Good day fellow shooters. I have been reloading for over 20 years but mostly for hunting applications and a few target applications. My most recent project is necking down .300 WSM brass to make 7mm WSM using Norma brass. I have never necked down, or "wildcatted" a cartridge so I have a few questions.
I am using a Redding Competition Die set: Seater Die, Body Die, and Neck die.
The.300 WSM case has a neck thickness of .0155"
According to my reamer dimensions, I would like to get a 7mm WSM neck thickness of .015". The reamer is for a standard WSM Match chamber, No tight neck etc.
Using the Redding Competition Bushing Die, I have bushings of .311, .312, .313.
Obviously necking down increases the neck wall thickness. Getting the O.D. necked down to .313 will leave the I.D. of the neck too small for the pilot of the neck turning tool, or to seat a bullet.
My dies do not have an expander ball to properly form the I.D. of the case. Do I need to buy a separate die with an expander ball to get that initial .2825 I.D.?
Is there a better way that I am not getting?

Also- I plan on fireforming 300 pieces of brass (Not sorted or culled yet). I have an unshot, Krieger barrel on a Surgeon action. I realize the life expectancy of the throat will be around 1200. I would like to avoid using up 25% of the barrel life fireforming brass.
Has anyone else used a "Mule Rifle" (A inexpensive, or worn out rifle in 7mm WSM) to fireform brass to get it close enough to my chamber specs to start serious reloading?
I can't find a tired 7mm WSM chambered rifle yet so I am looking at purchasing a Savage or other inexpensive brand in that cartridge just to do the brass forming operations.
Any thoughts on that?
Thanks-
WARDOG

This from 6br may help

I also would suggest getting the FL Redding Type S Bushing die. It has an expander ball. You will need this with brand new brass before neck turning. I would Cream-o-wheat fireform the brass to avoid barrel wear after simply running them through the 7mm WSM die, then I would FL size only bumping the shoulder .001" before neck turning. You should be able to neck turn to the shoulder and get the neck thickness you want.

Thanks rcamuglia-
Yeah it makes sense. I was just trying to avoid another $64 die. Fireforming brass has become an expensive venture and I was trying to stop spending $. I thought there might have been another way.
I added the Redding FL "S" bushing die to my SINCLAIR Shopping Cart.
Can somebody experienced in the "Cream of Wheat" fireforming process suggest the right powder type, grains, and process of doing this for this cartridge. I hear about it all of the time but few have actually performed it. How often do you have to clean the barrel? Does it get it don the first firing?
ADDED: Regarding your link to 6mmBR-
I have been lurking around at that sight for some time now. That article on Vince Bottomley's success, Articles by Bryan Litz, and Litz's book on Ballistics, along with suggestions from our rifle gunsmith / competition shooter Shawn Davison (JRH Advanced Gunsmithing) is why I took on this project.

Here's a cream of wheat (polenta) fire form thread.

Check around the mid part where I added pics of doing it.

About 10gr of Red Dot is what I used. You can use any fast burning powder like Unique.

Been doing fireforming with several kinds of hot cereals and powders for so long I can't remember just how long.

I've used cream of wheat, grits, cornmeal (polenta), cream of rice, etc...and just about any fast powder I have on hand...bullseye, red dot, 700, 800, etc.

Depending on the case size I usually start with 10 gr bullseye for small cases, 15 for 308 size, 20 for '06 and mag, about twice that for 800...fill the case to the bottom of the neck with cereal, I use a 1" sq of blue shop towel balled up on top, then shoot.

If the case forms out then I stay there, if the case shoulders are rounded and not filled out I add a bit more powder to a new case then fire again and so on until the case forms well...but not too much powder. Basically start low and work up slow.

As far as your application is concerned all you have to do is to look at a reloading manual for the 7mm WSM SAAMI neck OD, get a bushing 0.002 or 0.003 less ID and size a case...One pass through the 7mm WSM sizer die will usually do it. For the bushing, most of my books say 0.321" for the neck so I would get a 0.320 and 0.318 to begin with. Fire form one case and measure it, then stuff a bullet in it and measure it again...adjust as necessary depending on if you neck turn or not.

You're not really wildcatting as 7mm WSM cases are available, per se...just using a different case.

Do some searching on other forums espsecially 6mmBR...all you questions have already been answered and there is lots of information on some of the long range and varminting forums.

Do a search on this forum...there is lots of information about "COW" fire forming.

One other piece of advise...DON'T do all the cases at once. Do 10 or so to get all the problems ironed out. When I'm working up a load for a new rifle I weigh sort 10 cases AFTER I've trimmed, uniformed the primer pocket and turned off the flash hole burr.

I also neck turn just enough to clean up about 80%...you'd be surprised just what 60KPSI will do to a case in redistributing brass.

I use these 10 cases to work up the most accurate load for the bullet I want. To get even more anal, I also weigh sort the bullets AND measure sort for ogive length.

There are lots of pro's and con's on HOW to go about prepping your brass, whether to use a sizing button or not, just how much to size, when and how much to clean, whether weigh sorting or ogive measuring, primer pocket uniforming or flash hole bure removal is worth anything or not, etc. You have to work out much of this on your own for YOUR rifle and YOUR usage by testing and it depends on what your rifle is used for, what pressure you load to and so forth.

Again, I don't think you will get all your questions answered fully on one forum on the net, you have to dig around, use good search techniques and read a lot online and in reloading manuals and other publications...AND shoot a lot.

KEEP COPIOUS NOTES on ALL you do and when you do a test only change ONE parameter at a time until you see which way the groups are going, then you can test two parameters like a change in seating in 0.005" increments and a couple tenths of powder.

If you're going to do 1000 yd targets you have your work cut out...for hunting just load'um up and go shooting.

Luck

First. 300 wam brass is too short.
Cream of wheat is a pita. I use bullseye and a shotgun patch

Thanks FOOBARI appreciate your advice and printed it off for my folder. The powder type and load you offered is just what I was looking for.
I finally joined several other sites just to pose these questions, so you'll see me around more. I searched several forums including this one but didn't get the specifics I needed.
I learn quickly but I hate to pay money to reinvent the wheel if you know what I mean.
My math just came out to .319 bushing before neck sizing for the .318 chamber, so I am getting that plus a couple of lower bushings in .002 increments.
I have a full machine shop at home, but the magical blue smoke escaped from my Monoset grinder a few weeks ago, otherwise I would be making the bushings myself.
And yes I am going for 1k Yds with this rifle.
I have developed some very accurate loads for my Bolt .300 RSAUM, AR-10(T) and an AR-10(TU) in .300 RSAUM, but I never had to do all of this brass work and "COW" tipping.

i tried doing what you want to do for a 7-300wsm i had made. My results were inconsistent and i ended up breaking down and having a set of FL sizing dies made by RCBS.

Redding just came out with a carbide button kit for the Competition dies. I got it with some larger bushings in my Sinclair order today.
Wait and see.
I also have a book on order from Glen Zediger for precision reloading for competition.

Thanks for everybody's help. I realize I am new to this site asking a lot of questions. I appreciate the professional responses.