Well, why not?
I was reading the article on headspace and the 400 Whelen at Z-Hat ( http://www.z-hat.com/smashing_the_headspace_myth.htm ) and noticed that the difference from shoulder to neck was much smaller than what you could get from an improved Rigby case.
The Mbogo, for instance, is .575" (?) at the shoulder with a .538" neck, giving .037" difference. The old Whelen drawing shows .458" to .440", for a difference of only .018"!

The Van Horn Express does basically this very thing, but on a 2.5" case.
So, Why wouldn't this work?
{By which I mean match the 500 A-Square.)

I tried that very thing by running a 416 Rigby cylindrical brass though my 500 A-Square die. The shoulder looked very skimpy. Remember when you take the difference between the shoulder and the neck OD's you have to divide that in half for your actual shoulder that you will headspace on. It did look like a very nice cartridge but I thought that there wasn't enough shoulder.
Take good care,
Dave

How thick was your neck when you seated a bullet?
Was there room to trim a bit?
The Van Horn has a 40 deg rather than a 35 deg shoulder, and about 4 thsndths smaller neck.
Would that make the difference?
Like .020" on each side, 40 deg shoulder, or go 45 like the Rigby.
Trouble is, seems there's only one way to see if it works....

Unfortunately it's a waste of time and money. There is too little shoulder to headspace on reliably resulting in lots of ignition problems. Go directly to the 500 A2 with a belt and it will work flawlessly.-Rob

When we started developing wildcats, we spoke at length with the folks at CH Tool and Die. Dave feels that in order to reliably headspace on the shoulder, you should have at least 0.05" difference between neck OD and shoulder OD (yes, OD, so 0.025" "thickness"). We use 0.047" on the 458 SOCOM and given it is capable of 0.5" at 100 yards, it would appear to be sufficient. (Mind you that this is in an AR-15, not a bolt action)

The 500 Jeffery (12.7 Schuler) has 0.6031" - 0.5374" = 0.0657". The 505 Gibbs 0.062", and the 500 VHE in my book shows 0.043"

The 0.037" you mention may or may not work, gut feel says it is too little. However, neck trimming MAY give you that little bit you need to get to 0.05" which seems to fit dimensions found on other cartridges.

Let's get back to basics...

416 rigby and 416 woundabeast, and then 460 woundabeast

the weatherby is basicaly the 416 rigby with a belt.

neck it out 458, and it's the 460 weatherby....
neck the rigby to 458... 458 rigby...

BUT
take it to .510, and that belt (call it a mid rim) gives a very safe headspacing datum. In fact jeffery, who could have taken the rigby and redone for a 510, and used the existing schuler which has enough to headspace... and, for the record, had the same rim diameter as the riby...

and, cost... it does matter..
rigby brass, 1.83 each
weatherby ...1.55
460 weatherby once fired $1 each
http://www.midwayusa.com/rewriteaproduct/569878

dies
probably a wash BUT

chamber reamer
510wells, 500 a2... 35 bucks rental...
~200 for custom

die reamer..
460 weatherby based -- nip
wildcast
75 to 100...

performance?? zero difference... load it at 500jeff to 500a2...
resale? nada for a 50 cal wildcat...

counter thought: move the rigby shoulder back down the neck, and have a nice long neck, and plenty to headspace off?

get 500 jeff performance, off the rigby case...

but still not for the extra grand or so, at least for me

jeffe

[ 08-29-2003, 20:50: Message edited by: jeffeosso ]

Jeffeosso, I should tell you I have know intention of building this. Just wondering about the theoretical viability of it (as opposed to financial.)
I'd heard somewhere that .475" was as big as you could go on the Rigby, then I saw Van Horn's and got to wondering.

Going off guidelines from folks like Dave D at CH4D, we put together a "cheat sheet" on what the smallest case diameter is for a given bullet diameter.

The guidelines we tend to use:
- case wall thickness at the mouth is 0.012" typical, so add 0.025" to the bullet size to get the OD of the neck.

- Minimum shoulder is 0.05", so add that to the OD of the neck.

- For every 1" of length, a taper of 0.015" is nice to have to aid extraction.

So for a true 50 cal that is 2" long, the smallest base would be 0.510" + 0.025" + 0.05" + 0.015"x2 = 0.615". The Jeffery/Schuler is 0.6193" and would be what we feel is the mimimum

For a .475 x 2", you end up with 0.475" + 0.025" + 0.05" + 0.015"x2 = 0.580", and the Rigby is 0.5891"

Now, these are only guidelines, and yes, there are rounds out there that do not follow these and that are quite successful, but using these rules of thumb, we have not gone wrong with any of our designs yet ... one of our designs didn't work, and looking back, we had the wrong case wall thickness ...