Home Forums Hunting & Shooting Hunting Rifles 6.5's by the numbers

I appreciate your reply, however this is not at all what I proposed. What you describe is an even _larger_ case, loaded to the normal CIP pressure limit of 3800 bar. People here are hypothesizing (likely correctly, but 'show me the data...') about how their favorite 'coulda bina contenda' if they'd just be allowed to over-pressure it until it goes as fast as the neighbor's cartridge. While again I agree that the premise is basically sound, you don't get to compare speeds at unknown/daydream pressures.

All that said, I cannot find a 6.5x55 SKAN in CIP's data files. I _can_ find an Italian-origin (according to CIP) cartridge they call the 6,5x55 T.R.I. It appears to be what you describe, but it also has a 5mm longer COAL. So, it's sort of a 6.5x55AI built for an '06-length COAL. Of _course_ that will run faster than a 6.5x55 Swede!

Here are the links to the CIP cartridge drawings for the Swede and the T.R.I. cartridges:

http://www.cip-bobp.org/homologation/uploads/tdcc/tab-i/6-5-x-55-t.pdf

http://www.cip-bobp.org/homologation/uploads/tdcc/tab-i/6-5-x-55-se-en.pdf

Unfortunately, at this moment there is only a German file for the T.R.I., but it's easy to see the dimensional differences.

I'm happy to add the weatherby or PRC when they exist somewhere besides Al Gores Internet... I need to fix the action length on the 6.5x55 also... cut and paste typo.

;]

Again these are rounded numbers that are based on widely published factory loads. Your 38" wondertube loaded 15% over SAAMI can surely beat it, and no 18" factory pencil barrelled carbine will touch it.

Also some cartridge pressure curves are capped by the era in whch they were created and the structural integrity of the rifles. Loading a 6.5x55 to 6.5 creedmoor pressures might be fine in a Remington 700 or Winchester M-70, but those pressures wouldn't be kosher in a gun built in 1890 or whenever it was created. That is where SAAMI puts the pressure limit, on the lowest common denominator. You go over that in any platform, you do so on your own...

It is what it is, just here for comparison for those wondering how these new (or newly popularized) cartridges compare...

...or to realize that they for the most part are the same

:]

I like it. It's a good comparison, and indeed clearly shows how crowded the space presently is!

MZ5,

The difference in case capacity between the 6.5x55 SKAN and "standard" 6.5x55 is so small that a few grains difference in case weight would switch their capacity. The difference in length from the case head to the shoulder is only .006 inch, and all the other body measurements are exactly the same, including the shoulder angle. So it is not an "even larger case."

Hodgdon 2016 Annual Manual RELOADING data.

ALL loads in 24" barrels, max fps/loads used in each caliber.

6.5 Creedmoor 142 gr. Sierra HPBT 2737 FPS @ 57,100 PSI

260 Remington 142 gr. Sierra HPBT 2747 FPS @ 58,700 PSI

6.5x55 Swe.Mau. 142 gr. Sierra HPBT 2725 FPS @ 46,100 CUP


The poor old Swede seems to be keeping up..and that pressure is for the older M96 action too.

NOSLER Load Data from their website:

6.5 Creedmoor 24" barrel Max load 140-142 gr. 2731 FPS.

260 Remington 24" barrel Max Load 140-142 gr. 2830 FPS.

6.5x55 Swede 23" barrel max Load 140 142 gr. 2790 FPS.
(add 1" to the swede barrel and gain 20 fps.)

Fair enough. I still can't find that case anywhere but Viht's website. CIP only has the Italian one I linked to with the longer COAL. It also has a different shoulder angle. In fairness, the COAL alone makes it an "even larger case."

So, does anyone but Viht acknowledge the SKAN?

Norma's manual shows just one 6.5x55, and loads it to CIP spec of 3800 bar. Their data shows it to be about as much slower than the 260 (with the same 140-class bullets) as the 260 is slower than the 6.5-284 Norma.

MZ5,

It is not a question of the capabilities of the 6.5 swede cartridge at max pressures, but what liability industry is willing to take in publishing those loads with regard to older/weaker actions that those max loads potentially could be used in.

The 260 rem., creed. and swede are all within a few grains of capacity with the swede having the highest, so will have the higher velocities(albeit by just a scoche) of the three, at the same pressures.

One thing is for sure......

The 260 and the 6.5 creedmoor will both do what the 6.5 swede has been doing for 120 years now!



Trystan

MZ5,

Do you comprehend that physically the case with larger capacity always has more velocity potential when loaded to equal pressures?

No further testing would be required to "prove" this, since it is based on the laws of physics.

Plus, they'll do it in a shorter action.

I just picked one up from Sportsman's for $299.

Not in a Tikka... in which case I'd do the 6.5x55. Bigger engine.

That's what I paid for mine a few weeks back. Can't hardly say 'no' to that!

"One size fits all" actions aren't my cup of tea, therefore no Tikkas.

I think that all of my short action cartridge in long action rifle are all Husqvarnas, Mausers, and Winchesters.

I concur. I'd not own a Tikka, but they're very popular.

Me, I'm more a SA guy, and to me the 6.5's are all about SA's, or in the case of the 6.5x55, a "mid-sized" Mauser-type action. If I want something in a LA I'm going to a bigger caliber than 6.5.

I don't "get" LA 6.5mm Magnums.

Of course. Did you not see that I have said as much in this thread? That's not the issue. The issue is people taking the general theory and trying to apply it to specific circumstances without any way to test or validate the application of their hypothesis in the specific circumstance. There are at least 2 things that jump immediately to my mind that, in this instance, might allow the imaginings to be exactly true, or might make them impossible.

I've tested quite a few of these sorts of hypotheses myself, using my Pressure Trace. What I've found is that they're rarely to never what they're claimed to be. That doesn't mean they _can't_ be real in this instance. It simply means that my experience with hard data tells me one thing: Show me the data.

I am closely acquainted with the people who run two of the major piezo labs, which do the pressure testing for most of the handloading powders sold in the U.S. In answer to question with a slightly different context, they told me a couple of years ago that powder capacity is THE factor in how much velocity in possible in two cases of the same caliber, loaded to the same pressure.

I specifically asked whether they'd ever found any of the magic velocity some cartridge developers claim due to shoulder angle, or how long or short a case might be. The answers from both places were an emphatic no--both adding the detail that the only factor in potential velocity is powder capacity, everything else being equal. The corollary would be that larger capacity does NOT result in less velocity when cases of the same caliber are loaded to the same pressure, regardless of case shape.

Both of those labs have been running "experiments" along those lines for many years, with state of the art pressure equipment.

Yup.

Engine size matters.

Yes, once again, we all agree that the theory is there, even if we gloss over the details that make things unequal.



Respectfully, one of those two labs is apparently ignorant of the ramifications of the differences between the various instrumentation systems, as evidenced by their publication of data at multiple pressure levels for the 223 Rem. They appear to be conflating the instrumentation from one system with the numerical value derived from another.



That's where the potential issue comes from. Things that are different are not the same. To choose a single example of how this always makes things unequal: No one powder is _equally_ optimized for two different-capacity cartridges. This is why ALL data manuals show ALL tested cartridges yielding different speeds for ALL the powders they test in it with a given bullet; no two of the powders is equally optimized for the cartridge-bullet combo.

I recognize that the need to use tested data rather than speculation when making comparisons between cartridges upsets some of the preferred views here. I've said enough in this thread, so carry on with the musings.