When necking cases down from a larger caliber to a smaller one, where does all the "extra" brass go? I have a wildcat idea for a 416Riby to be necked down to hold a .30-caliber bullet in a case the same length as a .30-06 Springsteen. The squeezed brass has to go somewhere. Does the annealing process soften the brass to such an extent that it can be reformed without crushing or folding over onto itself? If I get some answers to this question, I have many more about making this cartridge a reality if you'll indulge me. Thanks...

Cartridge Creator courtesy of ammoguide.com

Normally when you neck down the neck will increase in length. When you neck up the neck gets shorter. As long as the die is a fairly smooth transition the brass will not normally deform. From 416 to 308 you might need to do it in steps. I would anneal after you get it sized down.

Homebrewer, I believe that the brass compression results in two things happening to the neck of the down sized case material; the neck thickness is increased and the neck length increases. I reduce the neck of a 444 Marlin to 6.5 for the 260 Bellm #2. This can be accomplished without anealing the brass but I will loose about 18% of my brass to folded necks. If I aneal, I only loose about 2%. I also have to reduce the case in several steps. Starting with the 444 case, I run the brass through sucessively smaller sizing dies starting with the 358 Win., then the 308 Win, then 7mm-08 and finally the 260 Rem. die. Another thing with leaving out the anealing process. The brass is work hardened during the sizing operation and I lost another 28% of my brass due to neck splits on the first firing. I even had a few to split before firing. Good luck.

You'll end up with a long neck that will need to be trimmed. It might be eaiser to start with 30-378 Weatherby brass and turn off the belt. Same basic case.

Thank you to all who replied. So it seems to me that the case can either be formed in steps without annealing, or formed in one crunch if it is annealed. A) Can a case be formed by annealing between each step of the forming? B) Can a case be annealed too many times?

I understand the neck will get longer when the case is reduced in size at the mouth. Trimming it with one of those little late-type trimmers with the clamp to hold down the case wouldn't be a problem. C) How do you get the thickness of the brass in the neck to the right dimension and have the neck end up on the centerline of the case?

D) Would anyone recommend a system with two forming dies over just one?

Thank you again, to all who replied. More questions to come as I think about this some more...

The Weatherby 30-378:
Visual comparison between 416Rigby and 30-378 Weatherby:

I neglected to say I want to start with 416Rigby cylinder brass to eliminate any questions about whether or not the case would be weak on the wildcat where the shoulder bends were on the original. I want a "clean slate," so to speak.

While I guess you could anneal between each step seems like major overkill to me. Done correctly I doubt you can anneal to many times. Most annealing problems come from too much heat and/or allowing the head to get hot.

If I was going to shorten that case to 2.5 I would trim it back to that or shorter after finding a starting point that yields a finished product just longer than needed. Then neck that shortened case down. No use fooling with all that extra brass.

I would trying taking it in one step. If that didn't work look at something like these.
https://forums.accuratereloading.com/eve/forums/a/tpc/f/...=941109578#941109578 The first firing will be a fireforming load to make a sharp shoulder most necking down will not result in a sharp shoulder from the die.

Neck turn using a pilot to remove thickness. The necks should be as close to center as your case bodies are.

WOW!! If a .30-06 case can be formed down to what is shown in the third and fourth pictures behind that link, mine should be no problem at all. The brass has to be mega-thick so close to the head, yet the shoulders look really good on the finished product. I'm encouraged! I can see one or two forming dies being made to squeeze the cylinder brass down, cut to length, turn necks to the proper inside and outside diameters, then fireform. Is that how it's done?

quote:

I can see one or two forming dies being made to squeeze the cylinder brass down, cut to length, turn necks to the proper inside and outside diameters, then fireform. Is that how it's done?

yep pretty much. I take the last step with my sizing die let the expander open the neck up to the correct inside dia and then trim turn the neck and do final fireform.

brewer

I'll chime in here with my experience in sizing down the Rigby size case to a smaller case/caliber. I'm not saying that you will experience the same things that I ran into but be aware.

Going from a Rigby cylinder case to a 2.5" 30 caliber is not going to be easy. You will definitely need a set of forming dies such as Butch Lambert is making. As Ramrod said, you should trim off most of the excess before starting, but leave yourself enough so that you will be sure of a final case length of 2.5". I'd do the first trim to, say, 2.6" or 2.7".

There is a good chance that your necks will be so thick that you will have to turn them before you can chamber a loaded round for fire-forming. It will depend on the dimensions of your chamber and how thick the brass is before you start necking down. But don't be surprised if it happens.

I've never found it necessary to anneal while necking down. New brass should be capable of the work necessary without an anneal. As Ramrod said, there is too much annealing going on. If you are determined to anneral, do it just before fire-forming.

If you have a buddy who has done this type of thing, have him walk you through everything. You are making a drastic case change for a beginner.

JMHO

Ray

quote:

Going from a Rigby cylinder case to a 2.5" 30 caliber is not going to be easy. You will definitely need a set of forming dies such as Butch Lambert is making. As Ramrod said, you should trim off most of the excess before starting, but leave yourself enough so that you will be sure of a final case length of 2.5". I'd do the first trim to, say, 2.6" or 2.7".

There is a good chance that your necks will be so thick that you will have to turn them before you can chamber a loaded round for fire-forming. It will depend on the dimensions of your chamber and how thick the brass is before you start necking down. But don't be surprised if it happens.

This is exactly the type of info I am looking for in asking the question. Thank you for the detailed answers. Do I need forming dies specific to what I envision for this case, or will the ones like Butch has work well enough to get down to a basic shape with a shoulder angle close to the 30 degrees I want?

hb

You won't end up with a defined 30 degree shoulder unless the final step is with a FL die. Even then you will have a "bumpy" shoulder that you will be ashamed for anyone to see. The fire-forming will take care of that.

The dies that Butch sells should work for you. Call him to be sure that the biggest of the set has enough ID to make the first step. The Rigby case will probably be about .550" and the biggest die may be only .500" or so. But, Butch is a nice guy and will listen patiently to your questions and maybe he can make you a special bushing if you need it.

Good luck, and don't say I didn't warn you.

Ray

quote:

or will the ones like Butch has work well enough to get down to a basic shape with a shoulder angle close to the 30 degrees

If you are just forming the case to the point you can fireform it doesn't really matter what the shoulder looks like as long as you have enough to headspace on. Fireforming does the fianl shaping.

My my my, that would be quite the standard length 30 cal!! I wonder what the capactiy on something like this would be?

Yeah; I figured I'd have to blast to get the final shape. I was just asking if there were commonly available forming dies around that would get me down to where I could get the round into the chamber and form in it fire and brimstone from there. Seems there is. I'm guessing the water capacity of the case to be about 80-90 grains. I anticipate more velocity than the 2900 fps from the 300WSM this wildcat is meant to replace, but not as much in the way of throat burn as you'd get from a 300WinMag or especially from a 300RUM with some of its charges being near 100 grains. I can't use either of those cartridges as a direct rechamber because the 300WSM has a .555 lower datum diameter while the two aforementioned cases are a bit smaller than that by .011 or so at their lower datum point. This oddball is the only way I can see to go. It's a long way to Tipparari, so I have lots of time to ponder this thing...

I took a second last night to calculate the volume of the powder column in this case. I calculate it is almost exactly 7.00 cc, which equates to about 108 grains of water. I may have to consider throat erosion issues, after all. Not what I had in mind. 7cc of RL-22 weighs 98 grains. An equal volume of H4831SC weighs 100 grains. Tell me, please, do not magnum powders burn slower and generate less heat than a small, ball powder?

Your best bet would be to start with the 338 Lapua, neck down and shorten to 06 length. The 338 Lapua has nearly the same dimension as the 416 Rigby.

Here is what you are looking for, instead of 57mm you go to 63mm case length and a 30deg shoulder. But the 7.62 UKM will do nicely for what you have in mind.

http://www.angelfire.com/ma/ZERMEL/762ukm.html

first, start with 338 lapua ..

Below is the 7.62UKM from the link provided in the post by ZERMEL.



L1 = 1.636 inches; L2 = 1.928 inches; L3 = 2.244 inches; P1 = .587 inches and P2 = .554 inches. This is a bit small for what I need, but I appreciate the input. Is 338 Lapua available as cylinder brass? Let's hope so. Thanks you for pointing me in a better direction. I need a case that has a straight wall at least 2.5 or 2.6 inches high to totally wipe out the present 300WSM chamber.


Just went to ammoguide.com and looked at the 338LapMag. It looks like it was made from the 416 Rigby case. The head diameter is the same, as is the diameter just above the head. Is 338 brass easier to get than 416Rigby? Would a set of Butch's forming dies be the ticket to squeezin' these cases down straight away? I read somewhere in these pages that most dies are not made big enough to do the .400 to .500 calibers.

Damn! I wish I had some money. Here's a bunch of it on gunbroker for cheap. Auction ends in one more day.
http://www.gunbroker.com/Auction/ViewItem.asp?Item=113955175

ask me about my 22-378 Wby, aka Ackley's .22 Eargesplitten-Loudenboomer some time.

Rich
DRSS
Knowledge not shared is knowledge lost...

i would call or visit rcbs's web site they may already make a complete forming die set for what you wanna do.
it would then be an easy matter of buying brass running it through the forming dies annealing and trimming and neck turning to fit your chamber.
just my .02

Have a look at COW 7th Ed. the McMillan Company has don exactly what you are looking for in 1991.
Mayby they have some Tooling left over....
If you still want to try it, use .338 Lapua Brass.
Best
2RECON

Got your PM, 2RECON. Looking for a 300Phoenix drawing right now. Will also be looking at McMillan site. Will look at RCBS website in short order, Lamar. Thank you to all who have provided so much help.

Hi again,
IF everything is going fine,and the whole project is going to start......
Good advice : DON´T buy ONE Barrel,
guess 10-12 is a good number to start

Best
2RECON

quote:

Good advice : DON´T buy ONE Barrel,

I assume you mean cases? A barrel for my rifle was $500 in 2004, plus the labor to have it installed and chambered. Ten barrels would cost me around $7,500....

What my wildcat would look like. The one on the far left is a 300WSM, my present cartridge. The wildcat is the second from the left. I call it the 300NDM, for Nevada Desert Magnum. I'm guessing about 80-85 grains of powder, based on a compressed load of 70 grains of RL-22 and/or H4831SC in the 300WSM. The neck is .405 inches long, to reduce throat erosion. A .30-06 case is second from the right. The parent case for my wildcat, the 338 Lapua Magnum, is on the far right.
Drawings courtesy of the Cartridge Creator at ammoguide.com

quote:

I understand the neck will get longer when the case is reduced in size at the mouth. Trimming it with one of those little late-type trimmers with the clamp to hold down the case wouldn't be a problem. C) How do you get the thickness of the brass in the neck to the right dimension and have the neck end up on the centerline of the case?

http://www.natchezss.com/brand...ory=0&prodID=RC98860


I understand the neck will get longer when the case is reduced in size at the mouth. Trimming it with one of those little late-type trimmers with the clamp to hold down the case wouldn't be a problem. C) How do you get the thickness of the brass in the neck to the right dimension and have the neck end up on the centerline of the case?

I was looking at my Sinclair catalog. There is a mandrel-type thing (p/n NT-EXP) you use with your press to move the brass around so it's equally thick all around the case mouth. Then you turn the neck...