New owner of 470 n.e.

[Rare Breed]

Which diameter would use in the 470?

3/8

 

[Rare Breed]

I have been shooting my Chapuis 470 for the last couple weeks working on loads and consistency. I leave tomorrow for the Dark Continent and an appointment with a Cape buffalo.
Mine seems to digest almost everything I throw at it well. Both barrels stay inside of 3 1/2" at 50 yds with several different loads and bullets, if I do my part.
I have settled on 500gr TSX's pushed by 82.5 gr of Reloader 15.5 and a Trader Keith foam wad. Again, if I do my part, they will regulate at less than an inch with them often touching. Speed is right at 2075fps.
I am also taking a few CEB solids pushed by 83gr of 15.5 that groups close enough to give me no worries.
4831 and 4831SC shot very well too, with slightly more speed, but much more recoil due to the increased amount of powder.
Good luck and enjoy a fine rifle.

P.S. JJ Perodoux recommended 79gr of 3031 for a starting point as well.
And as always, start low and work your way up. What is safe for me, may not work for you.

80 grains IMR3031 sweet spou

 

[Racer00]

Rare Breed, I believe 3/8 would be too small for a 470 NE. 3/8=0.375. I would think 1/2” would be appropriate.
Please correct me if I’m wrong. I use Trader Keith’s Kynoch foams. I believe they are the #2

 

[Riflecrank]

Rare breed surely typo-ed.
5/8" diameter backer rod is good for .470 NE too.
1/2" is perfect in .458 caliber cartridges.
The caulk-backer rod has replaced Dacron fluff for me too.

109.0 grains of H4831 SC
F-215 primer
Federal nickel-plated brass case 470 NE
No filler

Way back when ...
In my Merkel .470 NE (23.6"/600mm barrels)
that load gave these velocities with both barrels impacting
right near the bullseye at 50 yards, within an inch all around the center and not crossing,
with the following bullets:

500-gr TBSS (Original Jack Carter): 2138 fps ave with 15 fps ES for four shots (RLRL)

500-gr Woodleigh Weldcore RNSN: 2153 fps ave with 22 fps ES for four shots (RLRL)

500-gr GSC FN monometal copper: 2116 fps ave with 34 fps ES for four shots (RLRL)

A fun load for plinking, accurate but crossing at 50 yards to about one inch on either side of the bullseye, elevation right on:

92.0 grains of RL-15
F-215
Norma brass case 470 NE
Foam wad filler

400-gr Hornady JHP (a .475 Linebaugh/480 Ruger handgun bullet): 2203 fps ave
26 fps ES for four shots (RLRL)

I dissected Federal factory loads
(TBSS and Woodleigh 500-grainers)
and found them to be using ~87 grains of a powder that looked like RL-15 and NO FILLER !!!

I was told through the grapevine that those cartridges were primed with "F-216" primers,
unavailable to handloaders,
way back when I was doing this stuff, in 2002,
hot off of my first African trip, to Botswana in 2001,
with the poor man's battery of .375 H&H and .416 Rigby bolt actions, which served very well.

 

[Riflecrank]

Excerpt for book review purposes:

Book review: Excellent book.

 

[Riflecrank]

Though the data from Graeme Wright is from five different rifles, not specified which is which except by barrel lengths,
it is well known that use of a foam filler wad will allow use of less powder to achieve same pressure/velocity and greater uniformity.

94.0 grains of H4350 with foam wad filler seems to be the champ
(highest MV, least recoil)
for getting 2110 fps in a 23.5" barrel
500-gr Woodleigh Weldcore RNSN
with BELL case and F-215 primer,
according to the table above.
2700 bar = about 39,150 psi

 

[MacJenkins]

Here I am loading 450 right now for my trip coming up. 1/2” backer rod on the left and 5/8 right. This is from Home Depot.

1/2” is is perfect for 450, ever so slightly loose for 470 but I still use it as my 5/8” is a bitch to get in 470. Need to maybe find a different brand as I would like it a smidge tighter for 470 but it’s been fine for over a 1000 rounds through my 470 the past 17 years.

3/8” goes in my 375 flanged and 400/360 Purdey.

1/2” for my 450/400’s, 450 and 470

5/8” for my 500’s and one 577. And also a friends 600 it fits great.

Been meaning to snag some 1/2 from Lowe’s to see if it would be a bit tighter in the 470.

 

[Riflecrank]

The old rule of thumb was that Cordite charge weight = same weight of IMR-3031 used with a filler.
75 grains with 500-gr bullet for 470 NE, probably old school slow so work up to what gets you to bullseye.
I might try that same thing with HODGDON BENCHMARK.
For RL-15 charges I would substitute VARGET.
The 470 Mbogo of Dave Estergaard (.475/.416 Rigby Improved) has about identical case capacity as
the 470 NE.
It is a good bolt-action test bed for 470 NE loads, to save wear and tear on your DR.
So too a Ruger No. 1 in 470 NE.

 

[Rare Breed]

Rare Breed, I believe 3/8 would be too small for a 470 NE. 3/8=0.375. I would think 1/2” would be appropriate.
Please correct me if I’m wrong. I use Trader Keith’s Kynoch foams. I believe they are the #2

You are absolutely correct with #2 Trader Keith. I have not been able to buy any more from them. I still see their website up but can never get them

 

[Riflecrank]

Using 470 NE Norma bare-brass or Federal nickel-plated cases,
(case capacities about identical:
Norma = 150.5 grains gross water
Federal = 150.3 grains water gross)
and F-215 primer,
this would be an interesting experiment for 470 NE:

75 gr BENCHMARK/IMR-3031 with filler
85 gr VARGET/RL-15 with filler
95 grains of H4350 with and without filler
105 grains of H4831 or H4831 SC without filler and with ~1/4"-tall foam wad crammed in

Faster powder, higher peak chamber pressure, less recoil.
Slower powder, lower peak chamber pressure, more recoil.
All would be pretty close to same MV.

Whatever gave the smallest extreme spread or least standard deviation for four shots, RLRL,
might be the easiest to see where the rifle was shooting with that load,
for further tuning to "parallel to infinity" and sight adjustments.

The 470 NE is one of those universally approved cartridges that is both SAAMI and CIP homologated.
SAAMI allows it a higher MAP of 41,000 psi. CIP allows 2700 bar (~39,150).
Both chambers have essentially no throat, the base of the leade at start of their leade-only throats is 0.4764" diameter for bullet to enter from the case.
SAAMI leade hemi-angle = 1*30' 00"
CIP leade hemi-angle = 0*50'01"
So CIP chamber will give slightly lesser pressure and velocity with the same ammo as the SAAMI chamber.
Same ammo would probably give 41,000 psi in a SAAMI chamber and 2700 bar in a CIP chamber,
or at least tend in that direction.

Alas, the 470 Mbogo of Dave Estergaard has a whopping modern throat that is 0.4760" in diameter and a parallel-sided free-bore of 0.4000" length followed by a 1*30'00" leade hemi-angle.
It will be about 50 fps slower in MV for same barrel length as a 470 NE with same propellant and bullet.
Quality Cartridge 470 Mbogo brass has a gross water capacity of 150.8 grains,
only a fraction of a grain difference from above 470 NE brass cases, negligible in effect.
Still could be a useful "load mule" for trying 470 NE loads.
2100 fps MV would be the goal, with same powder and fillers used in 470 NE.
Not the usual 2500 to 2700 fps MV with 500-grainers for the 470 Mbogo wildcat loads.
Whatever the pressures of the 470 Mbogo, they are certainly more comfortable than the much
prevaricated-about .475 A&M.

Antique rifles especially might be regulated for 2000 to 2050 fps, even with longer barrels.
Read Graeme Wright on that, pressure standards changed.
Modern rifles might like the 2100 to 2150 range of MV better, even with their shorter barrels.

One thing great about the 470 NE throat is that QuickLOAD is quite good for predictions of its no-filler loads (H4831 & H4350).
Default powder specs are not reliable with longer throats or fillers.