6.5mm - 25cal = .007"

[FEENIX]

Exactly ️The fad is for heavies in all calibers. Most do not shoot near far enough to utilize the BC of the heavy for caliber bullet which doesn't come into effect until ranges get past 500 yards.

LL! This site was founded for exactly that: long-range hunting to 1000Y and ELR past 1000Y. It boils down to personal choice and intended purpose. "I" chose to shoot 131 BJ, 134 Hornady ELD-M, Berger 133/135, 145 BH, and now 163 CC for exactly what you noted, beyond 500Y.

 

[Varmiter71]

The main thing is keeping the bullet above the minimum expansion velocity.
And if you take the creedmoor case in every caliber with a bullet of the same bc the smaller caliber will always be faster.

 

[RichCoyle]

My brother-in-law called me "weird Richard". Maybe I am still weird.

My caliber of choice is 7mm. My bullet of choice is a light weight HHT 132 grainer. Long range for me is 600 yards.

It's been about forty years since gave heavy for caliber any thought.

 

[Mach 1]

GM paid back the incentive 14 years ago…that being said…advertising, profit and a consumer demand for the latest and greatest are the factors pushing out all these new or not so new caliber and cartridges to fill so called niches. None are necessary but they sell more guns and ammunition. I agree with you on the creedmore cartridges.

bs they paid back the taxpayer. look up what and how they "paid back" the tax money they took and you'll see that they are far from paid up.

 

[Mach 1]

mono bullets are not solids

mono= monolithic. made up from one solid material.

 

[cdherman]

I did NOT read all 15 pages. But I can say this, which perhaps has already been said, but here goes.

Ever notice that BC seems worse and worse the smaller diameter the projectile is? Even though we have some crazy long 6.5 (.264) heavy projectiles, they trail the .284 heaviest offerings in terms of BC. And in turn, there are .308 that outshine the .284, and .338 that are just crazy.

Why? Because we do NOT tend to shoot monolithic bullets long range. We shoot lead core, copper jacket. And therein lies the problem. As the bullet diameter gets smaller, the relative proportion of the bullets weight that is derived from the less dense copper goes up. This is assuming the copper jacket remains the same thickness, which is generally a necessity in a hunting bullet.

We all know that copper monolithic bullets have a poorer BC that a same weight lead/copper bullet. Cause the copper is less dense and thus there is more surface area and drag.

As bullets get smaller and smaller diameter wise, their density suffers because they are proportionally more and more copper and not lead. You just will never get a .223 bullet that can match the BC of .264. And for that matter, even though .257 is very close to .264, you are giving up a bit of BC.

Practically, I think .264 is the sweet spot for practical hunting long ranges on deer sized game.

 

[Bullwhacker]

I've been playing with a 25 PRC for the past year and can't find anything I don't like about it. 133 Berger's at 3280 fps is a great combination for long range hunting.

 

[ButterBean]

mono bullets are not solids

I've got some bab news for ya

 

[ButterBean]

I did NOT read all 15 pages. But I can say this, which perhaps has already been said, but here goes.

Ever notice that BC seems worse and worse the smaller diameter the projectile is? Even though we have some crazy long 6.5 (.264) heavy projectiles, they trail the .284 heaviest offerings in terms of BC. And in turn, there are .308 that outshine the .284, and .338 that are just crazy.

Why? Because we do NOT tend to shoot monolithic bullets long range. We shoot lead core, copper jacket. And therein lies the problem. As the bullet diameter gets smaller, the relative proportion of the bullets weight that is derived from the less dense copper goes up. This is assuming the copper jacket remains the same thickness, which is generally a necessity in a hunting bullet.

We all know that copper monolithic bullets have a poorer BC that a same weight lead/copper bullet. Cause the copper is less dense and thus there is more surface area and drag.

As bullets get smaller and smaller diameter wise, their density suffers because they are proportionally more and more copper and not lead. You just will never get a .223 bullet that can match the BC of .264. And for that matter, even though .257 is very close to .264, you are giving up a bit of BC.

Practically, I think .264 is the sweet spot for practical hunting long ranges on deer sized game.

Folks shooting the King of 2 mile competition use copper monos I do believe

 

[ImBillT]

If I were starting from scratch, I'd pick 25 cal over 6mm or 6.5 for a short action cartridge. If you compare using modern bullets, there are advantages on both ends of the ballistic spectrum - in velocity and in BC. Here's a quick comparison for reference:

View attachment 558998

I used conservative velocities here, at 5000ft elevation, 50 degrees, 60% humidity, 30.01Hg

It requires a 3000 fps MV (6.5 PRC speeds) from the 6.5 to have similar energy to the 135 Hyb in 25 Creedmoor.

Increasing bore diameter slightly increases efficiency, so a 6.5Creed should shoot a 135gr bullet to a slightly higher velocity than the 25 Creed. That makes me wonder if it's actually fair to compare the 6.5Creed at a full 100fps disadvantage to the 25Creed with only a 5gr increase in bullet weight.

I think a 135 LRH vs a 144 LRH is a more fair comparison because the the bullet design is the same. The 140 Hybrid doesn't have the ogive pointed like the 135 and 144 LRH's. At a 50fps disadvantage the 6.5Creed beats the 25creed by over 100ft*lbs at 1000yds, and at a 100fps disadvantage it still beats the 25creed by 15ft*lbs.

 

[lancetkenyon]

Couple of interesting .257's will be making their debut soon.
Wonderful combination of capacity, efficiency and performance.
Of course they have 40 degree shoulders, like most of the awesome ones.

Do tell...

 

[Phil Rizzo]

I should've said 3 actually.
I only get to play with 1 of them.
2 for you!

 

[vhr1079]

Increasing bore diameter slightly increases efficiency, so a 6.5Creed should shoot a 135gr bullet to a slightly higher velocity than the 25 Creed. That makes me wonder if it's actually fair to compare the 6.5Creed at a full 100fps disadvantage to the 25Creed with only a 5gr increase in bullet weight.

I think a 135 LRH vs a 144 LRH is a more fair comparison because the the bullet design is the same. The 140 Hybrid doesn't have the ogive pointed like the 135 and 144 LRH's. At a 50fps disadvantage the 6.5Creed beats the 25creed by over 100ft*lbs at 1000yds, and at a 100fps disadvantage it still beats the 25creed by 15ft*lbs.

We are really splitting hairs at this point, but there is a definite velocity advantage for the 135s and they are nearly the exact same BC as the 144 lrht in 6.5. My numbers are not lining up with yours, and the (tiny) advantage still goes to the 25 in terms of recoil and wind drift, in my opinion. There is no discernible difference for any game animal between these two, but it's still fun to compare.

25 CM - 135

6.5 CM - 144

 

[ImBillT]

We are really splitting hairs at this point, but there is a definite velocity advantage for the 135s and they are nearly the exact same BC as the 144 lrht in 6.5. My numbers are not lining up with yours, and the (tiny) advantage still goes to the 25 in terms or recoil and wind drift, in my opinion. There is no discernible difference for any game animal between these two, but it's still fun to compare.

25 CM
View attachment 562663
6.5 CM
View attachment 562665

Even your original was splitting hairs, but it was comparing two bullets of different design, with advantages in favor of the .25, and what is likely excess velocity advantage to the .25 as well. I wish there was a comparable 135gr 6.5mm to compare to the .25. Then you could plug in the same velocity for each and at least be close. The .25 would have a slight BC advantage over the 6.5 if they were the same weight. To be perfectly accurate the 6.5 would have a slight velocity advantage. Honestly that's the issue. SLIGHT. It's only .007". With same weight bullets, the .25 should manage a SLIGHT BC advantage, and the 6.5 should manage a SLIGHT velocity advantage. With same BC bullets, the 6.5 will recoil SLIGHTLY more and have SLIGHTLY less muzzle velocity, but SLIGHTLY more energy and momentum. There's no magic to .257" bullets or to .264" bullets, and both are so close that it's hard to say that one fits in a certain action or even cartridge better than the other.