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.

[chadbag]

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.

How did you use the Dillon Rapid Trim for this? The smallest case you can do is about 223 on it. They have a separate trimmer system for 6.8SPC and 7.62x39 due to this.

TIA

[Polymerhead]

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?

I just wanted to bump this with some more info, since there is so much buzz about the 300 blk and not a ton of specific info. You can't form brass from 221 fireball with a Forster die set. I bought a set the other day with some 221 Fireball brass since it was in stock. It's a no-go.

Before someone yells "duh!" my theory wasn't completely off base. Some sets like the Redding die set have multi-step tapered expanders that work for the up-necking. The Forster set has a ball-type expander that isn't tapered enough for this.

The Forster set seems to be very good quality and I will keep it and just wait for some 300 AAC brass I suppose, unless I get bored and buy a cutoff saw and go to work on some of my 223 Rem brass.

Hope it helps.

[BradL45]

Midway is showing that Remington brass will be in stock on July 15th, and Back orders are OK, I would guess that it will sell out quick unless a large amount gets to Midway. I already have my order in. It's about $25 per 100(plus shipping so order lots of bullets at the same time) and it's primed, which is cheap for factory Brass.

I've loaded ammo on both the Forster Dies, and the Redding dies, they both make good ammo.

Soon 300 Blackout trim dies for the Dillon RT trimmer will be for sale, it one of the quickest ways to convert 5.56 brass to 300 BLK.

[m4fun]

Tagging for future ref.

Great thread on a caliber I may be very interested in!