Dumb things I just didn't think about.

[Harter66]

I aquired a 264 WM that doesn't appear to have been fired. With "the standards " being still thin and the exotic being hit and miss at best,the thing to do is just make some brass ....... A mag case is a mag case except for 450.....right?

I just gave no thought to a 300 WM case growing a full 10th of an inch in stepping it down to 264. Maybe it is because of all the sloppy GI guns I've had or the NATO over 308 or even the 8x57 from 06'. Even the 280 AI from 06' wasn't a big deal but the 264 from 300 via 275 H&H grew a 10th .I knew that the H&H taper might be an issue but with the shoulder push it all looked good but the bolt just won't close on that long neck. Now if I had a universal neck die with inserts and being able to knock it down to 25 and COW form them back,yep that'd be nice.
Off to the trimmer,while I wait quietly for the 258-120 NOE to run and take measures for the Buckshot dies.

[Mk42gunner]

Just thinking out loud here, but I think it would be a lot easier to neck down 7mm Remington Mags than to push the shoulder back on the .300 Winchesters'. Unless you already have a large supply of unneeded .300's that is.

Robert

[Harter66]

The WMs are mostly all 2.5 inch cases to fit standard actions. The 7 and the Weatherbys are a lot longer. The 7mm RM to 264 would be like 6mm Rem from 270 or 280 or 260 Rem from 7x57. I didn't expect to grow the neck that far . I guess I should have after having made a few 7x57 from 8x57.

[paul h]

The 300 win mag case didn't stretch 0.10" when necking it down, the 300 win mag case started 2.6" long. The .264, .338 and .458 win mags are 2.5" long, the 300 is 2.6" long, and has it's shoulder in a different spot than the .264 and .338.

As mentioned, the 7 rem mag is a better starting point.

[Leslie Sapp]

7mm mag brass is the easiest, just run it through the 264 sizing die once and you're good to go. When we got my daughter's .264, we had no 264 brass, but I had a lot of Remington 7mm mag brass. We ran it through the die and tried it and it shoots so well we're still using it instead of the 264 brass I bought later.