Is factory brass available for the .300 whisper?  I'm looking for a caliber that will have decent energy when run subsonic through a can.   Further I need it work well with .223 magazines so the 6.8 is out.   As far as I can find, the 300 whisper or 300/221 is gonna be it.   I dont want to destroy half my brass forming it out of other cases,  I'd rather buy in bulk and help avoid mixing up the brass with .223 stuff.

Sorry, not available.  You can either but preformed brass directly from JD Jones (SSK) for like $17 for 100 pieces, or form your own.  SSK's brass is once fired Lake City;  CorBon loads a couple 300 Whisper loads and they also use fired Lake City brass.  
If you want something easily distinguishable from .223 brass, buy Remington brand .221 Fireball brass and neck it up to .30.  Use this exclusively with the whisper.  
-JD

www.sskindustries.com/

edited for spelling

I just ordered1000 brass for $120 shipped. It is supposed to be made from once fired commercial 223 brass from a police shooting range. I would let you know the quality of it once it comes in and who it is from.  I also want to say that I shoot the 300 whisper and like it so much that I am building another 3w ar as we type. The one I have know  will be stickly can use.(sighted in with 220gr subsonic 1/8 twist pistol lenght gas system). The new one will be for feral hog hunting(125gr sonic close to 2400 fps carbine gas system 1/10 twist). I like the 30 cal ar set up. Every thing is stander ar 15 parts except the barrel cal and gas tube if pistol lenght. The only draw back is that it is not a walmart calibre and you got to reload if you like to shoot often. After this one is finish I will do a 3w pistol with my can attached.The pistol will be built on the cheap.

I'm waiting on a barrel. But I need to get going on an upper and bolt for it.  I'm building mine on a ajustable gas system.  KISS type rifel.  Red dot and BUIS to be used for pigs.

It's very easy to form yourself from .223.  Click here to go to the FAQ.  My process can be easily streamlined, wether you're going with the .221 Fireball or the .223 Rem method.

SSK and AR15barrels.com both sell pre formed brass.  Also keep an eye out on the EE.  There's a guy that routinely has brass for sale.

Tom  

We are in the process of introducing the 300 Whisper to SAAMI for approval.  The whole process takes close to a year.  After it's accepted by SAAMI, brass should be readily available from folks like Starline.

Quoted: We are in the process of introducing the 300 Whisper to SAAMI for approval.  The whole process takes close to a year.  After it's accepted by SAAMI, brass should be readily available from folks like Starline.

That would be great, frankly the brass forming process is far too involved for me to consider running this caliber for now.   I think it would gain wider acceptance if it was easier to obtain/load.  Factory brass at reasonable cost would be a huge step.  

Question for you:
Almost all the reloading data that I can find calls out for a 1.400" trim to length, yet some Corbon cases that I measured today are 1.355".
So, which is the right trim to length?
Thanks,
Gos.

Quoted: We are in the process of introducing the 300 Whisper to SAAMI for approval.  The whole process takes close to a year.  After it's accepted by SAAMI, brass should be readily available from folks like Starline.

The original design for the 300 Whisper used a .221 Fireball case necked up to 30 caliber.  That's what we use here.  When you form cases from .223 cases you can trim them to 1.4.  The .221 Fireball case is less than 1.4 to begin with, then when you reform it, you lose even a little more length.

Quoted: The original design for the 300 Whisper used a .221 Fireball case necked up to 30 caliber.  That's what we use here.

My Cor-Bon ammo uses Lake City cases; was SSK providing you with formed cases before?
-JD

If you answered it I missed it.
So, what is the trim to length for the standard 300whisper?
Thanks,
Gos

I'm not sure why the load info you have says 1.4 as a trim length.  Can you let me know where you got that data?  The length of 1.355 is what the load was originally developed at.  That's  the length of the brass we use.  JD would have a more clear explanation on this question I'm sure.

My older Sierra pistol manual (50th anni~) stated the trim-to-length was 1.390".   Then it had a dimensioned cartridge next to it showing the overall case length of 1.400".

After speaking with Sierra, they admitted this was an error, and that both should be 1.355".
Also, the maximum case length should be 1.365"
I also called JD Joned and confirmed this.
-JD

That's what I was looking for.
Thanks folks,
Gos

Quoted: We are in the process of introducing the 300 Whisper to SAAMI for approval.  The whole process takes close to a year.  After it's accepted by SAAMI, brass should be readily available from folks like Starline.

1 more year to wait