Happy New Years to everyone here.

Yesterday, with some spare time on my hands I decided to see if I could successfully form a 7mm SAUM case from a 7mm WSM case, for my Remington short action 7mm SAUM rifle build. This came about because I had 20 Federal 7mm WSM cases that i haven't been able to get rid of, plus a bag of brand new Federal 300 WSM.

7mm SAUM headstamped brass is difficult to obtain, though 300 SAUM Norma is reasonably easy to obtain here in NZ, which I can then simply neck down. It is however expensive.

You are probably asking yourselves why don't I build a 7mm WSM?

Well, after doing alot of research into both the 7mm WSM & 7mm SAUM, I firmly believe that a 7mm SAUM is the better of the two for a short action Remington M700. Main reasons being in my opinion a better fit in a short action Remington M700 and I like the case for its efficiency and potential when chambered in a properly constructed rifle i.e. extended mag box and 24 inch barrel.

More importantly, 7mm WSM brass here in New Zealand is practically non existent, and will be for some time. Factory ammunition is quite easy to obtain, but its uneconomical to buy factory ammo for the brass.


A Couple of weeks ago, I found that a 7mm SAUM case head and a 7mm WSM case head are very close in diameter. I was surprised because all of the specifications I've seen for these 2 cases puts the SAUM case at .550 and the WSM case at .555, so I was always under the impression that the two cases were not interchangeable. However, measuring both cases with my digital vernier revealed that a brand new 7mm Nosler SAUM case measured .546 at the head and a brand new Federal 7mm WSM case measured .547 also at the head. This also applied to the Federal 300 WSM cases I miked.

So yesterday, I tried to resize a 7mm WSM case through my 7mm SAUM die. When you compare the two cases side by side, it is not difficult to see the difference in case length below the shoulder. However, this is only part of it. My 7mm and 300 WSM cases have a bigger diameter at the shoulder (.534) vs my Nosler SAUM case (.531)

I was under no illusion that this was going to take alot of effort to rework so, I lubed the case and shoulder with plenty of Dillon liquid case lube and waited for it to dry. I then ran my first case through my FL die...

...Disaster. I ended up with massive creases in the shoulder. After trying another 3 cases I ended up with the same issue, so I stopped and contemplated my solutions which were:

1. Anneal the shoulder area of the case
2. Change my case lube.

So, today before going to the effort of buying a blow torch to anneal, I decided to try sizing once more, but changing the lube for the case. I had no case forming wax, but decided to try car wax instead.

1. I gave the first 7mm WSM case a clean and polish to help it through the FL die.
2. Next I set my die up in my press as I would normally do when resizing (with the bottom of the die touching the shell holder). I removed the decapping rod assembly
3. Next I applied some wax to the case, but I ensured that there was no lube on the shoulder or neck, to prevent hydraulic denting (I think this is what caused the creases in the shoulder yesterday).

So with the case lubed with just enough wax, I ran it through the die. What I noticed is that there is a ALOT OF FORCE required to size that case shoulder down. To make it easier, I resized in several stages, and rotated the case several times inspecting it as I went, till the case was fully resized.

On closer inspection, I could see that while the case was perfectly formed, the shoulder was further forward than the Nosler 7mm SAUM case I was using as the control. I then wound my FL die down a full turn and ran the case through again and this time the shoulder was in the correct position.

After this, put the decapping and expander assembly back in the die and ran the case through again to properly resize the neck. Then I ran the case through my Lyman case trimmer to trim to the correct length.

These cases will then fireform in the chamber. It will be interesting to weigh the water capacity compared to my Norma 300 SAUM cases.

I can foresee doughnuts forming when I try this above process with the Federal 300 WSM cases.


While it may seem like a lot of effort, I was very happy with the result and it gives me another option should brass for my rifle become difficult to obtain.

However, I only intend to do this to use up my WSM cases, as I intend to buy 300 SAUM Norma cases.


Cheers,

Michael.

That's a lot of work Michael.

What you need is a mate who visits New Zealand a few times a year, bring you some SAUM cases.

quote:

Originally posted by Fjold:
That's a lot of work Michael.

Indeed it is, much more than is necessary.

First, don't over lube your cases, in fact, take great care NOT to get any lubrication on the shoulders -- just a modest amount on the neck and an ample amount on the body from the shoulder down. And clean the accumulated lube out of your FL die before resuming the process. I use Imperial Sizing Die wax these days, but if that is unavailable simply try automatic transmission fluid.

Next, don't use a 7mm SAUM case for comparison. Simply try chambering (after trimming to proper length) the reformed case. If it doesn't go, then turn your die down in small increments until it does. That way there will be no excessive headspace to deal with on the first firing. Of course, you'll need to chamfer both the inside and outside of the trimmed case mouths.

I have often made .25-06 & .280 Rem from .30-06; .243 from .308; .257 Roberts from 7x57; .256 Win from .357 Magnum; and even 6mm PPC from 7.62x39 brass. There are a few tricks to it, but it's not that much work and is well worth the effort when your desired caliber brass is unavailable.