From: Powder Keg, R. Seyfreid, Handloader #230, August 2004
"Q: I am trying to get loading data for the .450-400 3-inch Nitro. I am shooting both cast bullets and 400-grain Woodleigh bullets in Bertram cases. I also need to know about the Dacron filler. Do I need it in the .400?"
A: There are two variations of the .450-.400 x 3-inch cartridge. The "trade" model had a thin (.040-inch) rim and normally used 60 grains of cordite with a 400-grain bullet. Jeffrey used a thick rim and only 55 grains of cordite. Either one likes the 1.19 multiplier of Reloder 15, with a Federal 215 primer as a duplicate to the original full-power loads. That is to say, 1.19 times the 55- or 60-grain cordite charge. Normally, you do not need Dacron in the .400s. However, if you experience any form of hangfire (this will probably be as minute as your thinking you can hear the hammer hit before ignition), add 3 grains of standard polyester pillow stuffing over the powder. This load is compatible with the Woodleigh softpoint bullet. If you use their solids, reduce the powder charge 2 grains.
For cast bullet shooting in the .400s, we discover a wonderful phenomena in cordite double rifles. Against all conventional wisdom, they will usually regulate perfectly with a very reduced load, by simply pretending they were black-powder rifles. Now we turn to the nitro-for-black-powder formula. The 3-inch case was not a black-powder round, but its 3¼-inch older brother was. It normally used 100 to 110 grains of black and 230- to 260-grain bullets. Hodgdon 4198 is the powder of choice. The formula is now 40 percent of the black powder weight.
Load with a standard Large Rifle (not magnum) primer and begin with 42 grains of 4198. The nitro-for-black loads must use Dacron; 10 grains will be correct, over the powder. Add a hard 230- to 260-grain, .41 Magnum pistol bullet and you will have a nice, friendly deer load. Most rifles regulate perfectly, although it is often necessary to use the 200-yard sight leaf to get correct elevation at 100 yards."
Note: In Miniature Black Powder Express Cartridges, Handloader #225, Seyfried states the Dacron must fill the case and not be tamped down on the powder as a wad.
From: Reloading the Nitro Express, R. Seyfreid, Handloader #202, December 1999
"Unlike the earlier black-powder rifles, most nitro rifles will have the service load stamped on the barrel flats as part of the proof marks. This usually specifies a maximum load of cordite and bullet weight. One usually encounters something like "cordite 70-bullet 480 max."
"Slug the bores and make chamber casts before you buy components. Finally be sure you are indeed working with a "full-cordite" rifle. Many unknowing or unscrupulous sellers call every British express rifle a "Nitro Express". If the barrels do not show the cordite charge in the proof marks, they are probably made for black powder."
"The correct powder for the nitros is also surprisingly simple. Most who are serious reloaders for the nitros have distilled the selection to one powder: Alliant Reloder 15. You will see and hear references to other powders; IMR-3031 and some of the very slow ones like 4831 have been used. In my experience IMR-3031 has a shrewish temperament in the big cases, demonstrating rapid pressure rises. The slow powders have blown the sides out of more than one set of fine double barrels. No one has a precise answer to "why?". Because it has happened, I treat the slow powders like the standard medical formula, "Doctor, it hurts when I do this." Reply: "Do not do this!"
"Returning to our chosen fuel, RL-15, its use and perfection was invented by none less than Federal Cartridge for their own .470 Nitro cartridges. It is a mild-mannered, delightful powder that re-creates original ballistics, right across the spectrum from .450-400 to .600, using the same conversion formula. That is, multiply the original cordite charge by 1.19 to substitute RL-15. In almost every instance, caliber and rifle, the velocity, with the correct Woodleigh bullet, will be right in the Kynoch window. (It is a good idea to begin two grains below the calculated charge, just to be on the safe side.)"
"The one compromise with RL-15 is that it takes up less space in the cavernous cases than did the original spaghetti-like cordite. To obtain perfectly crisp ignition, one must add a small ball of Dacron (polyester) fiber filler. Most .40- and .45-caliber rounds want four or five grains, while the .470 and .500 use six or seven grains and the .577 and .600 take seven or eight. Loads without the filler can demonstrate minute, but disconcerting, hangfires. Those with fillers are crisp with uncannily uniform velocities."
.450/.400-3 inch - 60 grs. Cordite - 400-gr. bullet - 2125 fps - 71.4 grs. RL-15
.450/400-3¼ inch - 60 grs. Cordite - 400-gr. bullet - 2150 fps - 71.4 grs. RL-15
