6.5-300 Weatherby Brass??

[Overdrive]

I recently purchase a 6.5-300 Wthby and was lucky enough to pick up some factory ammo (3 boxes) from the salesman that had some before changing his mind on the caliber. My question is has any one had luck down sizing 300 Wthby brass to the 6.5? I also have a 300 Wthby so I have a lot of brass around. Any tips on resizing the 300 Wthby brass or things to watch out for, seems to me it could cause a really weak spot where the neck and shoulder meet. Any help is appreciated.
And I'm also looking at doing handloads with Scirocco 130gr with Retumbo or H1000 since it will be a long range hunting rifle I want the temp stable powders. Any one have a good load worked up. I'm thinking I should be able to push the 130 Scirocco's 3400fps.

 

[Cahunter805]

You would need a bushing die or mandrel set and have to size the 300WBY brass down in a few different sizes. Going from 300 to 6.5 in one step wouldn’t be advisable.

 

[wind gypsy]

I'm not familiar enough with the cartridge to know if a 6.5x300 is dimensionally the same as the 300 weatherby everywhere but in the neck. If it is, and you have a 300 Weatherby bushing die, its just a matter of buying bushings in steps that would get the inside of the neck to less than .264".

Some things to keep in mind:

1. The more you size it down in each step, the more opportunity to wreck your brass or induce runout. I've only necked down from 7mm to 6.5mm but tried to keep my sizing steps less than 0.010" each. Even then, you might find that your sized cases have more runout than you'd like and prefer them after being straightened out from a firing.
2. By sizing down that much you are going to thicken the necks quite a bit and you'll likely need to neck turn to get the right neck thickness unless you have a bunch of neck clearance in your chamber
3. Necking down that much is working the brass a lot, you'll likely want to anneal afterwards