.375 to .423 is a bit more then a slight jump. The barrel would be rebored. They basically just (in simple fast terms here, not scientific) drill a bigger hole, then re-cut the rifle lands. Think of a block of wood, drill a 1/2" hole in it. Now put a 3/4" bit in the chuck and drill through the same hole. Voila!

Not sure where this has gone. I lost my wild catting abilities a few years ago, and am just getting back into reloading again in the next 6 months. Very likely, I'll be revisiting this thread then

one has several choices
new barrel
rebore 375 barrel
new build

Mr Echols was going to make one for a client. He was saying the 2.8" length would be best. Last I spoke with him he said he was working on the reamer issue. He was saying its hard to determine the exact juncture where the neck start and the taper ends. The reamer guy he uses was talking about some difficulty making a one piece because of the extreme slight angles. I'm not a reamer expert but I was thinking a neck throater would work on a removable pilot. Need to measure the neck dimensions of a variety of brass. I'll call him and do a follow up to see if he finished it.

Bummer about the reamer! I guess everything else WAS a bit too easy lol

I think a two piece should be ok.

quote:

Originally posted by boom stick:
Mr Echols was going to make one for a client. He was saying the 2.8" length would be best. Last I spoke with him he said he was working on the reamer issue. He was saying its hard to determine the exact juncture where the neck start and the taper ends. The reamer guy he uses was talking about some difficulty making a one piece because of the extreme slight angles. I'm not a reamer expert but I was thinking a neck throater would work on a removable pilot. Need to measure the neck dimensions of a variety of brass. I'll call him and do a follow up to see if he finished it.

This obviously can’t be taken as gospel…but hopefully it just might put you in the “ball park”.

Here’s the CIP minimum chamber specification data for the .375 H&H Magnum extracted from QuickDESIGN:
Length to Shoulder: 2.4165” (61.38mm)
Length to Shoulder-Neck Intersection: 2.4976” (63.44mm)
Length to Neck Chamfer: 2.8701” (72.90mm)
Shoulder Diameter: 0.4484” (11.389mm)
Diameter at Shoulder-Neck Intersection: 0.4051” (10.29mm)
Diameter at Neck Chamfer: 0.4039” (10.26mm)
Bullet Diameter: 0.375 (9.525mm)
Difference between Bullet Diameter and Neck Chamfer: 0.0289” (0.735mm)
Difference between the “Length to Shoulder” and the “Length to Neck Chamber”: 0.4335” (11.01mm)

Then to build your .404/.375 H&H Magnum cartridge… I averaged the CIP minimum chamber specification data for the following four cartridges at the case mouth dimension:
.375 H&H Magnum
.416 Remington Magnum
.416 Ruger
.4041 Jeffery
And came up with an average of 0.031475” (difference between chamber dimension and bullet dimension) – so why not just call it 0.031” for the sake of this endeavor…

And using the modern 0.423” bullet diameter plus the 0.031” gives:
Bullet Diameter: 0.423 (10.744mm)
Diameter at Neck Chamfer: 0.454” (11.53mm)
And obviously the dimension at the Neck Chamfer has just obliterated the .375 H&Hs shoulder diameter which means that it’s a clean sheet.

So for your finish reamer…there are two choices for your .404/.375 H&H Magnum – 2.80” case length:
1st Option = Straight taper length to Neck Chafer:
Length to Neck Chamfer: 2.800” (71.12mm)
Diameter at Neck Chamfer: 0.454” (11.53mm)
Have your finish reamer manufacturer compute the data necessary to accommodate 0.800” for your bullet options and you’re ready to go.

2nd Option = Ghost Shoulder Case:
For this option I utilized the Difference between the “Length to Shoulder” and the “Length to Neck Chamber” for the .375 H&H Magnum for the new case neck length…so here goes…
Length to Neck Chamfer: 2.800” (71.12mm)
Length of Case Neck: 0.4335” (11.01mm)
Length to Case Body-Neck Intersection: 2.3665” (60.109mm)
Diameter at Shoulder-Neck Intersection: 0.455” (11.557mm)
Diameter at Neck Chamfer: 0.454” (11.53mm)
You’ll notice that I added 0.001” at the Case Body-Neck Intersection for ease of extraction with high pressure loadings.
Again…Have your finish reamer manufacturer compute the data necessary to accommodate 0.800” for your bullet options and you’re ready to go.

Hope this provides some information of use.

No reason a reamer manufacturer can't make either style finish reamer - just be sure and specify removable pilot!

Merry Christmas Capo
Thanks for all that great info.
I think I will just have to make a bunch of dummies from a variety of brass and measure them to confirm.
Nothing we can't get done together
What Tiny Tim said.

quote:

Originally posted by boom stick:
Merry Christmas Capo
Thanks for all that great info.
I think I will just have to make a bunch of dummies from a variety of brass and measure them to confirm.
Nothing we can't get done together
What Tiny Tim said.

Merry Christmas Boomy,
Very good idea to measure up some brass at the neck as there will be both thick and thin... If you can might be a good idea to expand them out and seat a .423 caliber bullet in them to get a true OD measurement at the neck area...

Measuring loaded 375 HH should give us an accurate measure within 1 or 2 thou. The brass won't thin that much necking up but will shorten.

I'd say the average neck OD would be about .450" add 7 thou for a generous DG feeding finish reamer giving a .457" diameter and measuring fired cases and maybe a chamber cast to get the exact spot of transition from a 375 chamber that has had a .457" neck/throater run in.

Talked to Dave Manson.
He liked the idea of the wildcat and said making reamers would not be an issue. He said both removeable and solid reamers would work but said the cost was similar so might as well go one piece.

quote:

Originally posted by boom stick:
Talked to Dave Manson.
He liked the idea of the wildcat and said making reamers would not be an issue. He said both removeable and solid reamers would work but said the cost was similar so might as well go one piece.

Boomy,

I recommend that you reconsider going with a removable pilot reamer as it will allow the gunsmith to use a pilot that very closely matches the actual bore diameter of the barrel. I think of all the calibers out there, this is likely most critical with the barrels used for the .404s due to the differing bore and groove diameters combinations used in barrels of this caliber.

Anyway, just something to consider.

The good lady wife just bought her daddy's stainless Weatherby .375H&H for my big five-oh birthday gift. I think I just might know what it needs doing to it in the future!

Btw, it pays to marry well

BwannaCole
Good for you on marrying well
Would be cool to have you make one.
Capo, well either can be done. Let's try both

Any progress on the 404-375 H&H?

Look how nice and easy it is to fit a .395 H&H into a Pre-64 M70:

http://forums.accuratereloadin...651033651#4651033651

Of course the standard bullet diameter of the 404 will have great appeal,
but I am stuck on .395 so I have bullets!

Five-Shooter and perfect feeder with 330-grain FN solid COL of 3.570" and 310-grain Hollowpoint semi-spitzer soft COL of 3.599".
Also a 410-grain Gas-checked LFN cast bullet:

Just need the extra chicken scratch to order custom reamers and dies.
I'll go with Dave Manson for the reamers. I don't have a 375 donor gun but I would not want dies and reamers to stop someone from building one if they wanted.

boom stick any new developments with the 404-375?I have had a donor for a while now and I would be interested in building one of these this year if there are dies and reamers available.

I'm not really into wildcats but this one seems easy and practical.I bought the donor to build a Lott but decided I didn't really want that much recoil.Just want a step up from my 375H&H.

Welcome to the forum.
D'Arcy Echols made the first one for a client. Maybe contact him for the reamer or the chambering of the barrel. He seems to be pleased with it. I hope you do make one since it is one of the best big bore wildcats I think that exist. If he is too busy with other work maybe we can help get you up and running. Let me know what input you need or questions you have after talking with D'Arcy.
http://www.echolsrifles.com/

Boomy,

I posted on the other thread a recommendation that perhaps you and DArcy could settle on a chamber specification - or perhaps two if both 2.8" and 2.85" cartridge lengths are desirable... Maybe even a 3rd for 3.4" magazines - then release the specs here on AR for all to use.

As an FYI, I'm using a 0.220" Freebore including chamfer height for my .423/338 Lapua Magnum which is more than sufficient with monometal bullets from Barnes, CEB, and NF.

RIP, really interested to see these pics especially the second one of the feed ramp. Has this been altered to suit a longer loaded cartridge? It looks like a sharp edge on the front of the feed ramp and lower locking lug recess? What are those dot marks on the left side of the feed ramp.

My Type A Oberndorf Mauser, a standard 98 action, has been opened up for the 404J cartridge and it too has a sharp edge to the feed ramp, looks identical to the 2nd pic you show. This ramp/lug recess has never shown any sign of wear on my Mauser with the bolt locking up good and tight. I have shot plenty of full power factory loads in the 404 but in deference to the opened up action I would hesitate to to push loads up around the 2,400-2,500 fps level that some do in the 404.

quote:

Originally posted by capoward:
Boomy,

I posted on the other thread a recommendation that perhaps you and DArcy could settle on a chamber specification - or perhaps two if both 2.8" and 2.85" cartridge lengths are desirable... Maybe even a 3rd for 3.4" magazines - then release the specs here on AR for all to use.

As an FYI, I'm using a 0.220" Freebore including chamfer height for my .423/338 Lapua Magnum which is more than sufficient with monometal bullets from Barnes, CEB, and NF.

The 404 Jeffery with its 2.85" case fits in a military Mauser because of shorter projection bullets. If the shorter CIP spec bullets are loaded out to .8" would there need to be more freebore than .2"?
D'Arcy wanted a 2.8" case for feeding purposes if I remember correct and to use 458 Lott brass. With 2.85" cases and 404 CIP spec bullet protrusion working in a military Mauser I don't see why not to go 2.85". To be a true 404-375 HH it Would have to be 2.85" case length. Obviously fire formed 375 brass would be a tad shorter but still work fine loaded to the same length. What really matters is the feeding, using the same OAL for specific loads. I see more potential problems with a shorter chamber than a 2.85" chamber. The confusion will be with CIP protrusion and .8" protrusion. My liking is a one piece reamer to 2.85".

Reference the 500 AR Nyati thread regarding needed freebore to accommodate factory C&C construction bullets. Monometal construction bullets can be another issue but as I've measured my 380gr .423 caliber NF FPS as well as the four weight .423 caliber CEB BBW#13 HP NonCon and FN Solid bullets - no problems with the 0.220" specification.

Don't forget that you need to determine a "trim to length specification", the "maximum case length specification", as well as the "chamber length specification". And the difference between the "trim to" and the "chamber length" specification adds additional length before the bullet engages the rifling.

What is the average length of unfired formed factory .375 H&H brass? How much does this unfired brass shorten when it is run into a .375-.423 neck expansion die? Does the brass shorten further or lengthen slightly when first run into your .404-375 FLR die? Is this FLR length shorter than your "trim to" specification or is it between your "trim to length" and " max case length" specifications? How much is the neck wall thickness reduced by this process?

And finally, happens to the case length and neck wall thickness if RIP's CRF fire-forming process is used with cheap C&C .375 caliber bullets and new unfired .375 H&H brass?

Oops…I forgot one. How are your dimensions affected – especially the neck thickness dimensions – by using Belted Basic Brass run into your FLR die to form you .404-375 H&H cases?

aww, tut tut tut -- are you hijacking this thread on 404 with your .395? recall how you feigned a slight, and we were talking the same caliber bullet? careful how you call people out, doc

quote:

Originally posted by RIP:
Any progress on the 404-375 H&H?

Look how nice and easy it is to fit a .395 H&H into a Pre-64 M70:

http://forums.accuratereloadin...651033651#4651033651

Of course the standard bullet diameter of the 404 will have great appeal,
but I am stuck on .395 so I have bullets!

Five-Shooter and perfect feeder with 330-grain FN solid COL of 3.570" and 310-grain Hollowpoint semi-spitzer soft of 5.599".
Also a 410-grain Gas-checked LFN cast bullet:

I settled on 2.830 as the new Remington cases I expanded to .423 measured approx. 2.820-2.826 for an OAL. I plan to trim them all to a standard length for crimping purposes and this seemed to be a happy medium with this brass and the canalure position for the bullets I want to use. Crimped I want the bullets to have an OAL of 3.600 max when loaded to fit into the Pre-64 300 H&H magazine box. As I stated before my reamer is a neck and throating reamer only with an adjustable stop collar so I can adjust the OAL of the chamber if desired.

That's very good information..."expansion average of 2.820"-2.826" OAL"... Thank you!

I think that if others interested in this wildcat that had the dies to form some virgin cases from a variety of manufactures one could establish an average OAL length to start with. It has been quite some time since I've had any Basic belted magnum cases that measured anywhere near 2.830 to 2.850 out of the bag.

quote:

I think that if others interested in this wildcat that had the dies to form some virgin cases from a variety of manufactures one could establish an average OAL length to start with.

This is a very good recommendation and definitely go a long way to establishing some benchmarks.

Unfortunately the only belted brass that I possess is a few 264 WinMag and a few 270 Weatherby Magnum so I’m of no help to this cause…

I posted this on the 375 H&H necked up to .423 thread, Big Bore Forum:
http://forums.accuratereloadin...381072002#8381072002
I thought it should be posted here to resurrect the discussion…

quote:

I haven’t seen much discussion on this topic since the Echols thread so decided last night to do some computing today.

I figured the following data points were those required to clean up a .375 H&H Magnum chamber as well as accommodate Con’s Winchester brass neck wall thickness of 0.012” (0.024” sized up for .423 caliber; the 1st Data Point – 0.452” @ 2.416” (chamber shoulder location) and the 2nd Data Point – 0.451” @ 2.870” (case mouth at chamfer). So I played with my Visio drawing program and QuickDESIGN and came up with the following chamber drawing – it should clean up most .375 H&H Mag. chambers and will work just fine with a new barrel…

First the Chamber:


And the Cartridge:

Has there been any additional movement by anyone yet?

Jim,
The only movement I see was that jeffeosso was "moved" by my post above, even doubled the photo posting for me.
That was to illustrate how nicely the .423/.375 H&H fits into a Pre-64 M70 Winchester action that was originally a 300 H&H or 375 H&H.
Perfect feeder with no extra work.
A 4+1 five-shooter.
Sweet.
Too bad I only had a ".395/.375 H&H Unimproved" to illustrate the point.

Great drawings and info Capo. Thanks. D'Arcy made his 2.8" brass length FYI. I would like to see what the fire formed from 375 brass length would be.

According to the drawing the neck tension area length is just a dad longer than the bullet diameter .4334" compared to .423". The design lends well to compressed loads and cast bullets. The only thing wrong with this cart is that it was not made a hundred years ago.

quote:

Originally posted by boom stick:
Great drawings and info Capo. Thanks. D'Arcy made his 2.8" brass length FYI. I would like to see what the fire formed from 375 brass length would be.

Very true.

However Con's .375 H&H Winchester brass using a .423 Expander Die came out to approximately 2.830" length so only reason to trim shorter would be to match the shortest case length after expanding the neck.

Obviously using .458 Lott brass would result in cases longer than 2.85" as would using Hornady's .375 H&H Basic brass. I believe the .416 RemMag is also spec'd with a 2.85" case length.

I believe the .375 H&H Mag. based Winchester M70 and Remington M700 use a 3.650" internal magazine length though some may be a few 0.00X" shorter due to manufacturing variances. The CZ 550 Magnum action using a longer 3.8XX" magazine length. And the M98 Mauser based Zastava M70 is 3.60X" in length (though it can easily be opened to the same 3.650" length as the Win and Rem rifles.

So basically in modern rifles there's no reason to dictate the case length and COAL based upon the shorter 404 Jeffery/10.75x68 Mauser .423 caliber bullets. Just use the .375 H&H SAAMI 3.6" COAL, deduct you're spec. case length and that'll give you your maximum bullet nose protrusion for the 3.6" specification.

Regardless the chamber specs can easily be changed. I just used the same 2.850" case length & 2.870" chamber length (0.020" difference) that is SAAMI spec for the .375 H&H.

Anyway, ya'll decide. I'll redo the chamber and case specifications. We'll get it RIP certified and release it to the industry...

quote:

Originally posted by RIP:
Jim,
I only had a ".395/.375 H&H Unimproved" to illustrate the point.

...

Actually, Ron, you ripped loose a tirade for similar actions on my part. you, perhaps, don't call the incident clearly, which may be understandable.. though I do remind you that only hypocrites hold others to standards of which they are willing, themselves, to ignore.

quote:

The only thing wrong with this cart is that it was not made a hundred years ago.

Yes except it'd have killed the .375 H&H cartridge.

Oh yes, QD noted a 101.3grs water capacity.

Now it just needs to be paired with a smaller caliber cartridge - such as a .338/300 H&H Magnum.

Guess I need to check that one to determine if the .338 caliber would also eliminate the shoulder on the .300 H&H Magnum.

quote:

Originally posted by capoward:

quote:

Originally posted by boom stick:
Great drawings and info Capo. Thanks. D'Arcy made his 2.8" brass length FYI. I would like to see what the fire formed from 375 brass length would be.

Very true.

However Con's .375 H&H Winchester brass using a .423 Expander Die came out to approximately 2.830" length so only reason to trim shorter would be to match the shortest case length after expanding the neck.

Obviously using .458 Lott brass would result in cases longer than 2.85" as would using Hornady's .375 H&H Basic brass. I believe the .416 RemMag is also spec'd with a 2.85" case length.

I believe the .375 H&H Mag. based Winchester M70 and Remington M700 use a 3.650" internal magazine length though some may be a few 0.00X" shorter due to manufacturing variances. The CZ 550 Magnum action using a longer 3.8XX" magazine length. And the M98 Mauser based Zastava M70 is 3.60X" in length (though it can easily be opened to the same 3.650" length as the Win and Rem rifles.

So basically in modern rifles there's no reason to dictate the case length and COAL based upon the shorter 404 Jeffery/10.75x68 Mauser .423 caliber bullets. Just use the .375 H&H SAAMI 3.6" COAL, deduct you're spec. case length and that'll give you your maximum bullet nose protrusion for the 3.6" specification.

Regardless the chamber specs can easily be changed. I just used the same 2.850" case length & 2.870" chamber length (0.020" difference) that is SAAMI spec for the .375 H&H.

Anyway, ya'll decide. I'll redo the chamber and case specifications. We'll get it RIP certified and release it to the industry...

Thanks Capo. I liked the 2.85" case length and yes oal can be played with out to 3.6" but talking to D'Arcy he explained better than I can remember that 2.8" cases feed better when crimped to canalure and maybe he can expound here. I like the idea of a tad longer chamber to accommodate most methods of forming the cases. I assume most will neck up or fire form 375 HH cases. This is a wildcat so as long as you stick to proper reloading guidelines you will be fine. I think it will be a while before SAAMI gets involved
I do like the RIP cert though
El Jeffe made me an expander on his lathe and I still have the first necked up cases thanks to him.

quote:

Originally posted by capoward:

quote:

The only thing wrong with this cart is that it was not made a hundred years ago.

Yes except it'd have killed the .375 H&H cartridge.

Oh yes, QD noted a 101.3grs water capacity.

Now it just needs to be paired with a smaller caliber cartridge - such as a .338/300 H&H Magnum.

Guess I need to check that one to determine if the .338 caliber would also eliminate the shoulder on the .300 H&H Magnum.

The .410" will clean up the shoulder. I checked a few years ago. Similar to the ultra rare 40 Eley but longer.

quote:

The .410" will clean up the shoulder. I checked a few years ago. Similar to the ultra rare 40 Eley but longer.

Yep, tried the .338 and it created a really old style cartridge with a 0.471” long neck with 8º shoulder angle - but it still has a shoulder...

quote:

Originally posted by DArcy_Echols_Co:
I think that if others interested in this wildcat that had the dies to form some virgin cases from a variety of manufactures one could establish an average OAL length to start with. It has been quite some time since I've had any Basic belted magnum cases that measured anywhere near 2.830 to 2.850 out of the bag.

Here is one example:



Hornady basic cylindrical .375 H&H brass averages 2.868" of 5 checked.

Sized to .375 H&H, in Hornady .375 H&H dies, it grows to about 2.935" length.

Necked up in steps (.395, .411, and finally a 404 Jeffery expander ball), it shortened to 2.908".
I skipped right over the .416 expander which I could have also used.

No annealing was done.
It was not trimmed.
It is not perfect.

A Woodleigh 400-grain RN FMJ "solid" was seated and crimped in the 2.908" brass.
C.O.L. as shown above is 3.570".
Neck O.D. is 0.444", near case mouth, just before the crimp.
Maybe 0.445" near base of bullet, O.D. neck brass.
The steel FMJ Woodleigh 400-grain RN "solid" diameter is 0.422", by my check with caliper.

The Hornady basic cylindrical brass neck wall thickness at case mouth by caliper was about 0.012".
Could have been 0.011" with a rough edge.

The original case length of 2.850" for the .375 H&H is certainly good with use of the Hornady basic brass
for making the 404/.375 H&H.

Jim's chamber minimums and brass maximums as drawn are perfect to handle any mass produced ammo and rifle combination,
when this wildcat takes off.
Riflecrank Internationale Permanente certified.

Lots of good info. Thanks RIP.
It seems all the wrinkles have been ironed out and ready for mass production

boom stick,

Your 404/.375 H&H cartridge will be really easy to load with basic brass and proper reloading dies.
Please disregard "warpage" in my dummy above.
I hastily "ripped one off" with make-do dies on hand here.