Now that idea I like! Thanks! Will it make any difference to case capacity? Would my 7mm dies be O.K. to directly size the 300 case with, or is there some intermediate step that I should take?

Brand new Encore barrel, never been fired, ordered direct from the factory.

A common recommendation for case forming is to take a fast burning powder like Red Dot, Bullseye, etc., see how much it takes to fill the case completely, and load about 20% of that. Fill the rest of the case with something like grits or Cream of Wheat. (Dry.) Leave enough room for a little wad of tissue or something to keep it all in the case till fired. Aim it in a safe direction, as even blanks can do a lot of damage up close. I'd lightly lube the cases so they can slide back in the chamber and expand mainly at the shoulder, rather than binding in the chamber and stretching the brass right ahead of the case web.

The more important question is, why are your cases short in the chamber? Have you compared their measurements with a case drawing for the cartridge to see if they're out of spec? Could your barrel be chambered too deeply? Is this a new barrel? It's not a used one that could've been rechambered to some "improved" cartridge, is it?

Worriedman,

First trim the 300 WM brass back to about 2.5" with a .30 pilot and then chamfer the necks well inside and out.

Then just run the case into a 7mm RM FL die.

Trim again to 2.490" and your ready to load.

Don't worry about case capacity.

If you want to size DOWN, an even better idea is to use 358 Norma Mag brass. It's .040" longer in the body and you can set the shoulder back to EXACTLY what you want. Not likely you'd have to worry about the necks thickening either, it would likely not be over a thou and those sloppy necks can easily handle that. Not trimming, no neck turning, and no donuts in the neck down the road, and you have better brass to start.

I have a T/C Encore in 7mm. New brass (R/P), neck sized only seats below the end of the chamber. The chamber to frame gap is .005. so I figure that I should size the brass to seat .004 out from the end of the chamber. What bullet/powder combination is correct to blow the shoulder forward?

I do appreciated the info. Will get that started this afternoon, if I can locate some brass in Memphis!

Showing my ignorance here, but; forming a"false" shoulder by necking up, I would suppose you mean expand the case neck, then neck size it back to correct diameter for 7mm and leave the .30 dimension at the shoulder to hold the case in place to fire form?? Load a light load or standard, and would it be best to seat the bullet out to the rifling?