Practices for necking down brass.

[shawnb]

So I haven't been able to find good info on necking down brass. My project is necking down a 300 win to 7mm. But any advice from anybody on any wildcats is good.
What are the easiest ways to do this 7-300 wildcat forming new brass. The supplies I have is a 7mm rem mag FL sizer, bushing neck sizer and competition bullet seated.
Can I run then in the FL sizer in one shot? Use diff bushings to step it down, do I neck turn after?

 

[Mikecr]

24thou in one move.. I don't know..
It would take several bushings to do this without collapsing of the necks smaller than desired.
I think you'll get into trial & error on it.

You may need to bring it down some with bushings and final size with the FL die.

I would turn where it fits the mandrel best, and that's likely while at 30cal. As the brass gets thicker with downsizing it's growing springback makes mandrel fit a real battle.
Again, trial & error.

 

[Rocky Mountain]

I've done it 30cal to 7mm in on step down, just use a 7mm neck die the same in the body as the 30cal parent case

 

[Nimrod]

I neck .308 brass down to .270 for my .270/08 improved in 2 steps, I use a 7/08 die as the intermediate step. I'm thinking it will probably work , try it and see! I don't turn necks unless I absolutely can't avoid it so can offer no help there.

Bob

 

[shawnb]

Thanks for the replies. So when you you stepped down with the neck die what size of bushing did you use? My chamber will have a standard .316 neck so I'm thinking around .314-.313 will work fine?

 

[shawnb]

I just talked to a few smiths and they said I shouldn't go this route. They warned against the necks being to short to hold the bullets properly. Have you guys had any troubles with this?

 

[Edd]

The necks will be about .250" long. That will be slightly shorter than a 7mm Remington Mag and I've always thought they were too short.

 

[rmorgan9718]

I agree that the necks are probably too short. another point: I am loading 6x284 for son's friend, and forming the brass is a bitch in one or even two steps. I finally got tired of ruining every 5th round or so, and order case forming die from RCBS. Was lucky, they were running another one the next week, and simply doubled the run. got it in two weeks. Works great, but use lots of Imperial Sizing wax.

Redding also makes these case forming dies, but their delivery was out to 8 weeks.

 

[BSF350]

Will this brass be fire formed after necking down?

I just squeezed some 8x57 to 6x57 with three necking dies (30cal, 25 cal and 243). I plan on forming the brass in a custom chamber, Is this a wrong approch?

BS

 

[rmorgan9718]

my plan is to fire-form them using squib loads with older no-longer used bullets. I have no experience with this caliber and this is the tried-and-true method I have used with other necked down brass loads.

Thoughts anyone?

 

[cfvickers]

So I haven't been able to find good info on necking down brass. My project is necking down a 300 win to 7mm. But any advice from anybody on any wildcats is good.
What are the easiest ways to do this 7-300 wildcat forming new brass. The supplies I have is a 7mm rem mag FL sizer, bushing neck sizer and competition bullet seated.
Can I run then in the FL sizer in one shot? Use diff bushings to step it down, do I neck turn after?

Make sure your cases are well lubed and just run one pass through your FL die, I do it all the time necking down 308 to 7-08. I am quite sure you won't collapse anything. Don't try it in the neck die or you will, the case will need the support offered by the full length die. If it is too tight the first try get you some hornady wonder lube or whatever the new stuff is that comes in a tub. I have a tub but am not looking at it. That stuff will make brass slicker than snot and it makes necking down cases a breeze. I have necked down 284 brass to 6mm 284 in one pass, but it required forming where if I ran it through my 6.5-284 die first it looked like it was straight from the factory. I wouldn't sweat it. nickel cases don't neck down as easily. As far as neck length goes, use once fired remingto or winchester brass, it would need to be trimmed a lot after the first firing in 300 win mag. Most of my remington cases run .0015 over max after the first firing and new they are at max. New Win cases are usually the same, but without trimming I cannot make remington cases fit in my 700 in 300 Win. Mag after one firing. Bolt will not close at all because the case is just too long.

 

[Gene]

I think the Hornady "stuff in a tub" is called Unique. I have been using it for two years now, and love it. Cheaper and better than Imperial.