358Win from 308 brass

[GRUMPA]

Figured since No_1 created this section for this sort of thing I guess I'll give a HOW-TO thread.

First thing I do is clean all the brass with my stainless steel media and get it good and cleaned. After that I run them through 2 different dies, the first is a 308 sizer die, the second is a small base die. Here's a picture of that operation done and the primer pocket gets swaged as well. I make my own lube for all my conversions, doubles as my swage lube. It's nothing more than Anhydrous Lanolin and Vaseline that's a 50/50 mix.

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Then I set up what I need, my L.E.Wilson case gauge, and my Rock Chucker press. Now at this point I'll point out something for the beginners, Always use a tapered expander plug when you do this, I have a picture of it which will be further along in the post. Sometimes in order to make these (or any other conversion for that matter) to spec. some material is going to be removed from the base of the die or the shell holder. There's more than a couple of shell holders I've taken material off and had them break from removing to much material. Here's a picture of my indicator I use along with the gauge.

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The "ZERO" is the high of the tolerance, this shows .003 below the high which is right about where it needs to be.

At times I would remove material from the shell holder, in some cases. Seems quality control lacks lately and I've been removing material from the base of the die. I had a die set come in and I ended up removing .030 from the base of the die to make it work.

Now here's a picture of the die I use to form these.

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When I form these I don't just put the case in the shell holder and run it up in the die to make these. I don't care if it's military brass or commercial they act the same. When I do the initial sizing I lower the ram just low enough so the expander isn't run through the neck. When I do that I spin the case about 90deg to 180deg and run it through the sizer again. Brass has this nasty habit of "Spring Back" and the brass will want to spring back a bit, spinning the cases when you lowered the ram and spinning it and sizing it yet again will take a majority of it out. When I do that I rarely get a variance of more than +-.001 on any of the conversions I do.

The finish length of the 358Win is 2.015-.02 and so far I've always had them in spec after forming.

After I form them I clean them again in the stainless steel media and let dry. After that I anneal them, I rarely anneal any conversion first.

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I did 500pcs today and got 3 split necks, I get those from time to time but don't give it a thought. Those I dump in a bucket and make those 45ACP shot loads from 308 brass. But you can see from the pictures the transformation that takes place converting 308 brass into 358Win brass.

[DCM]

Good write up!

[ballistim]

GRUMPA is the brass master! I have his .300 Savage reformed & .358 Winchester on the way simply because he makes it better than I can.

[pworley1]

That was very good work.

[jaysouth]

I assume that your die is the Lyman M. I use an RCBS neck expander with a .358 spud. I have not had a split neck since getting this die. I will try rotating my case like you do. That seems like a good idea.

I full length resize in .308 then anneal the necks before expanding. I also dip the necks in mica before expanding. Let me know if you know of anyone who has the Wilson case gauge in .358. Midway and Brownells are out of stock now.

Just for interest, I tried resizing 308 to 358 using a Lee full length resizer. I split 50% of the necks I attempted to resize.

Down range, I cannot tell the difference in accuracy between resize GI brass and Hornady factory. I know there is a capacity difference but that does not affect my cast bullet loads.

Thanks for your post

[GRUMPA]

Here's my thinking on the annealing part.

When I make 1 thing into another I'm wanting it to be as good as it's going to get. When I do get a split case neck it tells me that the piece of brass I'm converting is weaker than the rest. Let's say if I were to anneal the case first I more than likely wouldn't have split the case neck. I want the weaker case to fail, that's why I refuse to anneal them till very last.

And I sent you a PM about a 358 Win case gauge.

[1Shirt]

Years ago, I made mine by first annealing the brass, then running it thru an 8 MM Expander, than thru a 45 expander, and fire forming. No magic for me, it worked well.
1Shirt!

[W.R.Buchanan]

I am planning on doing something similar to what you do for my .35-303 conversion. They will also be neck sized and loaded with .358 Win dies.

Since I have a machine shop I will make a mandrel that has three steps .020, .020 and .010, and turn them in a lathe as the mandrel is inserted. With lube this insures concentricity and the least amount of stress to the brass.

Since all my cases are once fired PPU's and annealed before they are loaded there shouldn't be any need to anneal afterwards. I agree with no annealing cases before forming to find the weak ones, but this is only for new or once fired brass. But then again nobody would convert brass that has been loaded many times to something else. Seems like that would just be needlessly asking for trouble.

Randy

[FrankG]

I made some 358 from 'Cavim' surplus brass and got a little doughnut at neck shoulder junction just below neck . It was pronounced enough that bolt would not close on the casing . This is a first for me when reforming cases . Ive reformed many over the years and never had this happen .
Any ideas ? Do you think annealing them then running through sizer die again may remove doughnut (raised ring)?

[rockrat]

I have that "doughnut" at the base of the neck. I ordered a .361" inside neck reamer to take it out. My fired cases measure .3605" inside dia at the case mouth. figure that should even things out. My rifle has a very tight neck. didn't order it that way, just came out that way.

[GRUMPA]

OK here's the problem, and YES I've had just this same thing happen to me. The neck diameter of the 308 IS IN SPEC for the 308. Now when you knock the shoulder location shorter your now getting into the body of the case and the brass is thicker. That's where that doughnut ring comes into play. Not all brass is good for converting over into something else without some added work.

I run into that more times than I care to remember, that's why I take notes and scribble down which head stamp works and which doesn't. Most foreign military type cases wont work to well without reaming them and that gets rather involved. On another conversion I do I made a smaller expander plug, that way the thicker brass is on the inside of the neck and I ream it out. Then put in the proper expander plug and run them through the sizer die again and they come out just fine.

[FrankG]

Those cavim had the raise on shoulder itself below neck junction .

[Ola]

.Any ideas ? Do you think annealing them then running through sizer die again may remove doughnut (raised ring)? The simplest solution is to try out different brands of brass. There is huge difference between them in this respect. The ones that have thinner walls won't have the doughnut.

[La Dano]

I've got the "donut" in my 308-35Rem reformed brass.

[GRUMPA]

Picture?

[La Dano]

case on the right is finished, not a good pic.

[TheDoctor]

Have not thought about this before. Not annealing before expanding to sort out the weaker cases. My question is: does that really sort out the weaker brass, or just brass that has longer grain structures, that would have been uniformed by annealing in the first place? I do not know enough to come up with an answer.

[GRUMPA]

I do a bunch of those, more like a lot actually. I can't really see the problem with that fuzzy picture but it looks like the case is buckling just below the shoulder. Which brings up a question of are those annealed prior to forming, which I hope it isn't.

Second: I had to make a smaller expander and do this in steps. My homemade expander has a more gradual taper to it to prevent the neck from splitting. I use it because when I expand the neck, I want the taper on the inside of the neck so when I ream them I take the taper out. After I ream them I install the factory expander and size them again, but they never buckle on me since annealing is the very last step.

ADDED: Maybe I should make a thread on that, there's a butt-load of details when converting those. Not only details but a swage press helps with that conversion. I have that expander I made smaller so when the neck is expanded, when the ram is raised it expands the neck, but only enough so the neck barely grazes the neck portion of the die. That's because I don't want the die making the neck smaller, I want the taper on the inside of the neck so when I ream I remove the taper.

[Rapier]

Old post, thank you for the data and tips..... have a few 308s to do for a 358 Win cast bullet rifle, I wanted a 358 Win for a while and just decided to build one, today. I have a few 35s now, but, wanted another. Like the spin or turnng idea.

[mdatlanta]

Old post, thank you for the data and tips..... have a few 308s to do for a 358 Win cast bullet rifle, I wanted a 358 Win for a while and just decided to build one, today. I have a few 35s now, but, wanted another. Like the spin or turnng idea.

Thanks for resurrecting this old thread. I need to convert some .308 brass to .358 WIN and this info has been helpful. ��

[Idaho Sharpshooter]

Interesting. I just FL size 308 commercial brass in my 358 FL sizer, prime, powder charge and seat a 250 gr cast NOE RN. I seat them to jam about .010" and fire them. Have yet to lose a case in 40 rounds. Need to get casting and PC'ing. Oh, yeah, I do use a homemade tapered expander die I made on my drill press.

Rich