Sigh - AR15

[silencertalk]

http://www.ar15.com/forums/topic.html?b ... 730&page=1

I tried to register on AR15 but they denied my registration so I will need to post here.

So, it's become apparent that longer OALs make for better accuracy and feeding, and removal of a little of the rib on the follower allows the ogive to sit wherever the best feeding and accuracy occurs.

This is not true. We have accuracy data of bullets of all weights (lengths) and the 110 grain have been the most accurate. 115 and 125 were also very good. And anyone who says 1:8 twist is too fast for 110 grain bullets is totally ASSuming.

You may have to shave the follower and support ribs. I wish this had been worked out before they launched it... This is highly reminiscent of the release of the "SAAMI" 6.8

Just like the throat of 6.8 SPC-II is about 0.050 longer than 6.8, 300 AAC BLACKOUT's throat is about 0.050 longer than 300 Whisper(R). So actually, a lot of thought was given to this and it is why 300 AAC BLACKOUT has higher velocity than the 300 Whisper(R) - it is just like 6.8 SPC-II compared to 6.8, or 5.56mm compared to 223.

I am not sure what you think needs to be worked out related to magazines. All factory ammo works with normal magazines - that was a military requirement. If you want to experiment and load ammo long and it is hitting the rib on the magazine, then you can use a modified magazine if you choose, but it is not required.

IMO, calling the BLK " best new release of the year" is an overstatement. The 7.62 X 40 WT has it beat.

7.62x40mm is a wildcat, not subsonic compatible, has no factory brass or ammo, and requires special magazines. Probably only a few hundred people will use it.

Ballistically the 7.62x40 has the 300BLK beat hands down with light for caliber supersonics. An extra 200-300fps with 110-125gr bullets is significant and will matter to hunters and defensive shooters. I get 2600fps from a 16" barrel using 110gr V-Max's with my 7.62x40 (1651ft-lbs). My 300 Fireball is an SBR and wouldn't be fair to compare but most seem to get 2300-2400fps using a 110gr bullet from a 16" barrel with the 300 BLK (1292-1406 ft-lbs). Thas is a 17-28% increase in energy at the muzzle from a 16" barrel using the 7.62x40.

300 AAC BLACKOUT compared to 300 Fireball is like comparing 5.56mm to 223. A 110 grain 300 AAC BLACKOUT bullet is 2450 fps from a 16 inch barrel at 55,000 psi. So it seems like 7.62x40mm is about 150 fps faster, assuming you are loading to 55,000 psi. If you are loading to more than 55,000 psi, then the difference is probably less than 150 fps. With heavier bullets, the difference will be even less.

That wouldn't surprise me as my 300 Fireball (which is a Noveske that is within 300BLK spec BTW) has some issues feeding ammo that is loaded short. There is too much distance from the front of the bullet to the feed ramp and they tend to nose down while feeding. If that is, in fact, the reason the posted loaded lengths have been removed you may well see AAC recommending a different magazine soon.

I took down the list to revise it. I felt that by naming all of those bullets, I was endorsing them as good choices, when in fact some were not for ARs (they are ok for bolt actions). People keep on asking if 30 Carbine bullets are good for 300 AAC BLACKOUT. They are generally not for ARs. On the next printing of the owner's manual it will have a revised list of recommended OALs. Sierra is going to publish loading data of a bunch of their bullets which I have selected as good choices. There are also a few new bullets coming out which are optimal.

[bp_968]

Sometimes I wonder about some people who try to reload. OAL is hugely important even in a bolt gun (consistency, etc). You'd think it would be obvious which bullets wouldn't work all that well out of an autoloader.

And of course they denied your registration. That place is typically a useless mess. people who have 1 of an item telling people its the best (like they have experience outside it) or worse, people who've seen it on the web bet never touched it who are suddenly product guru's.

I'm very interested in how this caliber plays out. Do you think it's a product improvement over the 6.8 in supersonic applications? I could be way off, but if the .Mil wants to keep weapons compatibility in their inventory this looks like it could be a holy grail. The barrel is the only thing that's different over a 5.56 correct? With the .Mil's interest in ever shortening barrel lengths this could be a really viable choice. How are its longer range (500yds?) ballistics with a good LR .30cal bullet (say like the Lapua 155gr).

Ben

http://www.ar15.com/forums/topic.html?b ... 730&page=1

I tried to register on AR15 but they denied my registration so I will need to post here.

So, it's become apparent that longer OALs make for better accuracy and feeding, and removal of a little of the rib on the follower allows the ogive to sit wherever the best feeding and accuracy occurs.

This is not true. We have accuracy data of bullets of all weights (lengths) and the 110 grain have been the most accurate. 115 and 125 were also very good. And anyone who says 1:8 twist is too fast for 110 grain bullets is totally ASSuming.

You may have to shave the follower and support ribs. I wish this had been worked out before they launched it... This is highly reminiscent of the release of the "SAAMI" 6.8

Just like the throat of 6.8 SPC-II is about 0.050 longer than 6.8, 300 AAC BLACKOUT's throat is about 0.050 longer than 300 Whisper(R). So actually, a lot of thought was given to this and it is why 300 AAC BLACKOUT has higher velocity than the 300 Whisper(R) - it is just like 6.8 SPC-II compared to 6.8, or 5.56mm compared to 223.

I am not sure what you think needs to be worked out related to magazines. All factory ammo works with normal magazines - that was a military requirement. If you want to experiment and load ammo long and it is hitting the rib on the magazine, then you can use a modified magazine if you choose, but it is not required.

IMO, calling the BLK " best new release of the year" is an overstatement. The 7.62 X 40 WT has it beat.

7.62x40mm is a wildcat, not subsonic compatible, has no factory brass or ammo, and requires special magazines. Probably only a few hundred people will use it.

Ballistically the 7.62x40 has the 300BLK beat hands down with light for caliber supersonics. An extra 200-300fps with 110-125gr bullets is significant and will matter to hunters and defensive shooters. I get 2600fps from a 16" barrel using 110gr V-Max's with my 7.62x40 (1651ft-lbs). My 300 Fireball is an SBR and wouldn't be fair to compare but most seem to get 2300-2400fps using a 110gr bullet from a 16" barrel with the 300 BLK (1292-1406 ft-lbs). Thas is a 17-28% increase in energy at the muzzle from a 16" barrel using the 7.62x40.

300 AAC BLACKOUT compared to 300 Fireball is like comparing 5.56mm to 223. A 110 grain 300 AAC BLACKOUT bullet is 2450 fps from a 16 inch barrel at 55,000 psi. So it seems like 7.62x40mm is about 150 fps faster, assuming you are loading to 55,000 psi. If you are loading to more than 55,000 psi, then the difference is probably less than 150 fps. With heavier bullets, the difference will be even less.

That wouldn't surprise me as my 300 Fireball (which is a Noveske that is within 300BLK spec BTW) has some issues feeding ammo that is loaded short. There is too much distance from the front of the bullet to the feed ramp and they tend to nose down while feeding. If that is, in fact, the reason the posted loaded lengths have been removed you may well see AAC recommending a different magazine soon.

I took down the list to revise it. I felt that by naming all of those bullets, I was endorsing them as good choices, when in fact some were not for ARs (they are ok for bolt actions). People keep on asking if 30 Carbine bullets are good for 300 AAC BLACKOUT. They are generally not for ARs. On the next printing of the owner's manual it will have a revised list of recommended OALs. Sierra is going to publish loading data of a bunch of their bullets which I have selected as good choices. There are also a few new bullets coming out which are optimal.

[silencertalk]

It is only as powerful as 6.8 in short barrels. With normal barrels, 6.8 is more powerful.

I plan to have 300 AAC BLACKOUT become more popular by having lower priced ammo, and the normal magazines and bolts helps.

The biggest miscalculation is when people assume everyone only wants the most powerful round no matter the cost. 40 S&W is much more popular than 10mm.

[Bowen1911]

i had never even heard of that 7.62x40

looks retarded.

[bp_968]

It is only as powerful as 6.8 in short barrels. With normal barrels, 6.8 is more powerful.

I plan to have 300 AAC BLACKOUT become more popular by having lower priced ammo, and the normal magazines and bolts helps.

The biggest miscalculation is when people assume everyone only wants the most powerful round no matter the cost. 40 S&W is much more popular than 10mm.

I agree, I sold my 40cal and got a 9mm since I shoot so much suppressed. The difference between them for defense is slim and eclipsed by the importance of shot placement.

How well do you think it would work with a SWR Omega 30 thread on can? I wouldn't mind building a 300blk upper but don't have the extra cash for another can just yet.

[silencertalk]

A 308 cal can is good.

I don't think a 7.62x40mm is bad, but it is like 41 AE - an idea that has no chance for various reasons. It is a flawed assumption that people want that last ounce of power at any cost.

[Fastflt1]

Off topic a bit but ironic all the same.

First post for the OP on AR15.com:

New to AR15.com and really dont know how forums work but i could not find a thread on the AAC 300 blackout so I am starting one.

What are the pros and cons to this round vs the 5.56? I am building my first AR and it is a SBR that will eventually have an AAC can on it. It will be a noveske barrel at about 10-11.5 inches long. I can not decide on a 5.56 or the new AAC 300 blk. So can you guys help? Here is the deal PLEASE STAY ON TOPIC. I hate when these things get off topic as it helps no one.

I have seen AAC's website on the round and it says up to 400 yard engagement but at something like 80 clicks at 1/4 moa, that is not feasible, and honestly i dont see reaching out past 150 yds. so lets compare the rounds out to 150 yds. What are the pros and cons?

Thanks in advance for the help.

Hmmm...somebodies fishing

[rob_s]

He corrected himself on the follower modification. I'm still interested to see how the magazine body issue works out.

re: the x40, I think he's missing the boat, but we are all victims of our own frame of reference.

[Bowen1911]

the 7.62x40 doesn't look like it can take heavy bullets at all. no wide bullet selection sucks balls

[silencertalk]

the 7.62x40 doesn't look like it can take heavy bullets at all. no wide bullet selection sucks balls

It is best for bullets up to about 130 grains.

[Bowen1911]

the 7.62x40 doesn't look like it can take heavy bullets at all. no wide bullet selection sucks balls

It is best for bullets up to about 130 grains.

So the benefit to that is???

Versatility is a huge factor on if a new caliber is appealing to me. and being able to shoot 110 to 130 grains out of an auto loader (not as a plinker, or else why would i have gotten it in the first place? 5.56 is cheaper) is not versatile from a 30 cal platform.

That guy is a turd. sometimes i want to reach through the screen to slap people

[silencertalk]

Right. It is like 338 Lapua Magnum - they made the case too long and you cannot shoot 300 grain bullets in it properly. It was really designed to just shoot 250 grain Lapua bullets. Then the 338 Norma mag came out to fix that problem. Some people are learning lately to not make your case too long when you design a new cartridge.

[curious sam]

The biggest miscalculation is when people assume everyone only wants the most powerful round no matter the cost. 40 S&W is much more popular than 10mm.

Correct. I think 300 give the best... horsepower to weight ratio I've seen, and that I what I personally consider.

The dual capability, 7 lbs with can, 30 round mags, etc etc etc - I've been playing with ARs for quite some time, own a bunch and have owned countless guns.

This round appears to be a unique snowflake with more potential due to its capabilities and the way it is being supported and marketed than anything I've seen in a LONG time.

Perhaps, dare I say - since the 40 S&W.