6mm CM

[rifleman762]

If you doubt my impact energy claim, here's the numbers at 300 yards:

243 Winchester 90gr Accubond (or Ballistic Tip): 1100 ft lbs

6mm Creedmoor 103gr ELD-X: 1450 ft lbs

That's a 32% increase in bullet energy at a common hunting distance. Just from a fast twist barrel combined with a high-BC bullet. That's about the same increase in energy that you get from going from a 30-06 to a 300 Win Mag.

 

[Buckmastr]

Shoot a 103 from a 243win faster then a 6 Creedmoor and it betters the energy. If energy is important to you.

 

[SuperCub]

If you doubt my impact energy claim, here's the numbers at 300 yards:

243 Winchester 90gr Accubond (or Ballistic Tip): 1100 ft lbs

6mm Creedmoor 103gr ELD-X: 1450 ft lbs

That's a 32% increase in bullet energy at a common hunting distance. Just from a fast twist barrel combined with a high-BC bullet. That's about the same increase in energy that you get from going from a 30-06 to a 300 Win Mag.

Funny stuff ...... You compare different very 6mm bullets in each and get different results. That's a shocker! <eye roll>

Then you draw the line to the energy increase of the 300magnum over the 30-06 but that's not about bullets it's about a big increase in case capacity.

Apples to oranges again.

 

[Weatherby Fan]

Ackley was doing 30 and 40 degree shoulders and blowing case bodies straight long before the Creedmore was ever thought up. It allowed more powder for a little extra velocity and extended case life, that's pretty much all it does.
This whole notion that you can go faster with less powder capacity due to case design is a myth, velocity is a result of pressure generated by ### amount of powder.
Otherwise we would see Weatherby cartridges winning long range target matches as they have the most efficient sharpest shoulder angle, and they would also be considerably faster then their similar capacity cartridges like the 7mm Weatherby vs the 7mm Rem. We don't see either of those.

Ackley was just a little ahead of his time, the 280AI has really shown the 280 Rem the door and for good reason.

The reason you don’t see Weatherby cartridges winning matches is they are mostly inefficient overbore cartridges with belts, it’s that simple, Roy wanted a different cartridge design to corner the ammo market for his rifles, you will see in the coming years Weatherby will introduce several non belted cartridges and I bet not one of them will have a shoulder taper less than 30 deg or a short neck.

243 win 1955 technology ....I bet they may make a better version of the 243 cartridge some day

 

[rifleman762]

Shoot a 103 from a 243win faster then a 6 Creedmoor and it betters the energy. If energy is important to you.

Sure, and when it tumbles through the air because your twist rate is too slow...happy hunting!

I'd personally go with a custom barrel in 6mm SLR 1:7.5 twist but that's not what the OP was considering.

 

[rifleman762]

Funny stuff ...... You compare different very 6mm bullets in each and get different results. That's a shocker! <eye roll>

Then you draw the line to the energy increase of the 300magnum over the 30-06 but that's not about bullets it's about a big increase in case capacity.

Apples to oranges again.

Uh, yeah, I compared different bullets. Because if I tried to shoot the 103 ELD-X from a factory 243 (OP didn't sound like he's considering custom barrels) then it wouldn't even make it to the target... That would be a poor choice of bullet for a factory 243, would it not?

Energy increase at impact is energy increase at impact. Doesn't matter how you get there! But getting there with better bullets instead of higher velocity is cheaper and easier.

 

[Buckmastr]

Sure, and when it tumbles through the air because your twist rate is too slow...happy hunting!

I'd personally go with a custom barrel in 6mm SLR 1:7.5 twist but that's not what the OP was considering.

A factory model 700 has enough twist to stabilize 107’s. So nothing is tumbling

 

[prevost12]

Shoot a 103 from a 243win faster then a 6 Creedmoor and it betters the energy. If energy is important to you.

Just because you own a singular rifle that you’re able to push far over max doesn’t conclude that a .243 is in the same class. It’s completely anecdotal. Shorter throat, slower twist, worst cartridge. It’s just older, no big deal. Companies learned over the years that some case design features yield better average results. If you bought 100 rifle in each caliber and attempted to run 103-115gr bullets, it’s not even close.

 

[Buckmastr]

You don’t need to run a 9.125T over max to get it to stabilize. The 6 Creedmoor is on its way out.

Weatherby dropped it quickly and replaced it with a 243 Win. They are probably the most innovative manufacturers in the past couple of years.

Browning chambered it too, but discontinued it as well.

 

[rifleman762]

A factory model 700 has enough twist to stabilize 107’s. So nothing is tumbling

Ok, feel free to use marginal twist rates. Not my business. A lot of guys shooting those 105/107 class bullets do it in the summer time, not in -15° deer hunting season. YMMV, as always. Maybe it will work. The threads I've seen of guys shooting the 103 ELD-X in a 9-ish twist barrel were asking for help because they can't get it to group at 100 yards. I haven't tried that combo myself and the numbers are on the edge so I wouldn't advise someone that it's guaranteed to work.

 

[SuperCub]

Uh, yeah, I compared different bullets. Because if I tried to shoot the 103 ELD-X from a factory 243 (OP didn't sound like he's considering custom barrels) then it wouldn't even make it to the target... That would be a poor choice of bullet for a factory 243, would it not?

I get that. So based on that, this is a comparison of rifles not cartridges, right?

 

[rifleman762]

I get that. So based on that, this is a comparison of rifles not cartridges, right?

I don't understand what you're getting at. A factory 6mm Creedmoor rifle IS a different rifle from a 243 Winchester rifle. They come with different twist rates.

I don't understand why you would use the same bullet in two different cartridges that have twist rates optimized for DIFFERENT bullets. It defeats the purpose, does it not?

 

[prevost12]

I don't understand what you're getting at. A factory 6mm Creedmoor rifle IS a different rifle from a 243 Winchester rifle. They come with different twist rates.

I don't understand why you would use the same bullet in two different cartridges that have twist rates optimized for DIFFERENT bullets. It defeats the purpose, does it not?

I’ve been over this a couple times already, it’s fruitless....

 

[rifleman762]

Would you insist on using 50gr bullets only when comparing the ballistics of a 1:12 22-250 to a 1:7 223 Remington? I think that would be silly. But that's just me.

 

[Hitzy]

If you doubt my impact energy claim, here's the numbers at 300 yards:

243 Winchester 90gr Accubond (or Ballistic Tip): 1100 ft lbs

6mm Creedmoor 103gr ELD-X: 1450 ft lbs

That's a 32% increase in bullet energy at a common hunting distance. Just from a fast twist barrel combined with a high-BC bullet. That's about the same increase in energy that you get from going from a 30-06 to a 300 Win Mag.

Why not a 100gr in the 243 for comparison? 1/10 twist shoot those just fine as well.

 

[Hitzy]

Another benefit to these newer cartridges is the throat design. Many older cartridges' SAAMI chamber design specifies a tapered throat that starts out much larger diameter than the bullet. This is a major reason why we usually had to load close to the lands for good accuracy.

These newer designs specify a parallel throat that is only 1/2 a thou over bullet diameter. This keeps the bullet more concentric to the bore even when you aren't loading to the lands.

BTW, to those folks who like to compare identical bullets in the 243 and 6mm Creedmoor to "prove" that the 243 is just as good, why don't you shoot a 103 ELD-X from a factory 243 and a factory 6mm CM and see which works the best? Apples to apples, right? ;-)

And to those who say ballistic coefficient doesn't matter for hunting... Your bullet starts slowing down and losing energy the instant it leaves the barrel. Muzzle energy is irrelevant, impact energy matters. Why use a bullet that loses more energy than necessary? Some people step up to magnum cartridges for more energy. Why not step up to a high-BC bullet for more energy? Same result, different way of getting there.

Mostly because the high BC bullets are basically thin jacket target bullets and perform ####ty on game. The only bonded LR bullet I'm aware of is the ABLR, and it's even a fairly ####ty performer on game.

 

[SuperCub]

I don't understand what you're getting at. A factory 6mm Creedmoor rifle IS a different rifle from a 243 Winchester rifle. They come with different twist rates.

I don't understand why you would use the same bullet in two different cartridges that have twist rates optimized for DIFFERENT bullets. It defeats the purpose, does it not?

Looks like we agree with each other then. Different rifles and how they are set up require different bullets to optimize performance from those rifles.

 

[track]

I don't understand what you're getting at. A factory 6mm Creedmoor rifle IS a different rifle from a 243 Winchester rifle. They come with different twist rates.

I don't understand why you would use the same bullet in two different cartridges that have twist rates optimized for DIFFERENT bullets. It defeats the purpose, does it not?

So, we have a different rifle, different cartridge, different bullet weight, however the same caliber. One shoots faster with less less energy and BC., on the other-hand; the other shoots slower, with a higher energy and BC. Sounds elementary to me, but where is the wiz-bang euphoria? Where is that giant leap of delight with this new cartridge?

 

[Hitzy]

Ackley was just a little ahead of his time, the 280AI has really shown the 280 Rem the door and for good reason.

The reason you don’t see Weatherby cartridges winning matches is they are mostly inefficient overbore cartridges with belts, it’s that simple, Roy wanted a different cartridge design to corner the ammo market for his rifles, you will see in the coming years Weatherby will introduce several non belted cartridges and I bet not one of them will have a shoulder taper less than 30 deg or a short neck.

243 win 1955 technology ....I bet they may make a better version of the 243 cartridge some day

The belts don't do anything to affect accuracy in any way good or bad, they just make for a strong cartridge head. And most Weatherby cartridges have nice long necks.
7mm Rem and 300Win are still used for long range target shooting today and work fine.
Weatherby may come out with more unsellable cartridges like the the 6.5 RPM in different calibers, but they will flop like the 6.5 RPM already has, and their 6.5-300.

 

[rifleman762]

Why not a 100gr in the 243 for comparison? 1/10 twist shoot those just fine as well.

1300 ft lbs for a 100gr BTSP at 300 yards. Hey, 243 works. I have one... But 6mm CM is a notch better. No one ever said that the Creedmoor is a quantum leap. At least I haven't. But it isn't worse by any measure.