New here and looking for a little advice on my project. In fact, I joined this site as a result of internet searches for advice as I embarked on it. As the title indicates, I am in the middle of a project to convert a Model 70 Classic in 300 RUM to 404 Jeff. Details are: M70 Classic action, original RUM mag box, Williams one piece bottom metal, Pac Nor barrel, NECG 3 leaf island rear and hooded front sights, barrel band and a surplus Winnie super grade stock. The stock, I believe, was one made for the Cabela's 50th anniversary special run of big bore safari rifles. We have it feeding, which took a little smoothing of the feed ramp and front corners of the mag box at the cut out windows. Here is my question. We can get three down in the mag, but it is tight. Also, we are currently using the original follower and spring. I read an old post here that the Williams bottom metal would allow only two down and Blackburn is better? Haven't tried the original two piece as we don't have an adaptor at hand. To those who have been down this path, does the bottom metal make a difference in mag capacity? Would another follower and/or spring make any difference? I'd like to know before I shell out more $ and don't really want to use the original two piece if I can avoid it.

I am about to start on this exact project, so I'm interested in people's experiences...

I'm having one done at Bijou Creek Customs, but don't have it back yet, so I can't help. But from what I hear, it's a great caliber conversion.

It is looking really good so far, and destined for Zimbabwe in May of 17 on a combo leopard and buff hunt. I just want to make sure that it will hold three down "comfortably". I thought about a drop box mag, but that would have required a custom stock. At that point I might as well have gone full out custom on a magnum length mauser action, or just bought the CZ in 404 that Wayne Jacobsen still has for sale on the AHR site (which looks awesome).

first and foremost -- in fact, the most important part

your chamber reamer, headspace gage, and reloading dies ALL have to use the same print - otherwise, well, its not going to be as easy as it could be.

decide which dies you want -- call them, get their print, then get your reamer from the same print.


feeding is pretty easy .. any decent bigbore smith can do this one

put a pin down the wrist, axialy, and bed it ..

decide if you are going to load 404 or 424rum (i just made that up, but it makes sense) if you are going to load hot, there's more stock work.. if you are going to load classic, its a hoot

Thanks for the reply, Jeffeosso. I should clarify, we have been using factory ammo, both Hornady 400 gr DGX and Cor Bon 400 gr tsx, and have it feeding fine. My specific question at the moment is that, with the Williams bottom metal and the oem 300 RUM follower and spring, 3 in the mag is tight. Any suggestions?

I'll also add that you have raised some questions re: reamer and dies. My gunsmith has handled all of this so I have no clue. Dumb as it may seem since I am on this site, I don't handload and was planning to use Superior or Hendershots custom loaded ammo. More questions!

Timely topic. I have a 300RUM barreled action on my reloading bench.

I'm all ears

All valid points by Jeffe, but I would expect your gunsmith does that.

You might check Jim Wisner to see if he has any drop belly floor plates to add one or two.

Make sure you have this spring and follower (see below), they were OEM in a Win M70 .300 RUM I had converted to .404 Jeffery in 2004. 2-piece factory bottom metal also shown, and the box is the windowed sheetmetal from factory: Plenty of room for 3-down with 404 Jeffery, which takes up less room than 3-down with .300 RUM.
The base diameter of .300 RUM is .551" max (according to some sources, and it is 13.99mm or .5508" according to C.I.P.).
The base diameter of .404 Jeffery is .543" max (according to some sources, and it is 13.84mm or .5449" according to C.I.P., the only authority on this).
Whatever the difference after manufacturing tolerances, the .404 Jeffery is measurably smaller in the base than a RUM.



If you have the flat spring (no space-killing hump in the base portion of the spring) and the scalloped follower as shown above, and the original sheetmetal windowed box,
then the problem must be with the way the replacement wood stock and replacement Williams bottommetal are interacting with the rest of it.

One of my greatest African Sheep Rifles of all time, perfectly balanced, light and rugged, with serviceable accuracy:

First shot fouling at 100 yards:



The 30-cal hole left of the POA at 300 yards is extraneous except to show the direction of wind drift expected:





I admit that the stock is a secondhand Brown Precision that started life as a .308 WCF fit, purchased for $200 at a Montana gunshow, and was rebuilt by me to accept the .404 Jeffery.
Everywhere you see JB Weld on the outside of the original paint job, there was some steel hidden or major artwork going on.

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Thanks, RIP. I'll check that out. It's all at my smiths right now, but I'll see him Monday.

Interesting shape on the blotch on the rear of the stock - reminds me of something .....

quote:

Originally posted by Idaho Sharpshooter:
All valid points by Jeffe, but I would expect your gunsmith does that.

their gunsmith - and no, it would be a poor expectation, as there aren't very many 404's being made, and many gunsmiths have no idea that there's at least 2, if not 3, different specs -- and buying a set of dies form one (generally not a gunsmith task) doesn't mean that they'll be compatible with the reamer that is rented for this one time job, and the gages bought at a gunshow...

my advice is PERFECTLY valid, and having actually been through this, it will save this poster, and likely many others, time and trauma to avoid.


having had reamer from one source, gage from another, and dies of interesting pedigree happen, well, all the time...

quote:

Originally posted by Bren7X64:
Interesting shape on the blotch on the rear of the stock - reminds me of something .....

Alaska?

quote:

Originally posted by Sean Russell:

quote:

Originally posted by Bren7X64:
Interesting shape on the blotch on the rear of the stock - reminds me of something .....

Bren7x64,
Thanks for noticing. You got Sean thinking about geography too!

Alaska?

Sean,
That is Antarctica surrounding the rear sling stud which is the South Pole. Where penguins live. Not Alaska!


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I'm doind the same thing to a .300 RUM Model 70, except mine is being made in .425 Westley Richards. It has a Pac-Nor barrel, Recknagel banded rear sight base with integral recoil lug from NECG and banded sling swivel and front ramp from the same source. It is out being blued at present, and Jim Kobe expects is to be finished in a couple of weeks.

Mine is equipped with two bolts, one with a .30-'06 bolt face to accept original WR ammunition and the other the original bolt to accept RUM cases reformed to .425. There is only .002" difference between the two as far as headspacing is concerned.

Naturally, I am looking forward to wringing it out.

quote:

Originally posted by xausa:
I'm doind the same thing to a .300 RUM Model 70, except mine is being made in .425 Westley Richards. It has a Pac-Nor barrel, Recknagel banded rear sight base with integral recoil lug from NECG and banded sling swivel and front ramp from the same source. It is out being blued at present, and Jim Kobe expects is to be finished in a couple of weeks.

Mine is equipped with two bolts, one with a .30-'06 bolt face to accept original WR ammunition and the other the original bolt to accept RUM cases reformed to .425. There is only .002" difference between the two as far as headspacing is concerned.

Naturally, I am looking forward to wringing it out.

When the 425 WR and the 404 Jeffery have the same base diameter (0.545") why would you want to use RUM brass with a 0.551" base diameter,
when you could use 404 Jeffery brass?
Is Norma 404 Jeffery brass harder to find than .375 RUM now?
Or do you have a big stockpile of the RUM stuff?

If the original 425 WR ammo fits the chamber properly when using the '06 bolt, you are going to have some extra work sizing down the RUM brass base diameter to 425WR/404J base diameter, when using the other bolt. I have tried that and there is some extra sweat involved there.

Also, you could do a much better correction of the severely rebated rim of the 425 WR by using the 404 Jeffery brass to make your 425 WR brass, instead of the considerably rebated RUM.


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Here is another illustration of the flat follower spring, this one from a SC-made .375 H&H M70:





And the one to avoid if making space in your mag box:

Make sure you don't have the space-occupying humped-bottom follower spring like on this M70:





Compared to the RUM follower and spring above:



There sure are a lot of different follower types on the factory Winchester M70s, but only two follower spring types:

1. Humped-bottom space killer
2. Flat-bottom space maker

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Thanks, RIP. That picture clears up the difference in the springs.

[QUOTE]Originally posted by RIP:
If the original 425 WR ammo fits the chamber properly when using the '06 bolt, you are going to have some extra work sizing down the RUM brass base diameter to 425WR/404J base diameter, when using the other bolt. I have tried that and there is some extra sweat involved there.

Also, you could do a much better correction of the severely rebated rim of the 425 WR by using the 404 Jeffery brass to make your 425 WR brass, instead of the considerably rebated RUM.....
/QUOTE]

I have a bag of 50 RUM cases I bought some time ago. I have been creating .404 brass with it with no difficulty. I will have to measure the base, but I suspect is it undersized.

I was told that I would need to swage the bases of .30-'06 based cases to form 9X56 Mannlicher Schoenauer cases out of them. However, idle curiosity led me to measure the base diameter of a case from a bag of Remington .35 Whelen cases, and lo and behold, it was the correct diameter for the 9X56. Problem solved. I suspect Remington is not too careful with their base diminsions.

Interesting.

I got my 9.5X57 MS dies from Buffalo arms and also 50 formed cases & they had 35 Whelan Rem head stamps!.

I checked the web for lots for case dimensions and pictures / drawings. Finally found that the 9.3X57 Mauser and the 9.5X57MS have very similar cases. The Mauser case is more tapered but the head space is the same.

The 9.3 case would become shorter on firing.

quote:

Originally posted by xausa:
[QUOTE]Originally posted by RIP:
If the original 425 WR ammo fits the chamber properly when using the '06 bolt, you are going to have some extra work sizing down the RUM brass base diameter to 425WR/404J base diameter, when using the other bolt. I have tried that and there is some extra sweat involved there.

Also, you could do a much better correction of the severely rebated rim of the 425 WR by using the 404 Jeffery brass to make your 425 WR brass, instead of the considerably rebated RUM.....
/QUOTE]

I have a bag of 50 RUM cases I bought some time ago. I have been creating .404 brass with it with no difficulty. I will have to measure the base, but I suspect is it undersized.

I was told that I would need to swage the bases of .30-'06 based cases to form 9X56 Mannlicher Schoenauer cases out of them. However, idle curiosity led me to measure the base diameter of a case from a bag of Remington .35 Whelen cases, and lo and behold, it was the correct diameter for the 9X56. Problem solved. I suspect Remington is not too careful with their base diminsions.