Hubel 458: Ed; a lot of water has gone under the bridge since this post started. I wasn't able to send cases to MBundy as the US put a prohibition in place preventing mailing cases across the line between individuals.

The brass sat around for a few months and I measured a whole lot of them. I came to the conclusion that the chamber they were fired in didn't come close to resembling the 7 x 61 S&H reamers as used by Schultz and Larsen.

I ordered up a set of RCBS case forming dies and set to making a bunch from 338 and 300 Win Mag cases. Surprise , these wouldn't chamber either. I ground .020 off the shell holder and could squeeze WW brass in and out of the chamber but that was all- R-P and Fed. brass would not size down enough for even a forced chambering.

A query to RCBS revealed that several forms of this case exist. The original case used brass that had a slightly larger rim than standard H & H based brass. Only a very small amount but enough to require different shell holders for the original case.

My take on it is that the cartridge never really took off as a commercial product (no major U.S. maker chambering). Subsequently, chambering reamers were developed for gunsmith use in N.A. and the reamers were developed around standard magnum brass and a bit of modification to the body taper probably also occured. Similar but different.

One hunter told me he was simply able to shorten 264 brass and run it through his F.L. die and it chambered in his gunsmith barreled rifle. I tried it and the bolt still had nearly an inch of travel when it was as far in the chamber as it would go.

In the end I returned sizing dies and case forming dies along with some once fired brass to RCBS through the services of a local dealer. RCBS reworked the dies to match the cases and I'm forming good brass like mad now. RCBS made the changes as a free warranty service and that was pretty darn nice of them.

During the measuring process of the gift brass I found three cases that were so swollen at the head including the rim that they would no longer slip into a #26 shell holder. These cases all had factory marked Norma primers in them so I believe them to have been factory loads.

I came to the conclusion that the chamber of the rifle they had been fired in must have been oversize in diameter regardless of what brass may have been used. I sectioned several cases and none showed any sign of incipient case separation line but if the whole lot had been done some might have. Perhaps a single firing won't produce that effect if the chamber is not cut overly long.

They are history now as the whole lot got dumped off a high bridge into a big river. I couldn't bring myself to passing them off at some gun show like the other guy did.

Used the rifle this fall to take a big bull moose and the animal literally fell in his tracks. It's a good cartridge in many respects but later developments (7 RemMag)put the skids under it as buyers wanted the domestic product. Despite being a bit smaller in capacity it's ballistic performance is very similar to the Rem Mag. My hunting load puts a 160 grain Game King out the spout at 3025 fps. Max loads will exceed 3100 but cases are stretching at that point and bolt lift is getting a bit stiff.

best

Michael-Glad you got it solved.With bases expanded
that much you were right in getting rid of them, or you would have had to rechamber with a special oversize reamer.The tool that they were talking about on this thread will work for a small amount
of expansion, but if used on some of the cases you described, the corners would be kinked and
weakened.The funny thing is they could still have been used in the rifle that made them that way,
as they were made to fit by firing, as long as
resizing die used fit the odd size operation,and
the primers stayed in.Do you use slow ball powder?
If not try some, it will make cases last longer.
And with right one you can still get 3000fps. Ed
Hubel.