Yes, very close, here is the load data and a comparison of POI's, that I have posted here before:
340-grain North Fork SP with 87.6 grains VARGET >>> 2706 fps
380-grain North Fork SP with 85.0 grains VARGET >>> 2525 fps
400-grain Kynoch FMJ-RN with 81.0 grains VARGET >>> 2400 fps
Three targets shot on the same day, at 54 degrees F.
VARGET Extreme is "Thermo-Ballistically Independent" (TBI).
Works same at hot or cold.
All loads with Norma brass and Federal GM215M primer, same as F-215,
All loads from 24" McGowen 1:10" twist barrel installed by Rusty McGee on my M-70 Winchester.
Tighter barrels or barrels of different twist may require different charges to get the same velocities.
First shot was fouler, next three for POI:



400-grainer and 380-grain North Fork were within 1/2" of same POI. Close enough for using heavier bullets up close and lighter, faster bullets out to 300 yards:



Saeed used VARGET and got even higher velocities/energies than I did, like you would with a tighter bore /groove, and different twist, slower twist, IIRC.
He had no pressure signs.
I had no pressure signs either.
Granted, an old antique standard M98 of "pre-war" steel might be better of with antique ballistics loading.

One could use the 380-grainer for DG at close range, and the 340-grainer at long range for plains game.
Just know your trajectory for the long range work and decide how you want both bullets to hit at 100 yards:
Dead-on or something like 1", 2" or 3" high for long range shooting.

320-grain GSC HV copper monometal goes a little faster.
That could be a Non-Con single bullet weight for DG or PG, just like CEB fly-weight brass bullets.

A quaint little comparison of the 404 Jeffery to the .375 H&H by the artifice of Sectional Density:


320-grain SD = .255 for a .423-caliber bullet (GSC HV).
340-grain SD = .271 for a .423-caliber bullet (North Fork SP).
380-grain SD = .303 for a .423-caliber bullet (North Fork SP).

250-gr/.375 SD = .254
270-gr/.375 SD = .274
300-gr/.375 SD = .305

Drive the corresponding (by SD) 404 Jeffery bullets as fast as the .375 H&H bullets, or faster,
and things work very well.

rip seems you can get close to the same terminal effect with a 458 win mag at 350 400 450

driving the 350 at 2650 fps

just saying

I have a .423 express [wildcat] off the 458 case as well

it works well and don't kick so much as a plus

but the 458 is so close using same wt bullets often I just shoot that and get on down the road

You the man. I started my 380 gr SS in my 404 at 2,400 (tried some loads up to 2,800) and thought I was ok. Well. 2,300 felt even better and might try 2,250. A 380 gr SS at 2,525 is a KILLER and has some real range to it - legit 300 yard round.

BTW - did you try H4350? That's what Northfork recommended. I'd like to try Varget at some point.

Well, I talked to myself until sumbuddy replied:

quote:

Originally posted by stradling:
rip seems you can get close to the same terminal effect with a 458 win mag at 350 400 450

driving the 350 at 2650 fps

just saying

I have a .423 express [wildcat] off the 458 case as well

it works well and don't kick so much as a plus

but the 458 is so close using same wt bullets often I just shoot that and get on down the road

2650 fps with a 350-grainer in a .458 Winmag?
A bit hot?

I used to think that 400-grainers at 2400 fps in the .458Winmag was unobtainable, 'cause back when all I had was IMR-4198 and RL-7,
I would get pierced primers, brass extrusion, and sticky extraction if I got that velocity.
Newer powders will do it better, I hear.

However, the .458 bullets of same weight as .423 bullets do not have the external and terminal ballistic advantage. The .423 wins.

.423/400-grainers at 2550 fps is an easy 60,000 psi load in the standrd 404 Jeffery.

quote:

Originally posted by Austin Hunter:
You the man. I started my 380 gr SS in my 404 at 2,400 (tried some loads up to 2,800) and thought I was ok. Well. 2,300 felt even better and might try 2,250. A 380 gr SS at 2,525 is a KILLER and has some real range to it - legit 300 yard round.

BTW - did you try H4350? That's what Northfork recommended. I'd like to try Varget at some point.

H4350 is indeed great in the tighter .423-groove barrels on 404 Jeffery rifles.
Not so great in my McGowen .4245-groove barrels.
Varget is tops there.

But I do use large amounts of H4350 in the 404 RIP (.423/.416 Rigby Improved Plus).
112 grains of H4350 will make the 320-grain GSC HV go 2900 fps in a 23"-long McGowen barrel.
No case capacity limitation there.

I like your graph!