.25 cal 131g .330G7 bullet from Blackjack Bullets for you to drool on ...

I'm sure a more experienced wild catter can chime in but that is basically it. I think some might advise to step it down in 2 steps if you're going 2 caliber sizes. Necking down can create a donut so you might consider going slightly smaller than .257 and then ironing it back to .257 with an expander mandrel.
 
maybe I missed it, but what is it looking like for these wildcat dies? Are they as easy as dropping a bushing and rolling on? I've got 284WIN bushing dies, so if it's just as easy as throwing in a smaller bushing to get 25-284, I may have to go that route. And I still have a couple boxes of 284 WIN lapua brass
I bought a 25-284 Redding FL die set from midway 2 months ago.
 

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maybe I missed it, but what is it looking like for these wildcat dies? Are they as easy as dropping a bushing and rolling on? I've got 284WIN bushing dies, so if it's just as easy as throwing in a smaller bushing to get 25-284, I may have to go that route. And I still have a couple boxes of 284 WIN lapua brass

Yessir you can just swap out the bushings as you need for your neck thickness and desired neck tension.

Some guys will want to order custom dies and eventually we will probably carry 25x47L and 25 Creedmoor to get them out to some gun shops, but we have had great accuracy and no issues just swapping bushings.

I personally size smaller first, and then use a mandrel to get back up to seating size. I have an old single stage I've used forever and one of the 21st Century pressure arbor presses and feel I get more consistent seating pressure using that method. 21st Century sells great mandrels and mandre-die-bodies if guys want to take a stab at trying that out.
 
Seems like I am reading mixed reviews on necking up vs necking down. I was planning on necking up 6 Creed via a .257 Carbide mandrel.

It's a fairly small jump, any thoughts or concerns?
 
Seems like I am reading mixed reviews on necking up vs necking down. I was planning on necking up 6 Creed via a .257 Carbide mandrel.

It's a fairly small jump, any thoughts or concerns?

I've done my 6x47 brass on 21st Century mandrels no problem. I only have the TiN coated ones but the bare ones probably work just as well.

If you haven't been on the 21st Century page before notice they have two options for mandrels #1- Turning Mandrels for their neck turning lathe and #2 Expander Mandrels.

http://www.xxicsi.com/expander-die-body.html
http://www.xxicsi.com/arbors-and-mandrels.html
 
I was worried about donuts necking down but that is probably negligible given the small jump? Looking for experience and best practices with necking up vs down.
 
I was worried about donuts necking down but that is probably negligible given the small jump? Looking for experience and best practices with necking up vs down.
I neck down .270 Win brass for my .25-06 AI in 1 step, and have no issues with donuts. First I FL resize the .270 Win brass in a .270 Win FL die, then I run them through the .25-06 AI FL sizing die. No issues here.

However, I wouldn't try to neck down more than 2 caliber sizes without an in between step, just to be sure to avoid donuts. But 2 sizes should not be an issue. And going from .264" (6.5mm) to .257" is such a small step (only a 0.007") that unless something is severely wrong, it should not cause any donuts or problems with necking them down.
 
I was worried about donuts necking down but that is probably negligible given the small jump? Looking for experience and best practices with necking up vs down.
I ran 100 brand new 6.5x284 Lapua brass through my 25-284 die. No donuts. .257 and .264 are so close together I don't think you'll ever get a donut
 
Ran a little test on some 6xc brass taking it to 6.5 with only a Sinclair expander mandrel. Lubed neck and mandrel. Checked run out before necking up. Ran smooth, and run out did not change. The case did shorten about .0045", but I'm thinking a brand new case will be even smoother, and really not worried about that shortening affect, not to mention .257 will be an even smaller jump up.
 
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