chamberings now. Finding those rifles can itself test your resolve. I borrowed a Ruger in .376 Steyr, but after returning it have yet to see another. The .475 Turnbull appeals to me; outside Doug Turnbull’s shop, however, it’s a ghost. A rifle in .400 H&H has proven elusive too.

The 6mm Creedmoor, 6.5 PRC and .300 PRC arrived at once, like a gaggle of relatives surprising you at your door. Good news only if you can do something with them. The days when I had time to explore wildcat rounds seem as distant now as the need for wildcats.

The .450 Alaskan adds muscle to a Winchester 71 in .348, however,
re-barreling a 71 now dismays collectors greatly!

Make Your Own

My itch for a 6.5 PRC came after a glimpse of the Hornady cartridge and a visit to SAUER’s plant in Germany. But no U.S. rifles were so chambered but then the wildcatter’s path came to mind — why not re-barrel? A standard short action wouldn’t work but enter an idle Weatherby Vanguard in .300 WSM, a cartridge much like the 6.5 PRC below the shoulder. I phoned John Krieger, who knows more about barrels than anyone else I can think of. “It should work,” he agreed.

It did. The new barrel, contoured to match the old, snugged nicely in the original stock. The rifle feels the same and shoots even better.

Krieger barrels have earned high praise, not only on custom rifles but in ballistics labs. Held to 0.0001″ groove tolerance, the cut-rifled bores are hand-lapped. Uniformity is checked with an air gauge, a moving probe using air pressure to “feel out” variance to 50 millionths of an inch! John is fussy about throats too. “A parallel throat is like a piston sleeve. It can’t be oversize, but must accommodate all bullets,” he notes.

As long throats keep a lid on pressures, Roy Weatherby used them to hike velocities, maintaining accuracy with close tolerances. Of course, muzzles matter too. Krieger lops an inch from each barrel before crowning, as “bore finishing can leave a flare.” His barrels are also cryogenically treated, to relieve stresses imposed by turning and rifling. The 6.5 PRC project reminded me how a new barrel is, in effect, a new rifle.

A new or rechambered barrel is still the only road for wildcatters but now you’ll be hard-pressed to come up with a useful round yet unexplored. Indeed, performance overlaps have given way to downright duplication! So with factory offerings galloping by at a rate of 50 every 18 years, why invent?

When choosing a load for a re-barreling/re-chambering project, make sure the box accepts loaded rounds!

Pump And A Thump

“It’s a slide-action .375.” A rifleman with the savvy and tools to do much of the gunsmithing we mortals farm out, John Dustin is no slave to tradition.

I shifted the phone to my bagel-free hand. “What for?” I asked stupidly, as if a new rifle required purpose.

“Dangerous beasts,” he replied patiently. “Five haymaker hits lickety-split.”

Hmm. The only slide-action centerfire rifle still in common use is Remington’s 7600, offspring of the 760 Gamemaster introduced in 1952. Its mechanism, sized for the .30-06, can’t digest the long, belted .375 H&H. Needlessly I pointed this out, noting pump guns, while fast with repeat shots, can’t match the reliability of bolt rifles.

“Yes, yes,” sighed John, as if having to explain again why bread comes warm from a toaster, “My Pump’r Thump’r isn’t barreled for that .375. But it is reliable — and quicker with five shots than any bolt gun.” He added each bullet carries two tons of muzzle energy, “almost what you get with 300-gr. factory loads in the .375 H&H.”

Like me, John had admired the handling qualities of the old 760. “A few years ago,” he went on, “I bought a 7600 in .308, set the barrel back two threads to shorten the throat, tuned the trigger, installed one of my JD Quietbrakes. The rifle shot into a minute of angle.”

Necked to .375, the 9.3x62 (center) can push 300-gr. bullets at 2,450 fps,
almost as fast as the .375 H&H (right), from a .30-06-size action!

The ‘Why’ Answered

A leopard hunt with a few frantic moments prompted John to think about a pump for dangerous game. To meet legal and practical requirements, it needed at least a .375 bore. Remington had barreled the 7600 for the .35 Whelen, which could be opened to .375 but the 9.3×62, a European round dating to 1905, had essentially the same head diameter with 5 grains more capacity. Bumping the neck from .366 to .375 was easy. Dave Skiff at Pacific Tool and Gauge made a reamer for John’s wildcat. Hornady sent custom dies.

“I bought a new wood-stocked 7600 in .30-06,” said John, “then shaved the comb for iron-sight use and installed a Pachmayr Decelerator pad.” He also opened the forend to accept the .375 Pac-Nor #5 barrel he’d chosen. “It’s heavy enough to keep the muzzle down in recoil and speed follow-ups.” Dustin also added a JD Quietbrake then fitted a Williams ramp front sight. An XS rear aperture clamps to the Weaver scope base under his Burris 1.5-6x, in low rings. Finally, he tuned the Pump’r Thump’r’s trigger.

John tried a variety of bullets in the .375/9.3 with an eye to fault-free feeding and the hardest hits possible given length limits imposed by the 7600’s magazine. He settled on 300-gr. Sierra GameKings for thin-skinned game, driving them 2,450 fps with 60 grains of Varget. “I started with lighter bullets around 2,600, but the Sierras delivered the best accuracy and flew about as flat. The charts show 2,500 ft lbs. at 350 yards!” Testing solids, he came to favor 300-gr. Woodleigh and Hornady bullets. He told me he coated all bullets with molybdenum disulphide as loads with uncoated bullets must be reduced to keep pressures in bounds.

One of Wayne’s favorite cartridges, the .25 Super is a necked-down .308.
Wayne gave Charlie Sisk a Remington 78 to re-barrel and was mighty pleased with the result!

Big Gray Proof

Given the Pump’r Thump’r’s intended use, John practiced shooting as if at dangerous beasts bent on mayhem. “All offhand and close.” His drill: five aimed shots in six seconds. “I broke five clay pigeons at 30 yards in eight seconds.” Yes, they were stationary but do the math: His Remington hurled 20,000 ft lbs. of heavy-bullet energy about as fast as even skilled hunters can fire three aimed shots from a powerful bolt gun! John and his new rifle were soon bound for Africa.

In parts of Zimbabwe, elephants are so plentiful they must be culled. Permit in hand for a tuskless animal, John got his chance early after tracking a small herd. The lead cow had no ivory. She turned and faced him at 15 steps — and collapsed instantly when the Pump’r Thump’r sent a Hornady DGS through her brain. “I ran up and fired another shot to the spine,” said John, “but it wasn’t needed.” The first bullet had exited the back of the skull. “We recovered the second. It had severed the 8″ spine and traveled the depth of the elephant. It held its shape and weight. I could have reloaded it!”

The Pump’r Thump’r would see other action, which for want of space I can’t recount here but it reminded me an ordinary rifle with a new barrel is really a new rifle!

Subscribe To GUNS Magazine