Les, JD Jones has created a complete line of “Whisper” rifle cartridges. (gelan has a 300 Whisper)
The 300 is a 221 Fireball case necked up to 30 caliber and uses standard 30 cal bullets.

Here's a link that gives some info on the Whispers.
www.300whisper.com/sskwhisper.html

Dimitri wrote:

Which reminds me, I have been told a good way to keep the powder down up against the primer is to add some cotton off a cotton ball to fill up the extra space. Dimitri

This is true but, the cotton can interfer with gas expansion and that could be bad !!!

Know what your doing before you do it !!!

Chambered, you make a point about it interfering with gas expansion, but as it was explained to me the cotton gets burnt up from the primers ignition alone, and combined with the burning powder, it should play little to no value in chamber pressures.

However as I said I only been told about this never tried it myself.

Dimitri

I'll try and find the info I had !!!

I can not find the notes I took when I was considering doing this myself for light loads in the .44 mag.

I do recall the subject was centered on the type of fill to be used in regards to its density and how much was used.
Powder migration was the issue I was alluding to in the above post.
If the powder was to move around and separate into smaller pockets surrounded by the fill proper ignition could be an issue.

Please research the subject a little better before attempting.
Sorry that I’m unable to give you the reference I did have. ( I hate when that happens !!! )

I have used some semolina flour, felt cutoffs, roof insulators, fibre glass cotton, toilet paper etc
to ensure that the powder stays near the primer in a good tight package.

You can generally use almost anything to fill the space,
but you got to ensure that the powder stays together near and exposed right on to the primer.

Heck most of us have use this method (but not knowingly using it) in shotgun cartridges.

By changing the type of powder, you can bulk up the load in the cartridge
and thus ensure that there is minimal empty space for the powder to float around.
Very fast bulky powders like TrailBoss are great for straight wall cartridges
Bottle neck cartridges would usually require slower powder to work efficiently.

Of course an interior ballistic program can help a lot in determining the type of powder to use to fill the space.

=================

Another way came to mind, but is not recommended for those who do not have the basic knowledge of powder ignition (damianss you are out!).
If to tip the gun up so all the powder in the cartridge fall down near the primer before shooting.
This would only work on very FAST burning powders such as Red Dot or AS-30, but it would be very dangerous to use with slow powders.

Les,
Subsonics are not limited to pistol uses only,
My 300 Whisper is a rifle.
I also shoots 45-70 rifle in subsonics.

I do not believe in 22 cal (centerfire or otherwise) in subsonics unless they are used only for
small varmint like rabbits and foxes in close proximity (less than 50 meters).

Trail Boss is excellent subsonic powder - but NOT if compressed. The whisper case is probably too small. I use 7.62x39 with 180 gr lead and a full case of Trail Boss. I think this is the smallest .30 cal case you could use.

.308 cases should work well with TB, .303s do - about 13 gr from memory.

Good thing about Trail Boss is it is available as ADI or Hodgdon.

Trail Boss is marketed under IMR in the U.S. not Hodgdon !!!

chambered221 wrote:

Trail Boss is marketed under IMR in the U.S. not Hodgdon !!!

I thought at this point its like saying "Tom-atoes Toma-toes"?

Dimitri

If the data was listed in both I’d agree but I’ve only seen it in the IMR publications !!!

I get what your saying, I was referring to the fact that the load date online is with both side by side as they are currently one and the same company.

Dimitri

Usually ADI powders have been marketed as Hodgdon in U.S. but as they now own IMR & Winchester I guess there will be some rationalisation of the number of powders available.

I use ADI where possible as it always seems to be available in New Zealand.

My 7.62x39 wouldn't shoot better than about 6" group @ 100m with AP50 or Vihtavouri N110.

I tried Trail Boss - 1.5" group 5 shots first load. Lee Enfield action.

'Mitri, back in the day well, back when I was shooting target pistol competitively, it was not uncommon for guys to experiment with all sorts of filling for light loads. I'm talking 2.5gns of Bullseye in either a .38 Spl or .357 case shooting a 124gn 9mm Conical cast boolit.

By far, the most successful filling/packing was Dacron. Easily obtainable (any Haberdashery Store would carry it) and it is "dense" enough not to allow pockets of powder to form.

However, as Chambered said...make haste slowly. No sense in hurting your firearm, or yourself mate.

Cheers, Vince

Interesting Ammo.