No it is from a 16" barrel. The 7.62x39 with surplus ammo is faster than a 300blk with premium ammo.
How do you know they did not test in the normal SAAMI barrel length?
It’s a great way for you to try to make the 300 whisper/blk better than it is. I’ll give you this the 300whisper/blk is a great subsonic cartridge within the limitations of the AR15 platform.
The same Wolf ammo produces apx 2450 out of my 16" barrels, that’s not 1 barrel tested that is 5 from each lot of 100 barrels produced over the past 3 years. Winchester also produces that velocity, the Remington ammo is almost 100fps slower.
If you take a SAAMI chamber and ream it to SPC-II specs, it will drop pressure by 1000 psi. You can then add powder in order bring the load back to a full 55,000 psi, and that will give you the 20-30 fps of additional velocity.
You are well aware of my emails to the Western Powders ballistics lab:
Johan,
Have you ever done a test where you take a 6.8 SPC SAAMI test barrel, measure velocity and pressure, then ream the same barrel to 6.8 SPC-II - and add more powder to match the pressure of the previous test, and then see how much extra velocity there is?
Robert.
Robert,
Yes we did exactly that and the difference was negligible as to be ignored ca 20-30Fps and <1000Psi.
I know there is a lot of claims out there regarding this.
Some apply the effects of other calibers (such as the 223Rem) with completely different expansion ratios to the 6.8SPC.
The 6.98Spc is not sensitive to the slight changes in dimensions between the std and SPEC II.
Regards
Johan Loubser
Ballistician
Ramshot.Accurate.Powders
From Art at SSA:
I can not disagree with Bob’s statement of only 1000 -1500 PSI reduction and <30 FPS increase with a given load and projectile with respect to the SAAMI VS the Spec II chamber
You have read my posts before on this and they are not sinking in. I do use the numbers from the ammo specs:
Lapua 123 grain 7.62x39mm - 712 Joules at 300 meters (16.5 inch barrel). This is 525 ft-lbs.
http://www.lapua.com/en/products/special-purpose/centerfire-rifle/19
Remington Match 125 grain 300 AAC Blackout - 618 ft-lbs at 300 meters (16.0 inch barrel (0.320 BC, 2215 fps muzzle velocity)).
Advantage - 300 AAC Blackout by 16%, even with slightly shorter barrel.
Yes they are, but 300 BLK overtakes 7.62x39mm at around 100 yards and has about 17% more energy at 300.
I am not going to go by your chronograph data because it was measured in a rifle, not a test barrel, and your chronograph is of unknown calibration. For the same reason, I don’t say that the Remington 125 grain ammo which is rated at 2215 fps (instrumental, meaning, not at the muzzle) gets closer to 2300 fps in my guns on my personal chronograph. I don’t use my own data even though it is favorable. Factory / lab data only, in verified test barrels, with professional instrumentation for comparison purposes. The same rules apply to me.
Well I don’t believe you or your info either so we can leave it at that.
As I told you before if you stay out of the 6.8 threads I’ll stay out of your 300 threads or we can both jump in, tell our sides and let the people purchasing make their own decision.
I’d rather rsilvers stay out of both.
BTW I use a Oehler and CED back to back. They work.
As for test barrels no one buys test barrels to use on a rifle, they use barrels made in the real world and that is what we sell.
2 rifles side by side with production ammo, the 7.62x39 is 200fps faster than a 300whisper/blk.
Test barrels are generally used in a universal receiver.
Yes, I know 7.62x39mm is generally faster at the muzzle. I have said that, though I don’t acknowledge it is 200 fps faster as a fact if both are in 16 inch barrels.
Winchester’s website lists Q3174 Caliber: 7.62x39mm Bullet Weight: 123 Grains Bullet Type: Full Metal Jacket. Test Barrel Length: 20" Velocity in Feet Per Second: - Muzzle: 2355.
300 BLK 125 grain is 2315. When you downgrade the Winchester to a 16 inch barrel, it is not faster.
Hornady V-MAX, 2350 fps from a 20" barrel. In a 16 inch barrel this would be about 2240 fps.
Lapua http://www.lapua.com/en/products/special-purpose/centerfire-rifle/19
715 meters/sec from a 420mm barrel (16.54 inches) - that is 2346 fps. Downgrade that a little from a 16.5 to a 16.0 inch barrel, and it is about 2330 fps.
300 BLK overtakes all of these by about 100-120 yards and at long ranges has much more energy.
Now in order for you to be correct about your 200 fps claim, you are going to have to show that the manufacture’s own data is not valid, and also that Winchester, Hornady, and Lapua are not quality sources of ammunition.
The difference between you and I is you search the internet night and day for information I actually build rifles and test them, real metal, real ammo, real chronos. I only make 16" 7.62x39 barrels so all of my readings came from 16" Melonite treated barrels. The 300 whisper/blks were 8 twist the 7.62x39s were 10 twist.
Winchester and Wolf ammo is apx 100fps faster than the Remington ammo I tested, it was all production ammo. Test barrels and test ammo doesn’t tell me jack because customers aren’t buying test barrels and test ammo. I buy and test exactly what they would.
The 300whisper/blk is a nice range toy for most and may be a better option for subsonic work and replacing the MP5. If you are trying to sell it as a better terminal performing hunting round than the 7.62x39 or 6.5G/264 or 6.8 forget it. I know you wont after seeing you spend a whole year on 6.8 forums trying to convince everyone there the 300 whisper/blk is better.
As far as the barrel the powder co tested how many grooves did it have?, what was the bore area of the barrel? Did the SPCII chamber they had in it have a 80 degree cone angle or a 45 degree cone angle? Was it a 10 twist or an 11 twist?
So their testing as performed and if reported correctly only made a slight change if only the chambers were changed and YOU say twist makes no difference at all?
I wonder why Art of SSA changed the chambers to correct a over charged ammo problem back in 06 and he said it corrected all of the problems that nothing else needs to be done. we’ll get back to that one.
I do too - I just test fired 24 rifles. Your data, and my data from actual rifles, is not as reliable as the lab data from Winchester, Lapua, and Hornady for comparison purposes - because universal receiver test barrels are verified against drawings to be within a certain tight tolerance range. Normal rifle barrels are subject to a much wider variation.
Let’s make every effort to strip the “you versus me” banter out of this discussion, gents. Either we find a way to present and explain the facts with mutual respect and consideration (whether we happen to agree or not) or we will see this thread closed and the appropriate bludgeonings administered.
AC
^^^ This!!
To the op, if you want an effective hunting round in an AR platform the 6.8 is outstanding!! Don’t believe the hype from guerilla marketers, do the research yourself and you will see the 6.8 will perform well for you in a hunting role.
So how many people on this forum go home and grab their universal receivers and test barrels to shoot?
Real world products and real world data is what matters to the consumer because the other stuff can only be repeated in a lab.
With this statement "You guys just need to stop with this nonsense of using one company’s over-pressure ammo as proof your cartridge has magical powers. That ammo is loaded to an OAL which only works in one brand of magazine and is not in spec. It is also over normal pressure.
I can load Lapua Scenar 155s in 300 BLK to above normal pressure and to the same OAL as the ammo you just cited and get 2150 fps and that will go transonic at 900 yards.
Let’s get real compare favorite bullets in each caliber at normal pressure:
The .308 110 T-TSX BC is 0.295. So at 200 yards, that is 1871 fps, and 855 ft-lbs.
An 6.8 85 grain bullet which started at 2800 fps and ended up at 2076 fps is 823 ft-lbs.
So based on energy with the best bullet in each caliber, the 300 BLK actually has a 4% advantage at 200 yards.
However, when I said 80 yards more range for the 6.8, that was going by max point blank range - and I used a 6.8 bullet with a better BC than the 85 TSX to be completely fair.
I stand by my 80 yards. "
You are comparing the best bullet made for the 300 whisper/blk to the lowest BC bullet made for the 6.8. Do you think that is manipulating the data a “little” to make one look better than the other? If you want to compare the 300 to the 6.8 take the best bullet made that consumers can purchase in each caliber and compare the energy and trajectory and expansion thresholds of each.
SSAs 140gr Berger load is the only factoy load that has an OAL of 2.295…there are factory magazines that allow using those factory loads…that makes them available to and usable by the consumer.
Is just because You say something is out of spec mean it is not available for purchase and used by the consumer to get those results? I think the ammo products made by Wilson Combat and SSA are a hell of a lot more usable than the test barrels and universal receivers therefore a more valid comparison when it comes to information that would be important to a consumer when deciding what they want to purchase based on performance.
The only companies producing SAAMI spec barrels now are Remington, Ruger and LMT…maybe that has changed. Every other company that I know of produces a high performance chamber.
Constructor , I ordered one of your barrels and bolts (will they be headspaced?) and I will give 6.8 a try. I will continue to use my 10" 300 since it seems to work well out of the short barrel. I am looking forward to experimenting with the 6.8 to see what it can do with a 16" barrel (300 doesn’t seem to make much sense out of longer barrels)
Yes, they are headspaced.
I can get 2150 fps out of my 12.5" .30HRT with the Lapua Scenar 155s or 2250 out of my 16" barrel --Easily beats the blk. That being said it is still not as good as my 6.8
That’s a lil’ harsh.
I appreciate the knowledge R. Silvers shares. Constructor also. Funny thing is their argument sounds like what kills better “stones” or “rocks”. dead is dead and they both fit the EXACT same role when it comes to game. I find it hilarious when someone says to step up from 300 blk to 6.8 for the really big hogs.
another 300 vs 6.8 argument… ugh
when i see the 300 have the following for hunting like the 6.8 does, then and only then will i give a crap about the 300wtf. :rolleyes: