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.375 Flanged Nitro

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The year 1912 was a hallmark year for those of us who love the sport of big game hunting. Holland and Holland introduced a cartridge into their family of sporting cartridges, which became the standard for big game hunting throughout world, and a cartridge design that fathered an unending family of cartridges featuring the new belted case design. The .375 H&H belted magnum was 100 years old in 2012, and is still going strong.

1912 was also the period of great game hunting in Africa. World War One was still in the distant future, and the world was made aware of the challenges of Africa from some of the greatest adventure writers ever known. Most of that generation grew up with the stories of writers such as H. Rider Haggard burnt into their young minds, and a desire to travel to the vast plains and shooting fields of Africa.

Much has been written about the .375 H&H belted case, however many are not aware of the contribution of its sibling, the .375 Magnum Flanged Nitro Express, which was also born during that fateful year.

From left to right: .357 160-grain cast bullet, .377 swaged , .357 bullet, 248 grain plain base, 252 grain gas checked, 268 grain gas checked, 278 grain gas checked. 375 Magnum Flanged, .375 H&H belted, .375 Magnum Flanged with 278 grain bullet

In 1899, the British developed a predecessor, which was known as the .375 Flanged Nitro Express. This cartridge featured a straight-rimmed case with a length of 2.5 inches and a rim diameter of .523 inches, and offered ballistics quite close to the .38/55 cartridge. This cartridge, even though almost unknown in the United States, can be encountered in rifles still in shooting condition. Even though the ammunition is no longer manufactured, anyone wanting to reload this caliber can fabricate cases from new Hornady .405 Winchester cases or use .30/40 cases. The .30/40 case ends up a little short by about .250 inch, but is still very usable.

The cartridge in this family that I love the best is the .375 Flanged Magnum Nitro Express. Holland and Holland realized the ballistics of the .375 H&H would make it a winner in the game field. However, they also had the wisdom to realize a rimmed case was much more reliable in the single shot and double rifles, which were popular in those times and places, where the animal could, and possibly would, turn the game plan against the man with a non-functioning weapon.

I give full credit and respect to the belted .375 H&H magnum. However, there is nothing that you can take into the field that has the feel of a good double rifle. The doubles like the rimmed cases, and the .375 Flanged Magnum Nitro Express is a sibling brother to the .375 H&H, except that the case is longer and it has a rim. I know of no other cases that can be formed into this case. The case length is 2.94 inch and the cartridge has a rim diameter is .572.

Holland and Holland decided that due to the firearms design and metal of the day, this cartridge should operate at a pressure just below that of the .375 H&H. The fact that the cordite powders of the day were temperature sensitive in the heat of Africa and India also had a lot to do with this decision. Today, most modern double rifles and powders can handle this level of pressure and in theory, the flanged version of the cartridge can match the performance of the .375 H&H belted Magnum and be reliable in a double rifle with either extractors or ejectors.

A family of champions. Left to right: 9.3x72R, 9.3x74R, .375 Magnum langed, .450/400 3-inch, .450/400 3.25-inch, .470 Nitro, .475 No. 2 Nitro Express, .500 Nitro Express, .577 Nitro Express, .600 Nitro Express, and the ‘Big Daddy’ .700 Nitro Express

My personal .375 Flanged Magnum Nitro Express was built by Butch Searcy of Boron, California, and forms a mate with the original set of .470 Nitro Express barrels. I enjoy the .470, but it is a little large for informal shooting here in the United States. The .375 Flanged Magnum barrel set gives me a smaller caliber that can be downloaded for local hunting and target shooting. Kynoch, as well as a few European manufacturers, loaded the original cartridges. These originals now sell for up to ten dollars each and were mostly Berdan primed.

Various manufacturers have produced a few recent runs of boxer-primed cases, which are reloadable with normal components. These limited runs seem to sell out overnight, and then be forgotten in the shadow of new and more modern cartridges. Shooting factory ammunition for fun and practice at these collector prices is out of my budget, and jacketed bullets are still more expensive than most smaller caliber projectiles.

The answer for those really wanting to shoot this caliber in volume is to reload with cast lead bullets. I want to shoot this rifle this hunting season, so I have been working for the last two weeks on re-establishing load data. The .375 Flanged Magnum barrels are fitted with a Leupold Vari-X III 1.75x6 scope with a heavy duplex reticule, and Warne quick detachable rings for the integral barrel mount.

Over the last couple of years, I had worked out some fun shooting loads using .358 caliber 158-grain cast bullets that had been tumble lubed and then bumped up to .376 diameter on a old C&H Swagematic press. Using several different fast burning powders in loads from 9 to 12 grains they were great shooters at 25 yards for offhand practicing on an indoor range.

The gun is so much fun to shoot with these loads, that I convinced myself I want to take it deer hunting this year using cast lead bullets in a area were it is still legal to use traditional lead base ammunition. This is difficult to find in California nowadays, and may be impossible some day in the future, so if I want to do it, I decided that now was the time before the anti-hunters have their way to further restrict the hunting sports.

This is what you see from the breach. Left: 470 Nitro Express. ight: 375 Magnum Flanged

I have been using several different cast lead bullets as a base for a hunting load. My first run was with the Lyman #375248, which weighs 249 grains, after sizing to .376 and lubing. The second bullet is the Lyman #375449, which uses a Hornady gas check and as a finished bullet weighs 277 grains. Both bullets were casted using wheel weights, plus 2% tin, and water quenched directly from the mold into room temperature water. I also had on hand a number of old .375-inch bullets that were left over from testing other molds I found at different gun shows.

Since the idea for these bullets is not to just have a mild indoor shooting load, but to also have something with a much higher power setting for field game shooting, I decided to use mostly heavier loads of slower burning rifle powders.

The .375 Flanged Magnum Nitro Express is so similar to the .375 H&H that, except for the longer neck and rim on the flanged cartridge, you can call them clones of one another. As mentioned earlier, the flanged case is often used in single shot, light weight, break top rifles of early manufacture, and is usually loaded to lower pressures then its belted brother. They are so close that you can even use the same set of loading dies for both calibers, as long as you remember that the flanged brother has a longer neck. You must take that into account when setting your dies, especially the seating die. I actually use a .375 H&H die for seating the extremely short 158-grain bullets into the flanged case.

The .375 Flanged Magnum Nitro Express is not the easiest caliber to find cases for here in the United States. Many doubles have been built chambered for the .375 H&H belted cartridges; however, I believe that a double is best served with a solid rimmed cartridge. I would not want the ejectors to jump over the rim of a belted case in those situations where a double rifle is at its best.

The Lyman 4th Edition of their cast bullet handbook does not list the .375 Flanged Magnum Nitro Express. In fact, hardly anyone lists this cartridge and loading data is very scarce. However, the good news is starting loads for the .375 H&H seem to be in the ballpark for this less popular brother in a strong double rifle. The recommended cast lead loads for the .375 H&H are in a pressure range that is very compatible with most of the older, weaker rifles in this caliber. Besides, the best results with cast lead bullets are in the lower pressure windows.

Lyman lists in this manual a fairly broad number of powders for the .375 H&H with lead bullets. I had four of the powders they had listed in my loading stock: IMR 4198, IMR 3031, Accurate 5744, and Alliant Reloader 7 (R7).

I started with the Alliant R7, since the only can of this powder I had was about 3/4 empty and it seemed to be a good way to use up what was left. I started shooting four shot groups, two shoots from the left and then two from the right barrel. Loads with the 277-grain bullet started at 26 grains and worked up to 34 grains. No loads showed any real signs of pressure, but you could feel the difference as you worked your way up. All loads shot nicely at 50 yards, so that was the range I set the point of impact. I settled on using the 34 grains load, since it was in the power range I wanted and actually shot the best group. I fired four rounds, two from each barrel at 25, 50 and 100 yards using a 3-inch bulls eye. Without any change of setting, all twelve shots were in the bull. Not bad for a double that is not really regulated for the load I was using, but now I had run out of my stock of R7.

This is the view from the game's perspective. Left: 470, Right: 375.

The next test run was with the same bullet, using Accurate 5744. I have always liked this powder and use in almost exclusively in the larger calibers with cast lead bullets. The starting loads were at 27 grains and worked up to 34 grains with the 277-grain bullet. Surprisingly, accuracy was on a par at 25 yards with the R7 loads. Then, I worked up one grain at a time to 34 grains. At 34 grains, the recoil level was becoming noticeable and the barrel really started to heat up after 10 rounds or so. In fact, when shooting over a 10 to 12 minute period, the barrel was too hot to handle. I noticed that for some reason the hotter the load the better the gun shot, and the separation of each barrel decreased as the loads increased, without the bullets crossing over. Also, this powder seemed to give a real flash of flame out of the barrel, but I did not notice any streaks of burning powder flying around.

Next came a can of IMR 4198. Again, started at 24 grains and worked my way up to 35 grains. This load speaks with authority, but seems to have a lower pressure curve than the Accurate 5744. The barrel flash seems less intensive and the load shot just as well. Accuracy again was surprisingly good at 50 yards. I have not had a chance to shoot out to 100 yards with this load, as again I ran out of powder. However, since I want to use this gun from a tree stand at 50 to 65 yards, I believe I have a couple of loads that I can use with confidence this season.

The next powder in my rounds of test shooting was IMR 3031. This medium burning rate powder has always been promising in other cast lead loads and seemed to be worth the effort. IMR 3031 shot just a well as IMR 4198 and Alliant R7, with the possible advantage that the barrel did not seem to heat up during the ten shot strings.

I will be working with the 249-grain cast lead Lyman bullet in a couple of weeks. This bullet does not use a gas check and will probably be a little cheaper to load in the future, considering the cost and difficulty of obtaining a steady supply of gas checks for the .375 bullets. I only have a couple of hundred of these to play with, but if they shoot as well at the heavier bullets, I may need to order another mold so that I can avoid the use of a gas check.

These tests with the .375 Flanged Magnum with cast bullets should be parallel with what you should experience with the .375 H&H. Anyone having the luck to own either .375 caliber will find these cast lead loads will make them into a manageable, pleasant shooting, deer or pig gun at ranges up to 125 yards or so. And, of almost equal importance, the cost of shooting will be right down there with any medium caliber handgun cartridge.

Leo Grizzaffi is a lifelong hunter and veteran of many African safaris. Author and reloading expert, his specialty is the care and feeding of big bore double rifles, however he also dabbles with the little calibers. Leo resides in California, where being a lawyer and judge in the City of Los Angeles sometimes interferes with his busy hunting and reloading schedule.

I hear rumors that Nosler may be considering making a run of loaded ammunition in the original 1899 version, .375 Flanged Nitro Express. If they do, I hope they will also make cases available for this fine old cartridge. Corbon is offering loaded .375 Flanged Magnum on their website for approximately $4.00 a round.

My advice is to load cast lead bullets and enjoy shooting this classic caliber. Let us hope it will be around for another 100 years.

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