Can we please stop talking about "flat shooting" cartridges

[Rule 303]

Apples to apples is always really difficult, particularly with the enormous range of loadings, particularly with the 270. Somebody will always argue that selecting 140s for both isn't fair, and the next guy will argue the 130 vs the 140 isn't fair. I just looked at common loadings.

Yes, the 45-70 was absolutely a cover all statement. I tend to avoid absolutes, because there are exceptions to every rule, and most people who use absolutes are absolutely incorrect ;-)

OK. I was thinking along the lines of say 140grn 6.5 against 150gr 270 as opposed to say a 95 Grain 6.5 against a 140grain 270. so for apples to apples I was thinking 1 weight up for the larger bullet. That said a round nose wont hold the velocity like a spitzer.

Correct me if I am wrong but the 6.5 calibre is one of the more ballistically efficient calibres as far as SD goes.

 

[Flewis]

I can see this will be endless.

 

[akrifleman]

OK. I was thinking along the lines of say 140grn 6.5 against 150gr 270 as opposed to say a 95 Grain 6.5 against a 140grain 270. so for apples to apples I was thinking 1 weight up for the larger bullet. That said a round nose wont hold the velocity like a spitzer.

Correct me if I am wrong but the 6.5 calibre is one of the more ballistically efficient calibres as far as SD goes.

All calibers are equally able to be ballistically efficient, but for real world available bullets... yes, the 6.5 has for a long time been more efficient. It would be more fair to compare the 6.8 Western with a 175gr that has a higher BC than even the 6.5 143gr ELD-X for example.

Because almost all of the 270 Win options are in the 130-160 range, and most all of them have a much higher drag function then any Creedmoor/PRC loadings (mostly due to 1 in 10 twist, that won't stabilize high BC bullets).

Where we get subjective now is comparisons... For hunting bullets the 143 ELD-X is the most common 6.5 Creedmoor bullet, and the BEST AVAILABLE 270Win (ballistics wise) is probably the 145 ELD-X (but rarely seen). There the wind drift difference becomes a much closer race (the exception to every rule). Most of the common offerings for the 270 Win are half that (and my reference).

At the end of the day, that is why for external ballistics (we aren't talking terminal performance), the drag function trumps all the things that are diminishing returns. If somebody custom twisted a 270 Win to 1 in 8, and then ran a 175gr bullet... it would flat walk away from the Creed/6.5x55.

 

[Rule 303]

Akrifleman, I see where you are coming from.

 

[wolfhunter]

Many coyotes at 300+ big game longest AK Caribou 250yds 35whelen AK.moose close to 400 we got it it, took some amo to get the job done

 

[Doug Hamilton]

It seems to me that it is a combination of both velocity and BC. Not one or the other.

 

[bobdahunter84]

I know at 400 yds, my 26 nosler has 4" less drop than a 270 win, and is still pushing over 2,000 Ft-lbs

 

[Rule 303]

I know at 400 yds, my 26 nosler has 4" less drop than a 270 win, and is still pushing over 2,000 Ft-lbs

And the 7mm Mag is 2 to 8" less drop than the 270Win depending on which ballistic table you use.

I am not saying the 26Nosler is a slouch by any means, and that is flat shooting in my book, just ballistics can be cherry picked.

 

[woodsman1991]

It seems to me that it is a combination of both velocity and BC. Not one or the other.

You are precisely correct. Both BC and FPS matter, and the distance to target determines which matters more. For example, out to 500 yards there's very few (if any) setups that beat a 300 RUM shooting the Hammer Hunter 124 grain solid copper at 4200 FPS. Zeroed at 300 yards has a max rise of 2.2 inches at 200 yards and only drops 5 inches at 400 yards and 15 inches at 500 yards. Time of flight is barely 1/2 second@ 500. To my mind, this is ideal for any non dangerous game within reasonable hunting range. No need to complicate things and make windage or dial for exact range. Point and shoot once you've accomplished the stocking portion of the hunt.

If the goal is to bang steel at longer range, or for some, to hunt at extended distances, then the calculus shifts towards a slower velocity and a higher BC pretty quickly. As with everything in life, it's all about compromise and having a clear vision of your goals vs the tools at your disposal.

 

[Doug Hamilton]

That is absolutely not true. Wind deflection is purely a product of bullet BC. The cartridge is objectively irrelevant.

Most of the very high velocity cartridges throw extraordinarily poor BC as they were created before such things were ever considered, and do not have the twists or throating for high BC bullets. They may have been better in the wind compared to the previous cartridges of their era, but that ship sailed a long time ago.

Compare a 270 win to a 6.5 creedmoor. The 270 has more velocity and drops less @ 500 yds than the Creedmoor, at double the wind drift. By 600 yds the velocity advantages switches, but the wind drift only widens. Wait!!! I'm not ethically shooting at 500 yds! Fine. At 300 yds what difference does it make then? Nothing drops that much and nothing drifts that much.

Even a 45-70 shoots flat enough at 300 yds to hit anything. If your past 300 then you better be accurate with ranging, and reading and compensating for wind is EVERYTHING.

Wind deflection is a combination of BC and time of flight. The longer a bullet spends between the muzzle and the target the more it is deflected by the wind. TOF is directly related to the initial velocity.

 

[0002S]

To put some numbers to it, here is some info comparing 6.5 CM and PRC using the same bullets. Velocity makes less of a difference on wind drift than you’d expect, not nothing, but surprisingly little. at 500 yards, it’s only a 1.2 inch difference in wind deflection.

From the big game hunting blog.

View attachment 590597

View attachment 590598

‘At 1,000 yards, the 6.5 Creedmoor has about 9″ (~15%) more wind drift than the 6.5 PRC. That’s not nothing, but it’s not a gigantic difference either.

That’s not really surprising though. After all, the two cartridges are using the exact same bullet. So, the difference here is entirely due to the 260fps advantage in muzzle velocity the 6.5 PRC has.‘

No, no real difference at all……

 

[375Ruger416]

LOL - not much difference in wind drift. A 260 fps increase in muzzle velocity should have some difference in trajectory and energy. The effect of a high BC really does dominate.