Forming brass for 300 AAC

[motoduck]

I have only been reloading for a couple of years, mostly pistol and some 223/5.56 for the ARs. I am buying a 300 AAC upper and want to start reloading for it as well.
I am confused about the process of forming 300 AAC brass from 223/5.56 brass. I am looking at a set of Forster dies (full length sizing, Seating). Will these dies expand the case neck from a .22 to a .30? Or, do I need to purchase a seperate case neck expander, expand the neck then size and trim the cases?

[Stormrider]

None of the above.
The 300 case is substantially shorter than the 223 so you have to trim it down to just above the body/shoulder junction.
If you use the 221 Fireball case you just expand it in two steps using a good lube, (tapered expanders are supplied with the die set) and your good to go.

But with new and already trimmed and sized 223 brass available, why would you want to go to all the trouble?

[motoduck]

Stormrider,
Thanks for responding. I assume by this quote you are saying 300 AAC brass is available to purchase? I have not been able to find any brass and only limited amounts of factory loaded ammo. Am I missing the boat on a source?

But with new and already trimmed and sized 223 brass available, why would you want to go to all the trouble?

As for reloading and reforming brass. I do not have any 221 fireball brass but I have tens of thousands of 223/556 cases, that is why I was headed that direction. I am still confused by the "reforming" process. I use a Giraud trimmer. When reloading 223/556, I size my cases then trim, then reload. Are you saying I have to "rough" trim the cases, resize and then "retrim" them so they are the correct size?

Tapered expanders are supplied with the Forster dies and I can expand the case necks of 223/556 brass (not 221 fireball) with out purcasing additional neck expander?

[motoduck]

I did finally see the post about CMMG selling primed brass. I will buy some of this but I still want to roll some of my own.

[Stormrider]

Didn't realize you were going to use a power trimmer. My comment was referenced to trimming one case at a time. (ugh!) Power trimmers are great.

I have never used a Giraud trimmer but have heard good things about them. I believe, from what I've read, that they space off the shoulder of the case, so I think you would need to resize first without the expander ball in the die and then trim. After it's trimmed the mouth of the case will fit over the expander ball in the sizing die, especially if it is tapered.

Since you have a lot of 223/5.56 brass, I agree that that is the cheapest way to get 300 BO brass. It's the way I got my 300/221 Fireball brass using a Dillon Rapidtrim.

[Matt-man]

The .300 BLK case is so much shorter than the .223 that the case mouth on the .300 BLK is below where the shoulder is on a .223. As I understand it, the forming process is to run the .223 brass into a .300 BLK sizing die without the expander ball. This creates a new shoulder and a .30 case mouth way down into the .223 case body. Then trim to length (roughly 1.400", I don't have the exact .300 BLK specs). You end up trimming off the .223 case down below the original .223 shoulder.

Here's some info on forming .300-221/.300 Whisper which illustrates the process: http://www.ar15barrels.com/prod/300-221.shtml

One problem I see with trimming these on a Giraud is the V-shaped cutter that the Giraud uses. You generally set up the cutter for a particular case mouth diameter. Since you have to cut all the way down through the original .223 shoulder, there's no single diameter that you can use to set up the cutter. This isn't something I've actually tried, just thought about, so maybe Doug Giraud has a solution for this particular problem.

[Stormrider]

...You generally set up the cutter for a particular case mouth diameter... maybe Doug Giraud has a solution for this particular problem.

If he doesn't have a solution for it then you can take a coping saw or hacksaw blade and cut the case roughly to length in the forming die and then trim it with the Giraud.

Stormrider,
...Are you saying I have to "rough" trim the cases, resize and then "retrim" them so they are the correct size?

Not exactly, but you will have to form with the form die, rough trim and retrim with the Giraud and then run them through the sizer die. So you'll need three dies. A form/trim die, a sizer die and a seating die.

Good luck with it.

[motoduck]

Thanks for the insight. I have a better general understanding at this point. I can see this is going to be one of those things that becomes clear (and I hope simple?) once you do it a few times.

[Stormrider]

It'll be tedious... I've done it more than a few times... Which is why I got the trim die for the Dillon.

[TommyG]

Discussion and photos of the process at this site:

http://www.bradswarehouse.com/

Click on the Services tab he also talks about Giraud trimming the brass.

I was curious about the process too. The photos at the bottom of the main page give a simple view of how he is forming then trimming the brass.