S&W M&P AR in .300 Whisper (factory rifle)

[Titleiiredneck]

Originally Posted by rsilvers

Yeah, that is incorrect. First, this rifle is actually chambered in 300 BLK, .

Look at the s&w website, says it's chambered for both. Pp
http://www.smith-wesson.com/webapp/w...51_757784_-1_Y

[rsilvers]

Yes, well, sales and marketing people don't know. A Whisper(R) chamber would be smaller than a Blackout chamber, so in order to be both, it has to be a Blackout chamber.

[Alleycat]

Originally Posted by rsilvers

Yes, well, sales and marketing people don't know. A Whisper(R) chamber would be smaller than a Blackout chamber, so in order to be both, it has to be a Blackout chamber.

I ordered some factory Blackout ammo to find out. I have a SSK Whisper and a Blackout. We shall see.
http://http://www.midwayusa.com/prod...-otm-box-of-20

[Spook]

Originally Posted by rsilvers

A Whisper(R) chamber would be smaller than a Blackout chamber, so in order to be both, it has to be a Blackout chamber.

How do you know that to be the case?

[rsilvers]

How do I know a Whisper(R) chamber is smaller than a 300 BLK chamber? Because a big ammo maker (not Remington) told me they test their ammo in the smallest of the Whisper chambers because that is the one which gives the highest pressure (this does result in lower velocity ammo though).

Or how do I know that in order to use both in the rifle, it would have to be a BLK chamber? Because that is the deal with 223/5.56mm and 6.8 SAAMI/6.8 SPC-II - smaller chambers raise pressure. So you have to use the largest reamer you rate it for.

[Ned christiansen]

Whatever chamber dimensions they are using, I think we may find that they are calling it Whisper because it is being done n cooperation with JD Jones..... just guessing.

[Alleycat]

http://http://www.hornady.com/new-products/300-whisper

Compatible with guns chambered for the 300 AAC Blackout, the 300 Whisper from Hornady is a reliable performer with or without a suppressor and brings a new level of flexibility to the AR-15 platform.

I guess Hornadys people F'ed up too.

[rsilvers]

I would expect the Remington ammo to go over max SAAMI pressure if you shot it in a tight Whisper(R) chamber.

You can make ammo that will shoot in both (just like making 6.8 ammo) - it just won't reach as much velocity as if you loaded it just for 300 BLK, as Remington does.

[Alleycat]

It looks like Remington would make brass to the Blackout specifications rather than the Whisper specifications. I have 500 new primed Hornady brass and some sample 300 Blackout brass and they spec out exactly the same. They even weigh the same. (83.3 grains give or take a couple of tenths) If Remington made their brass to Blackout spec, it wouldn’t even chamber in a Whisper because of the huge difference in chamber dimensions. I have measured fired brass out of both guns. The neck in the Blackout expands 0.001” more than the Whisper and the shoulder expands 0.003” more than the Whisper. My hand loads will not chamber in the blackout because of the Whisper’s longer throat. Fired, but unsized cases from the Blackout will not chamber in Whisper with finger presser. Both types of brass are identical to the brass I have made for years. The only exception is that I trim a little shorter.
The smallest 300 WTF I know of is the 300-221 Fireball. I have no experience with this chamber. I would think ammo manufactures would load for the smallest chamber or change it enough so that it will not load in the similar chamber for legal reasons. Getting Robert to admit that would be as hard as getting Kwik2sue to admit his agenda. Robert I do understand your reluctance and I have taken up for you much to the chagrin of people I consider good friends, but sometimes it’s better to say nothing at all. Evil gunsmiths that know better would approve. I know you’re a bright guy, you invented this.

http://www.photomosaic.com/

[martineta]

I have contender and encore barrels in 300 Blackout, 300 Whisper and one lonely 300-221 Fireball. I only have a set of 300 whisper dies. All my 300 Whisper reloads work fine in all three chamberings. They slide right in the chambers easily and slide right out after fireing. All shoot excellent. What gives? I'm happy.