I saw a thread some time ago about this (Simple rebarrel and ready to go) feasibility. I can't seem to find that thread. It seemed some said yes and some said no. The conversion was/was not simple. I am thinking of such a project. Anybody done it? Thanks D

Long post by RIP in Big Bore forum at the moment.

Not simple but economically done. Mine started life as a .300RUM. If you don't want all of the bells & whistles, you could get it done w/ a new barrel, sights (if you want irons) & a bit of feeding work, maybe, & away you go.



If you use a different caliber to start, more work is likely, magazine, feed rails, follower, bolt face, ejector.

D Hunter,

I havent done it yet, but in the process, got the mdl 70, got the barrel on order, got wood for stock. My gunsmith says its no big deal.

Fred,
How many down can you get, 2 or 3?

I have always used a drop box on mine and of course that required a new stock which will run the cost up considerably for the most part, but not with me because I am a stock maker...

fredj338,

I may have asked this in the past but I've slept since then, is that a Dakota rib.

How to know if your Gunsmith is really top notch? If he can get a standard Mauser or M 70 to feed with standard factory ammo!!!! On my H&H .404 built on a post war F.N. mauser action, the magazine box is considerably wider than that of a 9,3, .375 or .458. My Cogwell & Harrison feeds OK but is a bitch to load in a hurry. Most Cogswells I've handeled don't work properly - feeding trouble

Also- Most of the reamers from ammerican sources we see out here produce a chamber that doesn't work with RWS factory ammo. Most "custom" .404's out here will only work with reloads. I LOVE the .404 but hokoyo, basop- beware !

Ray, it will hold (3) down. I would like to have a Blackburn bottom metal, but you're right, it adds quite a bit to the cost for a new stock, maybe later.

Gringo, it is a modified Dakota rib, NECG front.

Ganyana, you are right, Clymer made the reamer that was used & since I can't get factory ammo here, it is really a mute point. I load Norma brass using Redding dies. Feed, function & accuracy is all I could ask for in a DG / heavy plainsgame rifle.

Fred,
Three down and one up the tube should be plenty 99.9% of the time, and you could say that same if it held 10 down! poop happens!

I think I like the drop box because I just like that look! and who knows maybe some day that extra round may help if the PHs gun jams, and the other guns in the party jam and the Buff is right on top of us and if all those other guys are married men with family and decide to sceedaddle and leave old Ray to his own devices.. , ain't likly pilgrim!

Point being your in fine shape with a great 404...

Yes,

I too have proven the 300 RUM box of a Winchester SS Classic M-70 is perfect as is, just needs the bolt face opened up to 0.545". Box holds 3 down, plus 1 in chamber.



My reamer was a Dave Manson. Dave is smart enough to cut the reamer to CIP specs for the 10.75x73 Mauser and call it the 404 Jeffery. No worries with factory ammo, if the factory ammo is any good.



I also have a CZ 550 Magnum in 375 RUM, that has given me fits to get feeding smoothly. Now it does, but it holds only 4 down, of 375 RUM, with a little room to spare.



I just tried the 404 Jeffery dummies in it, and LO AND BEHOLD!!! It easily holds 5 of those goose-necked 404 Jeffery cartridges, and feeds slicker than owl crap.



I shall join Ray A in the high cotton, with a CZ 550 Magnum in 404 Jeffery. It is a six shooter with no difficulty, five down and one up.



And just to show that I am educable, I shall now concede that the 404 Jeffery's Rimless Nitro Express of 1905, was the first and the best true bolt action dangerous game rifle cartridge. There never has been nor will there ever be anything better. The rest are just pretenders, yes even the 416 Rigby.



404 Jeffery is King, long live the King.



Now if there was only a good .423 caliber sheep bullet available, I could finally rest easy.



Maybe JohnCharlieNoak, Ray's unacknowledged illegitimate son, who is yet well connected to a CNC lathe operator, despite his heritage, may come up with a substitute for the GSC 320 grain HV and a 400 grain banded FN, dedicated solely to the .423 bore. I won't hold my breath, however I will cross my fingers.

Strange but all of my few post are about the 404 in one or another way. My 404 jeffery is built on a brno zkk 602 action with a walther barrel and yes it holds five down and one in the camber.Made a new mag box after old oberndorf measurement and it feeds like a greased pig.

My .404 being built on a 1909 Argentine will have 3 down and one up the spout, I want this rifle to be sleek and reasonably light.

So would a CZ 550 be a better starting platform? If so what would you start with, a 375 or a 416 in CZ. Thanks "D"

The bolt face is too big on a .416 Rigby. Need to go with the .375 H&H, unless you are going to get a new bolt. It is tough to add metal to a bolt face.



The CZ box that holds 5 of the 404 Jeffery cartridges is a standard CZ .375 H&H, and it has the faint vertical ribs stamped in the side of the box.



Mine is an AHR action that has a left receiver wall that is blank of the CZ logo roll stamping. Otherwise it is the same as the standard CZ 550 Magnum in .375 H&H. However it has been pillar bedded in a custom walnut stock, but I don't think the pillars have caused the magazine to be any deepr.



Both the CZ 550 Magnum and the M70 RUM have their forte, and would be easier to do than a worked over Mauser, the highest art form.

RIP,
SAINTS PRESERVE US! you have seen the light, you have been born again, you are a good son after all, but still illagitamate..

Sooo...... Let me get this straight. We can do a Jeffrey on either a model 70 or a 375 CZ with only rebarrel, open the bolt face and maybe a little feeding /ramp work? Restocking with either is reccomended but not a necessity. Mod 70 you will get a thinner stock but only 3 down. With the CZ it will take 5 down, as is? How about leaving the boltface as is in the ultra mag and just using 375 ultra mag brass and 404 dies? Would that work? That would make it a 404 ultra mag wildcat I guess. The brass for that would be a fair amount cheaper than the Jeffrey stuff. Custom headstamping for african ventures. If the boltface is altered to Jeffrey dimensions will the Ultramag brass still work? Looks like it might have too much play in it but I don't know. Answers ? Thanks "D"

D Hunter,
There is an old saying in the photography world to the effect that the cheapest part of the process is the film, so buy the best, and buy a lot of it.
I think the analogy holds true in the big bore world. Add up the cost of 100 Norma or RWS 404 Jeffrey cases. Then add up the cost of the rifle, the conversion work, the bullets, the air fare to the hunting fields, the daily guide fees, the trophy fees, etc., etc. Divide the second sum into the first number and the cost of brass will likely be only a few percent of the total.
Loaded to modest pressures these big bore cases last a very long time.
I have arrived at a hunting destination and had my guns make it, but not my piece of luggage with the ammunition.
In Africa it would be somewhat easier to locate a handful of 404 Jeffrey or its metric equivalent than to find RUM brass of any caliber.
As to the boltface, it would likely feed and fire ok, it is the extraction and ejection that I would be most concerned about. For any hunting rifle I demand smooth feeding, a bang every time I pull the trigger on a live round, dead nuts reliable extraction, and right smart ejection. I personally wouldn't willingly carry a rifle in which I felt any of those functions might be compromised.
My two cents is that you go with either a Winnie or Che Zed action, Have someone like John Ricks, Mark Penrod, or Dennis Olsen do the metal work, have my dad whittle you a stock, and go hunting.
JCN

D Hunter, I have made some .404s from .375RUM cases & they fire, feed & function fine. For practice rounds this would be an economical way to go, but it is abit of work. The Norma stuff isn't that expensive, just put aside 60 or so for hunting across the pond & not worry about.
The CZ is a very good way to go, especially in the American version. You get the drop mag. & stock but you'll have to add the M70 safety (me anyway). Both need new sights, you'll come out a bit cheaper if you want 4-5 down on the CZ American. Keep us current on the project.

404 Jeffery brass is available from Mast Technology. It's B.E.L.L. brass.

I assume the first half of my post is on target? "D"

D Hunter,
Yes you are on target, but you didn't specify an M70 that is already set up for the RUM line of cartridge. It seems to have slight but important differences in the box, follower, rails, etc. versus the standard .375 H&H setup. I have not bothered to measure everything with calipers, but it seems that if the 300 RUM works, then the 404 Jeffery surely will.

The CZ box is slightly over an inch wide at the back of the box, and it seems ideal for the 404 Jeffery.

Some inside the box measurements:

M70 RUM box:
width at rear of box = 0.975"
width at front of box = 0.740"
length of box = 3.620"

CZ 550 Magnum box
width at rear of box = 1.057"
width at front of box = 0.840"
length of box = 3.855"

The M70 SC 300 RUM box that I measured does have windows cut in the top of the box on each side. These windows are 2.270" horizontally and 0.440" vertically, about centered on the top edge of the side walls of the box, or maybe a little forward of centered.

Pick a M70 Ultra for conversion if it will primarily be a sheep hunting rifle.
Go with the Che Zed if you are after a DGR.
JCN

I've used quite a bit of that B.E.L.L. .404 brass and am not happy with it at all. It tends to be soft in the base, primers start out less than tight and get loose quickly, and NOT due to high preasure loads. On top of that, it isn't much cheaper than Norma, which is a lot better.