Fireform .375 RUM brass for .338 Edge?

[oltmann]

I just picked up some .375 RUM brass to size and use in my .338-300 (Edge). Before and after I size the brass in my press, the shoulder is around .020 to .024 shorter than my fired brass. I used a Hornady/Stoney Point cartridge headspace bushing gauge to measure.

This is the first time I have checked the headspace of a sized and unfired brass. The reason I am being careful now is I recently switched from Nosler 300 Ultra brass to the Rem 300 brass. On the 3rd firing of the remington I had a cartridge base seperate, and others getting thin in the same spot(about 1/2" up from base).

My first thought was that I had undersized the brass(since I am using a .338 ultra die, it is possible if I wasn't paying attention) I bought the gauge tonight to check the size of the rest of the unfired brass from the group where I had the brass seperate. They were either the same size or less than the fired brass by .003"

Now I am wondering if the 300 ultra remington brass was similarly short for the chamber on initial forming as I am now seeing with the 375 brass. It would explain the case seperation, which should only happen with excessive headspace.

Another note, the fired brass is .001 shorter than the Go Gauge I used to set the headspace on the rifle(Savage 110, PacNor prefit barrel) I also checked headspace on the rifle and it is fine. As well as the fired Nosler brass is the same dimensions as the fired Remington, so headspace hasn't changed.

Long story short. It looks like I'm going to be fireforming for my 338 edge. Does anyone else have this problem? Or any ideas what I could be missing?

thanks in advance guys.

 

[6.5x300]

Recently formed several .338 edge brass from .375 RUM brass. I also have a Pac-Nor 30" straight tube on a savage 110. I would first run new brass through a .375 RUM die to straiten up any dents in bass. Than I would neck it down alittle at a time using a .338 RUM die. I would use my chamber as a guide. Starting out with brass that would not allow me to close the bolt because I had not set the shoulder back enough. Then continuing to adjust the die till it sized the new brass just enough to close the bolt. Once I found this setting I tighten the set screw on the die. It should now be set for your individual chamber. It would seem that since we are necking down brass, any problems with new brass have to short of a shoulder would be solved by the false shoulder we create. I certainly don't claim to be an expert, there are many here that are. This is just what worked for me. Hope it helps. Good to see fellow shooters out here in the Pacific Northwest.

 

[royinidaho]

6.5 describes it well.

Some, me for one, when using a die for the particular cartridge slip a small shim (~0.1") under the die nut. The nut is set for proper FL sizing. Thus a small over ring is remains ahead of the shoulder to ensure the case is firmly supported at both ends when fire forming.

For me is was a bear to get the die set up for a proper FL resize and not push the shoulder back a schosie bit too far.

Once set up, all that is needed is to insert the shim for the new brass.

 

[oltmann]

Thanks for the replies guys.

6.5, the method you describe would be settig the headspace on the neck side of the shoulder, while I was thinkng of it in terms of the body side of the shoulder. I will give this a try tonight after work. Seems like a good plan to keep from needing to fireform. I'll still have to fireform the ones I have already sized.

Roy, that's a good tip for fire forming. I'm hoping to use a similar method with full power loads now that I am thinking of the headspace more correctly.

 

[davewilson]

Roy, a .1" shim seems awful thick to me, do you mean .01?

the main thing i see that you need to do is check the diameter of your neck on a loaded round. they just might, make that probably will be too thick or tight in your chamber. you're going from 375 down to 338 so the neck walls will be getting thicker. something you should check before touching one off.

 

[oltmann]

Dave, thanks for the feedback. I do plan to turn the necks on the 375 before I fire them. I failed to mention that before.

Right now I'm most concerned with the apparent excess headspace problem I had seen with some of my 300 brass, and making sure I did not repeat the same error with this new set of brass.

 

[oltmann]

Update. I just finished sizing to the minimum headspace on the neck side of the brass and I am confident that they are accurately headspaced. Problem solved(hopefully)

The shoulder is a fairly funny shape compared to the shape of the fired brasss and chamber. Will full power loads still be fine for the initial loading of this brass?

 

[Pdvdh]

I wouldn't go with full power loads. Others may feel differently. If you're blowing the shoulder forward and outward, I would use a reduced load. If you get any shoulder or neck splitting, you'll have to anneal the cases prior to fireforming. I incurred this problem when fireforming RWS 404 Jeffery brass to the 338 Edge.

It wouldn't be a bad idea to anneal the case shoulder/neck prior to fireforming if you're comfortable doing that. That should prevent any case splitting and by the time you've necked down and fireformed the brass, it would be a good idea to anneal it anyhow.

I had to get knowledgable and comfortable with annealing since the 404 Jeffery RWS brass was $2.50 a piece at that time (3-4 years ago) and I couldn't afford to keep losing cases due to splits at the shoulder/body junction.

You could even fireform with cornmeal at this point since you're headspacing off of the enlarged neck. This would save you some bullets and wear and tear on your barrel.

 

[RockyMtnMT]

When you turn the necks down, how thick or thin should the neck be? I am having the same problem sizing down 338 to 308. The sized brass will chamber, but when I seat a bullet the neck is too thick to chamber the round.

Sorry to hijack the thread, but it seemed to be a good place to ask.

Thanks, Steve

 

[oltmann]

The shoulder is pretty close dimensionally to where it needs to be. Just has a funny shape because of the 'double shoulder'. Right now I'm thinking of doing a ladder load up towards a moderate load and see how that goes. After neck turning of course.

Also, I know what you mean about brass cost. When I first paid over $1 for nosler I thought it would be nice enough to be worth the cost. Now that I've switched to Rem late in the game it's up to almost $1 a brass, when you can find it.

Steve, good question. Not that off topic at all. I was just going to start researching that next.

 

[KRP]

When you turn the necks down, how thick or thin should the neck be? I am having the same problem sizing down 338 to 308. The sized brass will chamber, but when I seat a bullet the neck is too thick to chamber the round.

Sorry to hijack the thread, but it seemed to be a good place to ask.

Thanks, Steve

How thick you make them depends on how much clearance you want between the neck and the chamber. Some BR guys use .001" clearance(and some don't need to resize necks after firing). .003-.004" would allow a little more room to prevent problems from unforseen circumstances. Factory chambers are usually cut with even more clearance. The less clearance the less the brass is worked during firing, but you need enough to allow proper release of the bullet.

 

[6.5x300]

Glad it seems to have worked out. The slightly rounded look of the shoulder will sharpen up once fired. Check previous posts reguarding need to fireform brass after necking up or down to form edge brass. It seems most replys were that it made no difference in acuracy with the edge. Dave made good point with checking neck thickness. All mine have been OK so far all though I plan on neck turning them when I acquire the right tools. As far as reduced load...probably good idea, though the few I have shot I loaded the same, and again others have commented in previous posts as well. 300gr smk and H1000 with CCI 250 primers standerd load. I have not shot the new formed brass over the crony yet, or even compaired accuracy between REM and Nosler. Will be doing so soon and post results. I would also check the potential diference in case capacity between the 2. As I have found the rem to weigh a little more than the nosler.
Good shooting,

Brian

 

[Pdvdh]

I would outside neck turn for 0.002-0.003" total clearance, if possible. So if your chamber neck measured 0.337" in outer diameter, I'd outside neck turn so that a loaded cartridge neck measured 0.334 to 0.335" in diameter. A tighter tolerance can help reduce case neck and bullet runout. The less you work the case neck the longer the case neck life. Also, with the cartridge loaded in your chamber, the bullet may be held in better alignment with the centerline of the bore since the neck will be held within a tighter tolerance within the chamber.

With a factory barrel, you'll probably have plenty of clearance without outside neck turning. With a custom barrel and chamber, you may need to outside neck turn to obtain proper clearance... it will just depend on your chamber dimensions.

 

[Lost creek]

I have 100 338 edge cases made from 375 rum brass. I used a full power load of 94grs. of h1000 with a 300 smk the first time i fired them with no problems at all. Your not really firefoming just getting brass to fit your chamber like every other gun you shoot new brass in. My loaded neck diameter is .366 and my chamber is.369,i did not need to neck turn.