• Watch Out for Scammers!

    We've now added a color code for all accounts. Orange accounts are new members, Blue are full members, and Green are Supporters. If you get a message about a sale from an orange account, make sure you pay attention before sending any money!

300 Blackout Same as a 300 Whisper??

boomdoggie

Sergeant
Full Member
Minuteman
Mar 5, 2011
205
2
44
Texas
OK I was at a local gun shop not known for their accuracy in information, I asked if they had any 300 Blackout and the sales guy said no but they had 300 whisper and that it was the same round. I have a noveske and really didn't want to blow it up on it maden voyage so I passed and the fact it was $65 bucks a box helped too. My question is were they right or is it total bs
 
Very similar to the .223 and 5.56 situation -- Shooting a blackout in a whisper chamber is a no-no.

Blackout has a higher velocity and is a much hotter load.

Whisper in a blackout chamber is 100% good to go.

The blackout is the standard round, whisper is the "wild".
 
300 MLK is not really much (or any) hotter, check the chamber specs and shooting results mixing ammo here:

http://www.americanrifleman.org/art...ntent=300Whisper-head&utm_campaign=300Whisper

The thing is, this article shows the original 300 whisper reamer as made by hornady with the blessing of JD Jones. There are other non sanctioned "wild" versions of the 300-221 that people also incorrectly call "300 whisper" and you may not know which chamber your rifle has. You can fire a commercially loaded 300 whisper into a 300 BLK chamber, and if in doubt write to the ammo manufacturer to make sure.

Now that BLK 300 is the SAAMI standarized round it makes sense to stick with it.
 
After doing so for no shortage of rounds through various barrels I have to conclude that the above statement may not represent actual fact.

...Blackout is a much hotter round...

That advice was actually given to me by Freedom Munitions when I asked the same question.

The neck size is the same but, just like a .223 vs a 5.56, it's not recommended to go backwards -- Same holds true, here.

At the end of the day, it's your gun, your barrel and you can do as you please but, I doubt you'll find a competent gunsmith in the world that will recommend it.
 
OK I just ordered some 300BLK reloads from Reloads of Dallas so, Until I get my dies in and bullets. I stay away from the whisper just in case
 
OK I just ordered some 300BLK reloads from Reloads of Dallas so, Until I get my dies in and bullets. I stay away from the whisper just in case

If your gun is chambered in a blackout, you're 100% good to go with the whisper.

If your gun is chambered in a whisper, you're not 100% good to go with the blackout because the blackout is a significantly hotter round.

So for you, you can shoot the whisper all day long without an issue but, if your gun were chambered specifically for the whisper (which some are) you don't necessarily want to be shooting the blackout.

This is just what Freedom told me over the phone...

Here's an article on it if you're really curious:

http://www.americanrifleman.org/articles/shades-of-gray/

And a quote from the top of page 2:

But how similar are the two cartridges? Is .300 Blackout ammunition compatible with guns chambered for .300 Whisper and vice-versa? Silver replied: “Hornady .300 Whisper ammo, according to Hornady, has been specifically tested to be within SAAMI specifications for .300 AAC Blackout. If you shoot .300 BLK ammo in chambers that have a shorter or tighter throat, pressures will go up—perhaps above SAAMI maximums—so it is not OK to mix ammo.”

I'm building a 300 blackout right now, barrel due in a few weeks and I had the same exact question...
 
There are no SAAMI pressure specs for 300 whisper, only load data, so you cannot say wich is loaded hotter. If you look in the article you mentioned (the same I posted before) you'll see that velocities are the same for both 300 BLK and 300 whisper factory ammo, fired in guns with chambered for either rounds.

If you look at the chamber drawings, they have the same max. chamber lenght (1.378"), and the free bore in the whisper is .180" vs .174" for the BLK.

The only official (sanctioned by JD Jones, SSK industries) "300 whisper" dies are the ones made by hornady, and they are close enough to the 300 BLK that there will be no problems, as the article shows.

There are other non sanctioned "wild" versions of the 300-221 that people also incorrectly call "300 whisper", that's the source of potential problems.

As the article says in the conclusion:

"Is there really that much difference between the .300 Whisper and the .300 Blackout? Given the fact that major manufacturers such as Hornady are building ammunition headstamped .300 Whisper and recommending it for use in either platform—in addition to producing reloading dies that are marked “300 Whisper/Blackout” and Smith & Wesson stamps the barrel of its M&P-15 Whisper barrels with: “300 Whisper/300 AAC Blackout” it is safe to say that differences are minimal."
 
Smith & Wesson have a 300 Whisper upper that they say you can use 300 BLK in with no issues.

The S&W is chambered with a 300 BLK spec reamer, thus it has the longer leade and can safely chamber and fire either round.
The 300 Whisper moniker was done as a courtesy to Hornady since the intro of the S&W uppers and rifles came out in conjunction with the ammo.
 
Perhaps this is true, but since the freebore in the "true" 300 whisper is actually longer than the 300 BLK, I doubt the leade angle makes that much of a difference.

In any case, all future guns will probably use the 300 BLK since it is SAAMI adopted.
 
...Blackout is a much hotter round...

That advice was actually given to me by Freedom Munitions when I asked the same question.

The neck size is the same but, just like a .223 vs a 5.56, it's not recommended to go backwards -- Same holds true, here.

At the end of the day, it's your gun, your barrel and you can do as you please but, I doubt you'll find a competent gunsmith in the world that will recommend it.

Seriously.............
 
Last edited: