New Caliber - 300 AAC Blackout

[R.W.Dale]

I asked this question in an older (three page) thread and it promptly died, so I'll ask it again in this more active one.

Does this thing headspace off the leade or the extractor?

What makes you think it would headspace anywhere but the shoulder?

What cartridges headspace on the extractor or leade?



Where does the cartridge on the left headspace?

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[alemonkey]

I think he was making a funny, since it doesn't have much of a shoulder.

 

[R.W.Dale]

I think he was making a funny, since it doesn't have much of a shoulder.

In which case trying twice to have the bait work smells something trollish

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[Elkins45]

Not trolling, just making a point. The 35 Whelen got a bad rap for headspace issues in bolt guns and it has a veritable ledge for a shoulder compared to this round... and it's designed for autos.

There's been a lot of research in recent years that shows a number of autoloading handguns, particularly ones chambered for 45ACP actually headspace on the extractor because the case mouth falls short of the end of the chamber when the gun goes into battery. I wouldn't be surprised if that's not happening with this round. Or the opposite- that when in battery the bullet is engaging the lands-though that might not be possible if it is functioning from the magazine. I have a particularly troublesome 35 Whelen that I have to seat the bullet just barely inside the case mouth when fire forming cases. It actually headspaces on the leade until I can get the shoulder fully blown out. You don't think that could be happening here?

 

[R.W.Dale]

No

35 Remington has less shoulder than 35 whelen and has been functioning in autoloaders since 1906

Don't interject your problems with an ad hock kitchen table gunsmith rebarrel job using reformed brass with a properly engineered and produced cartridge. I've built and owned a couple of 35 whelens. I can say with certainty that your problems are of your own creation through either pushing the shoulder back too far or from having too much headspace

The 300 BLK and its forerunners have been headspacing just fine for close to 40 years now

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[Elkins45]

I can say with certainty that your problems are of your own creation through either pushing the shoulder back too far or from having too much headspace

Despite your certainty you would be wrong according to a set of Forster headspace gauges and a box of factory new brass. There are complexities in mechanical systems that don't always fit into the certainty of your pronouncement.

But this is thread drift and I'll end it on the high road: I'm happy this cartridge appears to function well and that people are finding it useful.

 

[usglfvet]

Well..........that was a thread killer...........

 

[rsilvers]

Aimpoint Micro with no magnification at 100 yards. 5 shots. 9 inch upper.

 

[rsilvers]

http://www.midwayusa.com/product/54...62x35mm-115-grain-full-metal-jacket-box-of-20

 

[A Pause for the Coz]

Pretty sure I will be getting one.
Going pick up some of these.
http://www.allweatherarms.com/1000-...out-Brass-1000-Pcs-Processed-300-Blackout.htm

Then start slinging some Gas Checked Cast Bullets.

 

[Strykervet]

Will be doing my form for the SDN6 this weekend. Already have the Blackout mount. Talked to Satern today and will be calling them back about the barrel construction tomorrow. Can't wait to get this thing running, probably sometime next year around this time considering wait times on those custom barrels. I have a pretty good idea for the build on this one too, can't wait to start it. Never been more excited about an AR build, even my Grendel which is my favorite.

Might as well get the dies and some more LC brass and start forming it in the meantime. It'll need food when I get it anyway.

 

[Hammerhead6814]

Anyone handloading for this manage to get 125 gr round close to 2,400 fps? Friend of mine is an AK fan who I can't get to shut-up about this.

 

[rsilvers]

300 BLK cannot do 2400 fps with a 125 grain from a 16 inch barrel. It can do it with 110 grain.

Can't get him to shut up about 300 BLK being cool? Or can't get him to shut up about not being able to do 2400 fps?

 

[R.W.Dale]

300 BLK cannot do 2400 fps with a 125 grain from a 16 inch barrel. It can do it with 110 grain.

Can't get him to shut up about 300 BLK being cool? Or can't get him to shut up about not being able to do 2400 fps?

In a 16" bbl 7.62x39 is kind of stretched to do 2400 too. Most rifles and loads will fall short of this mark over a chrony.

Here's a link to some testing I did back when I was a total x39 fanboi

http://www.gunrightsmedia.com/showthread.php?t=402888

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[rsilvers]

20 shot group from a 300 BLK AR at 100 yards with Hornady 155s and iron sights. Not shot by me. Shot prone, not from a rest.

 

[rsilvers]

I already spent a lot of time on the 7.62mm comparison. I found what is likely the hottest ammo - Lapua ($40+ a box at Midway) - and they have good data from their website. It starts out as a little more energy than 300 BLK, but by 120 yards, the BLK overtakes it - and at 300 meters, the BLK has 16.7% more energy. This is due to the higher BC of the Sierra 125 grain 300 BLK bullet.

 

[rsilvers]

300 AAC Blackout is the #1 most popular rifle cartridge at MidwayUSA - there is no 223/5.56mm load - or any cartridge for that matter, that is higher ranked.

 

[R.W.Dale]

You can't go by that

I've seen the midway software put 8x56r and .310 CADET on top.

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[rsilvers]

Can't go by the Top-40 hits metrics either - it is a group called Pit Bull this week.

 

[rsilvers]

300+ lb pig, 100 yards, Barnes T-TSX 300 AAC Blackout Black Tip ammo, AAC 16" upper - dropped right there.

 

[rsilvers]

 

[jmstevens2]

This thread is still being pushed along?

 

[Hammerhead6814]

rsilvers is trying to keep the .300 in the headlines and on the first page. Can't blame him, he's got a lot invested in it.

 

[usglfvet]

@jmstevens You can always ignore it or was your latest post to promt a negative response from others? I have enjoyed every post on this thread and look forward to the next. I actually got in touch with Rock River Arms to see if they had any plans on a 300 Blackout. So I could stay with the same manufacturer as the AR I already have. They don't so I am still shopping as I slither cash away for my next unauthorized male purchase. Would prefer an upper rather than just a barrel change money permitting.

 

[Tirod]

There's benefits to keeping up. The point is trying to live with an overall length of 2.300", and a maximum bolt face of the x39/6.5G case. In between, you can mess with case length, case diameter, bullet length, bullet diameter, and attempt to balance out with BC, powder, and primer.

What results is a pretty small niche in the overall balllistics table, you either shorten the range with big fat non aerodynamic bullets, or lengthen it with high BC bullets, but they all fit from about 55 to 140 gr, and 2300 to 3000fps. You trade off speed, footpounds, and range inside that envelope, but you can't have all three.

That means the job at hand requires the cartridge that fits best, and the experienced shooter chooses that. How wide the scope of application is can bear on that a lot. What's nice about the current interest in the .300's is that there is still very little of the One Cartridge To Rule Them All fanboy thinking.

We could just as easily be reloading telescoped polymer cased high BC bullets using the some kind of stacked powder pills in 20 years. On a plastic press.