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.375 Durham: Power!
November 2002
Gerhard Schroeder


“Won’t plink with this rig!” That was one of the immediate thoughts after launching the first 270 grains of lead and copper alloy, driven by 65 grains of IMR 4895. Then again, it really wasn’t that bad. Yes, there was no denying that the gun had gone off, but at least I remained in the same zip code.

What happened? A hunger had developed, slowly but undeniably, for a rifle with more horsepower than the average ’06, 7 Mag or whathaveyou. Rather than go Lazzeroni hyper fast, I wanted bullet mass, and no buffalo .45 slow-mover either. Such keen reasoning settled on a hole in the muzzle that would measure around .375 to .416 inches. Focused research could now commence.

Lookie here, some talented individual(s) came up with this entire class of “Hawk” chamberings, all based on blown-out 30-06 brass to, well, anything you want on up to .411. These are not merely .35 Whelen style. The shoulder is moved forward for more powder capacity. Interestingly, the .375 version claims to reach within about 100 fps of the .375 H&H, at least with bullets around 250 grains. Well, that was good enough for me, and the plan was hatched.

I picked up a ‘project gun’ on my very next trip up north, stopping in that first “candy” store in Prescott Valley on the north side of the road, and leaving with a 30-06, for two bills out the door. The Mauser 98 action, superb trigger and modified bolt handle to accept a low scope mount made the deal. I also lined up a gunsmith, had selected what Shilen barrel I would order, and located a source for the chambering reamer.

Then it happened, just in time. At the next Crossroads Show, three numbers caught my eye: “375”. Sure enough, here rested on wooden pegs, a custom Santa Barbara Mauser, in .375 Durham Magnum, with Bell & Carlson composite stock, Douglas Premium barrel, Magna Porting and Williams peep sight. Nothing is perfect! This baby sports only 20 inches of barrel, where I would have wanted 25 or 26. Neither did loading dies or loaded ammo accompany the proposed deal.

Initially, I walked from that table. However, after Herr Oberst (Mike Kelley) pointed out that I, wanting a big bore, would be a flaming fool (well, he said something to that effect) not to buy it. So I returned, and the Mauser went home with me for less than the Shilen barrel would have cost on the ‘Hawk’ project.

Needless to say, that ‘Hawk’ project was instantly cancelled, and the ’06 soon re-sold. So, what’s a Durham Magnum? Herr Oberst shed light on this one as well. The great P.O. Ackley, in his Volume I ‘Handbook For Shooters & Reloaders’ tells us on page 483 that Mr. Durham started with a .338 Magnum, necked it up to .375, and blew out the shoulder to 35 degrees. And when you do so, you get .375 H&H velocities even from a 20” barrel. Right On!

But wait, no dies yet. The horror story was that somehow I needed to load at least three rounds, fire-form them, ship the empties off, and some 250 bucks later a custom set of reloading tools would return. Then another strike of luck, for the latest 2002 MidSouth catalog features a double page of RCBS custom dies, and a .375-338 was on their list. It probably isn’t the Durham version, but should be close enough, and for eighty two dollars the order was placed.

Delivery time was way out there. I could not possibly wait that long to fire this dragon. Good friend and hobby gunsmith Ron crafted an expander, and a sort-of seating guide, and sure enough, at a snails pace I could assemble the first fat rounds. Refer to the beginning of this story for the results.

On our second outing we employed a chronograph. Encouraged by the initial firing and lack of any pressure signs, I had notched up some loads to 72 grains of RL15. Turned out that 65 grains of 4895 gave 2400 fps, 67 grains increased that to 2500, and the winner was RL15, launching the 270 grainers at slightly over 2700 fps when 72 grains came uncorked. That’s certainly enough gun for me, and pretty much a match for .375 H&H performance, whereby the oldie needs both more powder and barrel length to make the 2700 mark, at least according to published figures.

One thing happened, however. The RL 15 load actuated the hinged floor plate. Removing the barreled action revealed a cracked stock in the area between magazine and trigger cutouts. Was that at least one reason for the rifle’s low sales price? Another trip to Ron was in order. We agreed, since space permitted so, to mill out two small ‘ditches’ perpendicular to and across the cracks, buried two screws minus heads in a bed of JB-Weld in those ditches, and covered all that with an aluminum plate.

Later I went one step further, stuffing JB-Weld in a syringe to squeeze epoxy in the gap between steel magazine box and stock. Furthermore, the ‘spirit’ of this rather light and compact weapon (for its caliber anyway) demanded a special scope. The winner here was the fixed power 2.5x Leupold.

Arrival of the die set coincided with June hell weather, and World Cup Soccer. At least Germany came in runner up! Eventually I got around to the .375 project again. Turns out that the dies work just fine. Hating to full-length size anyway, I now get by with partial sizing, not touching the fire-formed shoulder, but resizing plenty of neck length to hold the fat slugs firmly in position.

The stock repairs worked. The floor plate no longer comes flying open. The stock is stiffer now, and so is recoil. Still, the gun is manageable. Accuracy testing was limited simply because I can extract little fun from shooting this cannon off the bench. Besides, the metalwork demonstrates that whoever built it knew a thing or three about custom rifles.

I forgot to mention, this custom Mauser is matte finished all over. There is not a single spec of shining metal on the piece. That’s certainly how hunting tools should be, “all business”! This weapon is awesome. Light, short, balanced, yet mean-looking and capable to dish out foot-pounds and knockdown. I just dread the moment I’ll have not enough time to stick in earplugs.

A couple 1¼” groups proved indeed that this Mauser would shoot bullet weights of 200, 220, 235, 260 and 270 grains well enough for drawing big game blood. Here are a few numbers: (again, fired from the 20” barrel; all used Remington large magnum primers):

200 gr Sierra FN 40 gr IMR 4227 2200 fps
62 gr IMR 4895 2310 fps
64 gr 2400 fps
66 gr 2500 fps
68 gr 2600 fps
220 gr Hornady FN 68 gr IMR 4895 2570 fps
235 gr Speer SP 68 gr IMR 4895 2550 fps
260 gr Nosler Bal Tip 70 gr RL15 2710 fps
270 gr Hornady RN 72 gr RL15 2720 fps

From then on I much preferred to shoot at ‘stuff’, such as a steel plate, or black rocks (where the bullets leave obvious impact marks). Such off-hand training is of a lot more value in preparation for hunting than punching paper. Pick a rock, quickly decide how far it may be and how to hold, and fire.

What about the power? For sure, you can ‘feel’ it every time a slug leaves the muzzle that this isn’t your average ‘06. And the bullets rip up a lot more dirt ‘n dust when they encounter the hillside. Similarly, they have penetrated every dead tree I’ve tried in the desert. In short, the Durham version churns up every bit as much hurt as a regular .375 H&H would.

Deviating from that path slightly, lightweight 200 grain Sierras, throttled down to 40 grains of IMR4227, proved plenty accurate, a nice bonus that someday may down a deer during a woods hunt. This load is almost OK for plinking. It certainly is not punishing to shoot. I may explore these lighter projectiles some more, to determine if they are flat-shooting enough to do duty even for a high desert deer chase. Either way, there’s a real powerhouse residing in my arsenal now!

Let me close with more absolutely delightful news (for me, anyway). The Game and Fish answering service revealed late on a Sunday night that both a deer and an elk permit are coming my way for 2002. While the deer hunt is my third choice, equating to open desert terrain, the .375 Durham will certainly see duty in the cow elk woods. I’m itching . . .

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