This Kynoch drawing dates back to 1913, according to Dr. Ken Howell's book: designing and forming CUSTOM CARTRIDGES for rifles and handguns:



Notice that the shoulder on the 430 Gibbs Nitro is 37 degrees instead of the Rigby 45 degrees, and the base to shoulder distance is a bit shorter than the .416 Rigby.
Otherwise it is a .416 Rigby necked up to accept .435-caliber bullet.
176 grains is what the external volume of the case would be in water weight.
1498 grains is what the case would weigh if it was solid brass.

The 404 RIP is similar, but has a base to shoulder distance same as the .416 Rigby,
but with a 20-degree shoulder angle, like the .338 Lapua.
Just decreasing the shoulder angle from 45 to 20 degrees at same shoulder start location thus increases the case capacity,
and lessens the chance of collapsing and bulging shoulder in reloading,
and makes the feed slicker:

.416 Rigby Improved

Then, necking it up to .423 increases the capacity a tiny bit more, PLUS adding bullet diameter:

404/.416 Rigby Improved Plus aka 404 RIP

In a Dakota M76 African or CZ 550 Magnum, it is a "40-caliber-plus 5-shooter" but no, it will not be called a "405 RIP."

Neither is the 404 Jeffery, a "40-caliber-plus of 1905," called a "405 Jeffery."

The 320-grain GSC HV bullet is actually .424" diameter on the driving bands, in the lot I received, way back when.
It is perfect for my McGowen barrel that is about .4245" in the grooves.
It is also perfect for the geometry of the 404 RIP cartridge case, neck and shoulder relationships,
when seated to 3.750" COL, in a 3.8" magazine box.

Those McGowen barrels also shoot all the .423" diameter North Forks to perfection in my 404 Jeffery rifles.

Test fired yesterday, the first 404 RIP on a Dakota 76 African, fireformed brass dummy:



Case capacity at 2.900" case length = 131.6 grains water gross with Norma .416 Rigby brass.
Norma .416 Rigby Basic brass with blank headstamp is "404 RIP" engravable, and I have 100 pieces of that.

Bullet length of the .424/320-grain GSC HV: 1.338"



QuickLOAD for that 320-grainer with 23" barrel:

RL-17 108.0 grains: 2901 fps MV, 5978 ft.lbs KE, 58,709 PSI, 97% fill
RL-17 109.1 grains: 2929 fps MV, 6096 ft.lbs KE, 60,750 PSI, 98% fill
+/- 30 fps per inch of barrel length

H4350 Extreme 110.0 grains: 2878 fps MV, 5885 ft.lbs KE, 56,792 PSI, 105% fill
H4350 Extreme 111.1 grains: 2909 fps MV, 6014 ft.lbs KE, 58,913 PSI, 106% fill
+/- 28 fps per inch of barrel length

Varget Extreme 100.0 grains: 2805 fps MV, 5589 ft.lbs KE, 58,008 PSI, 98% fill
Varget Extreme 102.0 grains: 2855 fps MV, 5793 ft.lbs KE, 61,715 PSI, 100% fill
+/- 28 fps per inch of barrel length

I am going to try those three powders to see which is closest to reality.

Slower and lower pressure with heavier bullets is easy,
with about a 15% case capacity advantage over the 404 Jeffery,
could easily be reduced to "Doctari" super killer.

The 404 RIP is a beauty!

Very nice looking cartridge RIP! Should be very deadly.

quote:

Originally posted by Canuck:
Should be very deadly.

Thanks, Canuck.
That's another reason it is called the 404 "RIP."
The initial fireforming loads were merely 96 grains of H4350 with 400-grainers.
Gentle as a maiden's carress on my end of the rifle.

quote:

Originally posted by RIP:

quote:

Originally posted by Canuck:
Should be very deadly.

Thanks, Canuck.
That's another reason it is called the 404 "RIP."
The initial fireforming loads were merely 96 grains of H4350 with 400-grainers.
Gentle as a maiden's carress on my end of the rifle.

LOL. I do like the name. Tres a propos.