I guess I really never realized exactly how massive the 475 is. I picked up a Kynoch 475 No 2 J. Nitro at a show today and now I can better understand how this is truly a stopper in a well-balanced double. I'm sure this is all common knowledge for most of you here, but just for giggles I scanned a line-up starting with the 475, 375 WBY, 375 H&H, 300 H&H, and the 30.06. When I hold the 375 along with the 475, it feels more like a 257 Roberts. Man oh man I would hate to be a buff on the receiving end of a 475 at 10 paces. I don't know how anything couldn't drop like a hot bisquit after that.

Just for the record, the english cases in that era are always huge, due to powder ... and the germans had flake powder, which allowed them to make smaller rounds... 505 gibb vs 500 jeffery

475 express-483 bullet, btw.

and, frankly, 450 NE to 475 NE (and all the ones in the middle) are 500gr at 2150 ... about 9, irrc, different rounds that do exactly the same thing...

and some folks complain that theres too many "copycat" performance rounds today!!

jeffe

That 475#2 Jeffery you have there is a fine round. The .488 bullet is one heck of an elephant killer. I have reloaded and shot that round for my friend David. He has taken several elephant and buff with the rifle.

Just on the cuff of what I can take in recoil. In an 11 lb. rifle it is not unpleasant to shoot.

Rusty knows doubles better than me... the 475#2 is the 488, and the 475 WR is the 483....

and someone asked me why I didn't call the 470 AR the 475......


cuz .470 XXX means .475 bullet!!
jeffe

quote:

Originally posted by jeffeosso:

and some folks complain that theres too many "copycat" performance rounds today!!

Agreed, but at least then you had the legal justification for coming up with something deviating slightly from .458 cal rounds OR developing lower pressure equivalents of the original .450NE during the uneasy transition from black powder. Sure, there was a strong element of proprietary cartridge mania then but at least is was partially fueled by something external to itself...unlike today.

JMHO,

John

That 475 is just massive. It makes everything else look small. The 375 WBy and 375 H&H look very close to each other and the case capacity doesn't look that much different. I know all the debate between the two and for how similar they look, it surprises me that the Wby offers 150-200 fps more than the H&H.

Prewar,
your 375HH is loaded to 55kpi, and the Weby to 62.5kpsi (on a slightly larger case)

the NE are generally loaded from 14.5 to 18 tonnes (notice the word 2205 LBS, not 2000lbs) or roughly 32kpsi to 39.7psi

for example, the 470NE and the 470mbogo have nearly the same case capacities, one loaded to 55kpsi, gives a 500gr bullet 2500fps... loaded to 39kpsi results in the same bullet going 2150 ON A GOOD DAY using historic loads.

so, just because the case is huge doesn't mean it's going to be a HIGH velocity whomperstomer ... but it is designed to operate in the low 2000fps range


jeffe

Jeffe:

Not exactly. There's a common misconception in play here. You've compared apples to oranges.

KPSI and CUP are measurements of chamber pressure, which is measured radially (on the chamber side-wall) via piezo electric transducer and copper crusher respectively. They're different yardsticks for measuring the same thing - chamber pressure.

The flanged Nitro Expresses were designed, developed, and standardized by the British. With respect to centerfire rifle cartridges, the British didn't measure chamber pressure - because they didn't consider it to be the critical variable with rifles, especially doubles. Instead, the British tested pressure in base crusher guns. These measure the amount of pressure exerted by the case head against the breech face, via copper crusher. Thus, the standard pressure for these cartridges is stated in long tons (2240 lbs/ton, not 2205) of bolt thrust, NOT chamber pressure. A .470 Nitro Express has a standard pressure of 14 tons bolt thrust, not TPSI, not CUP. The three are not the same, and are not readily convertible to each other. As these cartridges began their return from the dead in recent times, the British standards were universally misunderstood. This is why factory ammunition (and "pressure tested" reloading data in some published manuals) in recent years has often been overloaded. Today, Kynoch's pressure guns are still base crushers, with a piezo electric transducer in the chamber wall. They load to the base crusher as they always have, but also record the piezo data, as that is the current CIP standard.

Remembering your strain-gauge rig, I thought you might find the above of interest.
---------------------------------------------------------------------------------
"Serious rifles have two barrels, everything else just burns gunpowder."

Yeah . . those #2's (450 & 475) are certainly lookers. However, keep in mind this, the various 450's in 480 grain have better sectional density than the 475's.

John " Pondoro " Taylor once opined, concerning these massive #2 cartridges, " Don't believe that you have anything like the Atomic Bomb to play with. You don't."

These large, heavy cases were designed to minimize case expansion in the heat of the tropics, however, they were not necessary.

The 500/450, 500/465, 470, and others are just as effective.

The UK system of copper crushers measuring from thrust on them,
by the bolt face was/is still converted to tons per sq in,
or further to psi....They are not direct bolt thrust figures.
Bolt thrust can be derived from the lbs per sq in, by taking
the area of the base and times psi, times 2/3.........I mean a full
house bmg load puts 24,000 thrust on whatever kind of breech the
gun has.And designersset up bmg bolts with ashear rating of 3 times that.
My Savage 12ga FH max load has less than half of that
bolt thrust. A H&H based case at 60,000 psi has 8400 lbs bolt
thrust. It would really be nice if those NE doubles could operate
at pressures of 16-18 long tons actual breech thrust, as gun designers
build in a 3 to 1 safety margin on thrust. But they aren't
that strong or we'd solve strength problem of putting our
12GA FH in break actions very easy. For example a cartridge with
16 tons of psi to have 16 tons of breech thrust, the base of the cartridge
would have to be 1 sq inch in area, say as big as my
2 bore case.A case like 600NE has only .29 sq inches of base area.
And best use for 475 #2 cases are straightened out to
50 cal, like my 510HE. Use rimmed, real neat in
Ruger #1.Ed.