Forming 338-06 brass: What parent case do you use?

Historically forming the 338-06 is an easy process, just run a 30-06 Govt case into a tapered expander 338-06 sizing die, load, and shoot. What most articles/reloaders don't tell you is that the cases come up a few thousandths short. I've heard that using a 270 Win or better yet a 35 Whelen case will give you resized cases of the correct length after minor trimming.

For those who are shooting the 338-06 (A-Square per SAAMI) what are you using to form cases. Of course, the simple answer is to avoid the whole process and just buy 338-06 factory cases...except for the component shortage and the fact that the 338-06 is only moderately popular makes that hard to do.

Any experience offered will be appreciated,

Thanks,

Paul

270 is a good candidate as it is a little longer than 30-06. Have you tried reforming 270?

If it's named "something ought six"; you should be able to make cases from the namesake, right? 25-06 from 30-06 works fine. The short cases will delay case trimming....[emoji16]

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Yes. I have used 270 Win. cases and they work out best. Neck them up in stages or using a step expander. The extra length as a 270 works out well - trim to the correct length right off the bat. I've made plenty from 30-06 and they are fine enough but the 270 is the way to go if you have the brass.

Whelen marked brass is not common and worth enough that you can sell it, buy 270 and come out ahead - in normal times. These days, ???? you may have to go with what you can get.

The 338-06 is a neat cridder. It was my go to rifle in the late 1970's and 80's here in Colorado. A very sensible cartridge.

I have been doing the 338-06 for years and love it , I did form it from 30-06 in the beginning and quickly noticed with out annealing that I got very poor case life. a bit of experimenting showed that I have better results forming down than up, So I form it from 35 Whelen with very good results. R-P brass is the only brand of brass that I have been able to get hold of in 35 Whelen

I sold mine quite a while ago, but made mine from 280 Remington brass - mostly because I have a 270 and it made brass sorting simpler. But I think that the 280 is a bit longer than the 270 anyway.

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.338-06 AI ,Winchester brass fire formed has worked very well for me in my rifles. I did buy a bunch of Nosler .338-06 brass when it was around other than a proper head stamp it’s not better.

I learned two things very eatly on with the .338-06: (1) simply necking up an 06 case and fireforming is a mistake and (2) starting with .35 Whelen brass saves time and maybe money.
I started with commercial 06 brass, nicking up and fireforming and came close to case head separation due to excess headspace on the case. Doing some research I hit upon the idea of nicking up to .35 then back down to .338, leaving a step at base of the neck. Sizing the neck back to .338 a little at a time until the bolt would close with a bit of effort, trapping the case between the chamber and bolt face. At this point the case was fireformed with perfect headspace. Starting with .35 Whelen brass eliminates the work involved in necking up to .35 and eliminates that much working of the brass.

Having shared the above I should share some further experience with this cartridge.
You can decide if it matters. With cases formed from commonly available US commercial brass, in my rifle,, any load approaching full power but with normal pressure signs displayed a pronounced step in the case wall at the start of solid case web. This lead me to wonder if the chamber had been cut properly or maybe wallowaed out. The situation also lead to discovering how undersized US made brass is. I found some to be as small as .464" just ahead of the extractor groove; this diameter on cases intended for chambers cut for cases spec'd at .470". I no longer have a rifle chambered for .338-06 but this case vs chamber diameter situation made me uncomfortable with ever pursuing the upper safe limits of performance with this cartridge. More recently I learned that the chamber in question had in fact been cut exactly to spec.
I believe the. 338-06 is a great cartridge but based on the above I recommend caution in choosing brass. I am not sure about all bbrass currently available in the US but do know R-P, Win and Hornady are small while PPU mics right at .468". I would now investigate the dia of Lspua brass and be willing to spend the bucks just for peCe of mind.
Before I knew about PPU brass the best fitting cases I ever formed were made from 9.3x62mm brass tho with a too-short neck.

Hope this is of some benefit.
DH