I've Applied For Membership Into the 404J Club

[Bonk]

I've been pondering this for a while now. I really want a 404J. I'm a sucker for old school calibers and the dream of a buffalo hunt isn't dead yet.

I have a couple of nice 375H&H rifles (Ruger RSM & an AHR upgraded CZ550) and I considered converting one of them to 404J but I think I'm just going to sell one or both of them. I also have 9.3x62 and 9.3x74R rifles that fill the medium bore niche in my collection so if I get a 404J I don't need 375H&H. That leaves my beloved AHR custom built CZ550 300H&H as a possible donor rifle and I think that's the direction I'm going to go. Before anyone hollers "Blasphemy!" let me explain.

First of all I have more than one 300H&H. Second, my CZ550 is a really big rifle for 300H&H. I'm not a weight weenie and I knew going in that a 300H&H built on a CZ550 magnum action and a walnut stock was going to be a monster for a 30 caliber rifle and it is. About 9.5 lbs loaded with a scope a sling. I still love the rifle but I've convinced myself it will make the perfect platform for a 404J. It already has the magnum receiver, heavy walnut stock, ebony fore end and all the other wonderful AHR goodness. All it needs is to be rebarreled and I think the bolt face has to be opened up a bit.

The idea of me getting a 404J of some sort has been decided. That will happen. The question was do I defile my 300H&H custom build to do it? The answer in my mind was yes. I really don't want to spend the kind of money it would take to build a 404J from the ground up plus I really think rebarrelling my 300H&H is the best move for the rifle. It's built like a 404J and it really isn't happy as a 300H&H.

I solidified my membership application by buying a couple of boxes of 400gr Hornady DGX Bonded .423 bullets yesterday. Matrix Gunsmithing is looking for a barrel and will do the work. I'm on the hunt for dies and brass. Wish me luck.

BTW, does anybody need any .411 bullets? I have 4 new unopened 50rd boxes of Hornady Interlock 405 Win 300gr SP I bought about a year ago when I was considering 400H&H. I saw them in the dusty corner of a LGS and I bought them on the spot because I knew they were hard to come by.

This is the donor rifle:

 

[Captain Munro]

I think the 404 is one of the most interesting cartridges, and one that I would love to have. Of course I want rifles chambered in all the African cartridges.... Looks like a hell of a donor rifle too.

 

[baxterb]

You will need a lot more than a rebarrel and bolt face to go from a 300H&H to 404. The 404 has one of the widest mag boxes out there. And that will have to be done correctly in order to get the thing to feed. Depending on the dimensions of your stock, you may not have enough room to open the belly to accept the much wider 404 box. The action and feed rails will also need to be altered to accommodate a new mag box.

 

[sierraone]

Your .375 RSM will convert with a new barrel. I know because I have one. I don't know about a .300 HH converting though.

 

[K E Johnson]

I am having mine built on a Winchester 70 originally chambered in 300 Remington Ultra Mag to get around the feeding issues hopefully.
I can’t remember who had the dies in stock, but managed to pick up a set after some searching.
Huntington Die Specialies had Bertram brass. I am still looking for brass myself. No emergency as rifle won’t be done for 6 months or so.
Best of luck on your build!

 

[Bonk]

You will need a lot more than a rebarrel and bolt face to go from a 300H&H to 404. The 404 has one of the widest mag boxes out there. And that will have to be done correctly in order to get the thing to feed. Depending on the dimensions of your stock, you may not have enough room to open the belly to accept the much wider 404 box. The action and feed rails will also need to be altered to accommodate a new mag box.

It's built on a CZ550 Magnum receiver. It's the same receiver and magazine all big bore caliber CZ550s are built on. In fact I just went and loaded the magazine with 5 458Win rounds just to check. No problem at all.

 

[Bonk]

I am having mine built on a Winchester 70 originally chambered in 300 Remington Ultra Mag to get around the feeding issues hopefully.
I can’t remember who had the dies in stock, but managed to pick up a set after some searching.
Huntington Die Specialies had Bertram brass. I am still looking for brass myself. No emergency as rifle won’t be done for 6 months or so.
Best of luck on your build!

Good luck with yours too. Love to see the finished project.

I'm in the same boat as far as components and dies go. I know it's going to be a long and patient stalk to find them but that's part of the fun and I won't be scheduling any buffalo hunts until I have everything ready to go. ;-)

 

[baxterb]

It's built on a CZ550 Magnum receiver. It's the same receiver and magazine all big bore caliber CZ550s are built on. In fact I just went and loaded the magazine with 5 458Win rounds just to check. No problem at all.

Not to be argumentative, but just because rounds will fit the magazine doesn't mean the max box dimensions are proper for the cartridge for optimal feeding. They should follow 'mauser's rule' of mag box geometry. When Mauser sold just commercial actions, they made about 27 different dimensional configurations - each specific to the cartridge, The 404 - with its length and big shoulder needs a very wide box at the front.

These are mag boxes from Darcy Echols. The third from the left is the 404. You can see how the sides are almost parallel - whereas the 458 Lott (1st) and 375 H&H (2nd) have much more taper.

When 404s are squeezed into a narrow box, the rounds will not stack right, but will be more vertical at the front. This will cause retention problems because the case is not under enough rail to keep it in place. (second pic)

Which results in this:

404 in G33/40

 

[nztimb]

This is an artical I have C&P from another forum so the authorship is by Tileyman of Australia

I originally wrote this article for our club magazine, pulled together from a few sources including Ludwig Olsen's Mauser Bolt Rifles and De Haas' Bolt Action Rifles... hope you find it useful!

Many thousands of Mauser 98’s have been rebarrelled to a multitude of modern cartridges very different to the original 7.92mm German military chambering.

While some of these conversions feed reliably from the magazine, many do not!

The fault often lies with the magazine and follower profile if it is left unaltered from the original layout.

Paul Mauser was a gifted firearms designer who carefully designed each magazine of his M98 rifles for a particular cartridge.

Box and follower dimensions were predicated on case dimensions... Paul figured that a staggered column would enable more cartridges to fit into a given magazine well than a single vertically stacked column.

In order to feed correctly from a staggered magazine, each cartridge needed support... from the magazine box on one side and a cartridge or the follower on the other side and underneath. With a stacking angle of 30 degrees, three stacked cartridges in contact would form the corners of an equilateral triangle:

By multiplying the Cosine of 30 degrees ((0.866) by the case head diameter, then adding the diameter to the product of the equation, the correct magazine box width could be determined.

For example, a 9.3x62mm case measures 11.95mm across the rim.
So 0.866 x 11.95 = 10.35 +11.95 = 22.3mm
Theoretically, that is the correct inside rear magazine box width for any cartridge deriving from the 9.3x62mm case.

However, all cartridges taper, and so must the magazine.

The same formula yields the proper box width at the point of shoulder contact:
The shoulder diameter is 11.45mm
So 0.866 x 11.45 = 9.92 + 11.45 = 21.4mm

A magazine box for a 9.3x62mm cartridge must therefore theoretically taper from 22.3mm to 21.4mm. Adding an extra 0.07mm ( 0.003") or so for dirty or oversized cases makes practical sense.
So a practical magazine box for the 9.3x62mm cartridge would taper from 22.4mm to 21.5mm

A magazine box designed for one cartridge works for others ONLY with the same identical front and rear diameters and the same span between them. Triangles between cartridge centrelines get steep when the box is too narrow, and rounds tend to cross-stack.

Paul Mauser also relieved the box sides slightly, from just ahead of the cartridge base to just behind the shoulder, so there would be no increase in friction between the case body and the box wall.

He lavished equal attention on the magazine follower, which on an original M98 mirrors the box taper.

The width of its lower shelf matches that of the case, with a 61 degree step between the upper and the lower shelf.

The top shelf is high enough to touch the next-to-last cartridge without lifting it off the last round in the stack (its half a diameter above the lower shelf at base and shoulder) The follower has a slope to follow case taper and keep the cartridges level in the box.

Side clearance of the follower to box is also critical.

Followers should be about 1.5mm (0.060") narrower than their boxes so they can wriggle a bit... especially important for the last cartridge.

A magazine follower for our 9.3x62mm example cartridge must therefore theoretically taper from 20.8mm to 19.9mm.
A magazine follower to fit the practical box above would taper from 20.9mm to 20.0mm

Floor plates that have been machined to hold the magazine spring tightly won't feed properly either... the springs are supposed to shimmy back and forth!

If the spring can't shuffle a bit as the bolt strips a round, it twists and the follower tips or ends up sideways... sometimes both!

Follower length is not as critical, but one that is too short will tend to 'dive' in the magazine box and cause misfeeds.

Many temperamental-feeding custom rifles have had some attempt at magazine alterations, often made on trial and error rather than based on sound engineering principles.

Getting a custom M98 rifle to feed flawlessly with a new chambering is the mark of a top-notch gunsmith who fully understands the ‘elegant simplicity’ of Paul Mauser’s original design.

 

[baxterb]

Thanks @Von Gruff i was trying to find your earlier post with this graphic.

 

[nztimb]

Some original Jeffery rifles had done away with the sides of the mag well and used the stock wood to retain strength while getting the needed width for correct cartridge stack and feed. Then only the follower and feed ramp needed attention

 

[Ray B]

A word of caution- before you commit the project to a gunsmith- verify his/her qualifications and abilities. My experience: For several years I was very pleased with the workmanship of CP Donnelly. He was able to accurately complete any project no matter how technical- but then CP retired and I had to search for someone even halfway as good as CP. I had a barrel made by CP designed for an FN action that I wanted to have fitted to an action. I obtained a brandnew Interarms X magnum action. The gunsmith fitted the barrel to the action and thing were fine except the action was for standard length cartridges. I had magnum length bottom metal so all that the gunsmith needed to do was machine metal from the action well to match the bottom, then taper the well to the rails and feed ramp. I took the parts to the gunsmith only to find that the gunsmith had sold his business to another gunsmith and moved to Arizona. I considered doing the job myself but since I was at the new gunsmith and the job wouldn't be very technical I let him go ahead with it. This turned out to be a mistake. For some reason he felt hurried on the job so that all he did was setup his grinder and punched a hole in the well up to and including some of the rails. this left no taper to the box magazine and a flat front where there should have been taper to the feed ramp. so cartridges in the magazine are pushed against a flat surface and won't feed. For practical purposes he ruined the action. After the holidays I will take it to another gunsmith that has a good local reputation and see if it is possible to polish the course surfaces, taper at least the feed ramp to get things to work. Or if I'm back to trying to find another opened up 98 action for the barrel and writing the whole thing off as a learning experience.

So my message to you, before you sacrifice your 300 H&H, make sure you can trust the gunsmith to do the job right.

 

[baxterb]

Been there, done that, @Ray B

solid advice.

 

[Witold Krzyżanowski]

My "404Jeffery" was built on a standard length 98 Mauser action. The action and magazine box were modified to fit. Barel length 26" by Lothar Walter, stock made walnut. Magazin box of 3cartridges.

 

[CBH Australia]

@Ray B
Sorry to hear that happened.
I do not know how you managed to right all that without going into a rant. Most would be pretty peeved off.

 

[Bonk]

Ok, I did the math for my 300H&H vs my 375H&H vs a 404J using the formula mentioned above. I did not add in a wiggle room factor just to keep the numbers straight. Here are the results (rounded to 1/100):

Caliber Theoretical rear box width Theoretical front box width
300H&H .99" .84"
375H&H. .99" .84"
404J. 1.01 .99"

I measured both my 300 and my 375. They were identical at 1.05" at the rear of the box. The front widths were .87" for the 300 and .84" for the 375. Essentially they were the same because the front has rounded corners and it was difficult to get a very precise measurement. For this parameter +/- .03" is well within the margin of error. It was actually more like .022 but I rounded up for one number and down for the other.

Also, the measurements of the box itself represent the absolute front and rear of the magazine. In reality the front of the cartridge will be well short of the front of the magazine box. By well short I mean in excess of 1/4". In that the box walls are tapering the walls at where the shoulders will be will be wider than the measured front width of the box. How much? I don't know. I didn't take the time to measure from the rear of the magazine to a point where the shoulders would be and then measure that width. The same applies to the rear of the box. The cartridges are most likely not always seated completely flush with the rear wall of the magazine box.

All this is to say that even agreeing with the author of the above article, @baxterb and @Von Gruff I'm confident there's plenty of room inside my 300H&H magazine box to accommodate 404J without any feeding issues. It's essentially the exact same size as my 375H&H and plenty of CZ550 375H&H rifles have been successfully converted to 404J. I'll leave it up to the gunsmith to tweak the magazine box if he thinks it necessary. I don't think it will be.

@Ray B, the gunsmiths are the guys at Matrix Gunsmithing who assumed the role of doing AHR upgrades. If Wayne gave them his stamp of approval I'm confident they know what they're doing. I'm not even remotely concerned about their expertise but your advice is noted. Sorry to hear about your nightmare.

 

[AZDAVE]

I wouldn't jackup the 300H&H, I would use one of the 375's and sell the other to pay for the gunsmithing on your new 404. that would be my .02 worth of advice. (I built one on a Ruger RMS years ago and built one on a Buska magnum action that is my current 404)

 

[Tokoloshe Safaris]

I've been pondering this for a while now. I really want a 404J. I'm a sucker for old school calibers and the dream of a buffalo hunt isn't dead yet.

I have a couple of nice 375H&H rifles (Ruger RSM & an AHR upgraded CZ550) and I considered converting one of them to 404J but I think I'm just going to sell one or both of them. I also have 9.3x62 and 9.3x74R rifles that fill the medium bore niche in my collection so if I get a 404J I don't need 375H&H. That leaves my beloved AHR custom built CZ550 300H&H as a possible donor rifle and I think that's the direction I'm going to go. Before anyone hollers "Blasphemy!" let me explain.

First of all I have more than one 300H&H. Second, my CZ550 is a really big rifle for 300H&H. I'm not a weight weenie and I knew going in that a 300H&H built on a CZ550 magnum action and a walnut stock was going to be a monster for a 30 caliber rifle and it is. About 9.5 lbs loaded with a scope a sling. I still love the rifle but I've convinced myself it will make the perfect platform for a 404J. It already has the magnum receiver, heavy walnut stock, ebony fore end and all the other wonderful AHR goodness. All it needs is to be rebarreled and I think the bolt face has to be opened up a bit.

The idea of me getting a 404J of some sort has been decided. That will happen. The question was do I defile my 300H&H custom build to do it? The answer in my mind was yes. I really don't want to spend the kind of money it would take to build a 404J from the ground up plus I really think rebarrelling my 300H&H is the best move for the rifle. It's built like a 404J and it really isn't happy as a 300H&H.

I solidified my membership application by buying a couple of boxes of 400gr Hornady DGX Bonded .423 bullets yesterday. Matrix Gunsmithing is looking for a barrel and will do the work. I'm on the hunt for dies and brass. Wish me luck.

BTW, does anybody need any .411 bullets? I have 4 new unopened 50rd boxes of Hornady Interlock 405 Win 300gr SP I bought about a year ago when I was considering 400H&H. I saw them in the dusty corner of a LGS and I bought them on the spot because I knew they were hard to come by.

This is the donor rifle:


View attachment 444573

Hi, I have had two .375 H&H CZ 550 converted to .404j. Both required work on the rails. The same gunsmith did both rifles and neglected to do the rail work that he knew needed to be done. He was so kind as to send me a drawing of the work that he neglected to do.

I love the .404J cartridge, I own 3. One is a original Jeffery pre war. It holds 3 rounds and cycles flawlessly. Number two is a pre-war Rigby that was rebored by Rigby, it cycles flawlessly. Then my wife's CZ and mine. Both work satisfactory although we have had a problems with Hydro shock bullets. The CZs seem to shave the plastic head. Twice this has caused chambering problems.

 

[Tokoloshe Safaris]

Not to be argumentative, but just because rounds will fit the magazine doesn't mean the max box dimensions are proper for the cartridge for optimal feeding. They should follow 'mauser's rule' of mag box geometry. When Mauser sold just commercial actions, they made about 27 different dimensional configurations - each specific to the cartridge, The 404 - with its length and big shoulder needs a very wide box at the front.

These are mag boxes from Darcy Echols. The third from the left is the 404. You can see how the sides are almost parallel - whereas the 458 Lott (1st) and 375 H&H (2nd) have much more taper.

When 404s are squeezed into a narrow box, the rounds will not stack right, but will be more vertical at the front. This will cause retention problems because the case is not under enough rail to keep it in place. (second pic)

View attachment 444608View attachment 444609


Which results in this:

404 in G33/40

Does anyone know if Darcy Echols makes and sells .404 mag boxes for CZ 550?

 

[Shootist43]

Bonk, before starting down the road of converting your AHR 300 H&H Mag. to a 404 Jeffery, why don't you call Wayne Jacobson and see what he has to say about it? If he is in favor of the project, go ahead. If not, why don't you list it for sale on AH and seek other options for getting that 404 Jeffery you want.