6.5 CM or 6.5x47 Lapua

Don't overthink it.

Ballistically, they are almost twins. Creedmoor has a little more power to it, making it more suitable for 140 grain projectiles. The 6.5x47L is better suited for 130 grain projectiles. Great option in both projectile weights, for the type of shooting you will be doing there is no practical difference, ballistically, between the two.

Creedmoor most likely has better component availability - though in todays world, the edge goes to anything that you can practically get right now. Perhaps your reloading store is better stocked with 6.5x47L components. What you can feasible get will probably be a big driver in which cartridge you choose.

If you ever want to the ability to shoot factory ammo, then that's a huge advantage to the Creedmoor. However, after starting reloading, I personally haven't found the need for factory 6.5 Creedmoor. As nice as it seems, you may never really need this ability for this barrel.

Enjoy. Both great cartridges that are ballistically twins.
 
Maple57 said:
I'm going to suggest that you asses this question from a fundamental perspective.

If you start by examining the most popular and long standing cartridges used in long range competition you will find a close link between the powder charge and the bullet weight.

Bullets used for long range are inevitably among the heaviest for the caliber. For 223 it will be 80-90 grains, for 6mm it will be from 105 to 115 grains, for 6.5 it will be from 130 to 145 grains.

If we take the bullet weight and divide by 3, you will get a ball park powder charge that is used in most competitive long range cartridges. In this case we are considering the 6.5 mm so 130 / 3 = 43.33 grains and 145 / 3 = 48.333 grains.

So if we are to replicate the most popular and proven long range cartridges, we would want a case that holds between 43.3 and 48.3 grains of powder. That eliminates the 6.5x47 L.

So mathematically, the power to bullet weight ratio leaves us with the 6.5 Creed as the most proven choice.

Besides, the small rifle primer used in the 6.5x47L can cause ridiculous ignition inconsistencies over wide temperature changes that you will not experience with the LRP 6.5 Creed.

In this case the 6.5x47L is a little under powered and in contrast to the 6 Creed which tips the balance in the over powdered direction and is on the hot side of the one third line.
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That’s very informative, I thought the heavier the bullet the lesser powder though
 
ffgats said:
That’s very informative, I thought the heavier the bullet the lesser powder though
Click to expand...

Let's just say some in F open have used the 6.5X47L with heavier bullets and done just fine at 1000yds. There is theory... and there is reality.

Sometimes, you will only know by doing.

Good thing all those FTR shooters launching 200gr bullets don't care much about this 1/3 theory... I would really like to see how you are going to get 66.6gr of powder into a 308Win case. 1000yds qualifies as long range me thinks, sub 1/2 moa is pretty darn precise.

And I have no idea how you are ever going to cram 30grs of powder into a 223 behind a 90gr bullet. I shot whacks of 90gr in 223 for FTR and me no think, 30gr of anything ever got loaded up... and I did really well with my combo.

6Br... pretty sure that is a popular case and definitely used in LR shooting. 105gr to 108gr bullet.... 35 to 36gr of powder? not seeing how this works

F open is dominated by the 284 Win shooting 180gr to 184gr bullets. 60 to 61grs of powder??? you get the idea.

Be nice if a theory could survive a real world test of 1.

I still choose the Creedmoor because for PRS, it is more then just speed and accuracy... if you ask shooters of either the 6.5X47L and Creedmoor what the best shooting loads are using the same powder behind the same bullet... they are going to be within 1gr of each other.

But then maybe I don't understand the theory.

Jerry
 
Mystic Precision said:
Let's just say some in F open have used the 6.5X47L with heavier bullets and done just fine at 1000yds. There is theory... and there is reality.

Sometimes, you will only know by doing.

Good thing all those FTR shooters launching 200gr bullets don't care much about this 1/3 theory... I would really like to see how you are going to get 66.6gr of powder into a 308Win case. 1000yds qualifies as long range me thinks, sub 1/2 moa is pretty darn precise.

And I have no idea how you are ever going to cram 30grs of powder into a 223 behind a 90gr bullet. I shot whacks of 90gr in 223 for FTR and me no think, 30gr of anything ever got loaded up... and I did really well with my combo.

6Br... pretty sure that is a popular case and definitely used in LR shooting. 105gr to 108gr bullet.... 35 to 36gr of powder? not seeing how this works

F open is dominated by the 284 Win shooting 180gr to 184gr bullets. 60 to 61grs of powder??? you get the idea.

Be nice if a theory could survive a real world test of 1.

I still choose the Creedmoor because for PRS, it is more then just speed and accuracy... if you ask shooters of either the 6.5X47L and Creedmoor what the best shooting loads are using the same powder behind the same bullet... they are going to be within 1gr of each other.

But then maybe I don't understand the theory.

Jerry
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You dont read between the lines very well Jerry.

Yes I understand FTR guys are running 200 grain bullets in a 308, but that does not change the fact that the round is not ideally powered. A more ideal 308 caliber round would require in the area of 66.6 grains of powder, which is obviously an open class round.

Will a 308 work with 46 grains of powder? Sure, but it is not "optimal"

Again, you touch on the 223 with 90s... I do it as well but it is not "optimal" it just fits within the FTR rules. Fitting within FTR rules does not equate to "optimal", just optimal within the rule.

30 grains with 90s would certainly be an improvement.
 
I haven't found the rule of three working well for any cartridges from the .222 to the 303.
As far as FTR , f/O, or Palma the rule goes out the window as well

Cat
 
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iron cat said:
I haven't found the rule of three working well for any cartridges from the .222 to the 303.
As far as FTR , f/O, or Palma the rule goes out the window as well

Cat
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The context of this thread is not constrained to FTR or Palma cartridge limitations.

FTR is a specified cartridge limited class, so you are required to use one of two cartridges regardless of where they fit along the Under powered<>ideal<>Over powered range.... The same goes for Palma.

More than anything it applies to open class or 1000 yard bench rest where shooters are free to select whatever they want. Sure you can fart around with a 6 BR at 1000 yards, but that does not make it an ideal cartridge for 1000 yards.

The TOP SHOOTING open class shooters will align very closely.

You may even find some guy using a 222 with 40 grain bullets, but that does not make it ideal.
 
The rule if three doesn't work for the big 1,000 yard benchrest cartridges I am familiar with, nor does it work for my 300 meter Int'l free rifle cartridges . Math obviously isn't my strong point....
Cat
 
Maple57 said:
The context of this thread is not constrained to FTR or Palma cartridge limitations.

FTR is a specified cartridge limited class, so you are required to use one of two cartridges regardless of where they fit along the Under powered<>ideal<>Over powered range.... The same goes for Palma.

More than anything it applies to open class or 1000 yard bench rest where shooters are free to select whatever they want. Sure you can fart around with a 6 BR at 1000 yards, but that does not make it an ideal cartridge for 1000 yards.

The TOP SHOOTING open class shooters will align very closely.

You may even find some guy using a 222 with 40 grain bullets, but that does not make it ideal.
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Maples57,can you telll me where the rule of three was derived from?
Cat
 
iron cat said:
Maples57,can you telll me where the rule of three was derived from?
Cat
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20+ years of shooting F Class... Often.

It's not really a rule as much of a guideline. Obviously people use cartridges on either side of that number with varying degrees of success.

Would you argue that 30 grains of powder behind a 0.224 90 grainer would not perform very well?

Would you argue that 38 grains of powder behind a 0.243 115 grainer would not perform very well?

Would you argue that 47 grains of powder behind a 6.5mm 142 grainer would not perform very well?

Would you argue that 60 grains of powder behind a 7mm 180 grainer would not perform very well?

Would you argue that 73 grains of powder behind a 0.308 220 grainer would not perform very well?
 
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I'm not arguing anything and have been around fullbore and silhouette shooting for quite some time- about 50+ years actually.
What I am saying is it doesn't work for everything and I was wondering where it was derived from .
Cat
 
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