I've looked at some specs for both of these but have not seen loads for the 25-08. Can anyone give me some idea of how, or if, these two are different. I'd like to get a better idea how they perform.

Which of them is more powerful? I'm not asking because I want more power, that's what the 25-06 is for. I just wonder if one is inherently better than the other.

And, is there any chance a 25-08 will ever become a factory round? Then we'd have 243, 257, 264 and 284 caliber standards based on the 308.

The .257 Roberts and 6mm Remington cases are both necked down from the 7x57 Mauser. Performance wise, there would be little or no difference between a .257 Roberts and a .25-08 provided both are loaded to the same pressure levels. You can say the same about the 7x57 and 7mm-08, and also the .243 Winchester and 6mm Remington.

The .257 Roberts is a factory round, the .25-08 a wildcat. I doubt if the .25-08 will ever become a factory round. It is also called the .25 Souper. The improved .25-08 is called the .257 Durham Jet.

The best way to go would be a .257 Roberts Improved if you want something a little better than the .257 Roberts. Lots of users and information out there on the Improved version! Good Luck

To me the difference mainly would be that the Souper would fit a bit better in short actions.

Just my thoughts....

"GET TO THE HILL"

Dogz

Academically this posting is similar to comparing a 260 Remington and a 6.5 x 57, both of which I shoot. I use necked down Winchester brass for the 260, and Necked up 257 Roberts Winchester Brass for the 6.5 x 57.
( I prefer Winchester Brass over Remington and Federal).

This question hit me one evening at the reload bench. I took H 380 powder and filled the Necked down 7/08 case with powder, until it was flush with the top. I did the same thing with the Necked up 257 Roberts case.

I then did the same thing with H 414. Most reloaders should be familiar with both powders and their composition.

The 308 sized case held one less grain of powder that the 57mm case did in both instances.

Just passing on the information, so draw your own conclusions. However, the difference is non existant in the real world, at least using Winchester brass in these two case sizes.


[ 10-04-2003, 08:38: Message edited by: seafire/ B17G ]

Seafire: Are both measurments taken with fired, unsized brass? This would give you a true comparison of the actual chamber capacities. Of course, if your .260 is a factory chamber, factory chambers are notoriously oversized, so the comparison with a custom-chambered wildcat (which usually is dimensioned to minimum dimensions) may be misleading.

My mind is too old and hazy to do the geometry required to calculate the capacity difference between the .308-series case and the 57mm series just from the spec drawings, but I think it is nominally more than a grain.

Stonecreek,
On similar cases we may roughly assume that volume is proportional to legth (volume of a cylinder IS proportional to its legth).
Being the 57mm case almost 12% longer its capacity, measured in terms of volume, would have to be around 12% more.
All other things being equal, you may expect more than 1 grain difference.
An unfired case, with very thick brass in 6,5x57 may have one grain difference (maybe less) if you compare its capacity with a .260rem case fired in a sloopy chamber and with very thin brass.
montero

Gonzo,

I have shot a lot of .243 Win (target rifle) and 6mm Rem (hunting rifle). You get more velocity from the 57 mm long case than the shorter 51 mm case, and the 57 mm case has a longer neck (at least with my cartridges, I don't know the relative comparison with the .25-08).

I like Win .257 Roberts brass for 6mm Rem too. It weighs less than the competition, hence more powder room. I burned a lot of Norma MRP in that 6mm, and still do.

jim dodd

Well, not exactly, Montero. The .308 case has less body taper and a shorter neck than the 57mm case, so it holds more powder per unit of length. The differece in capacity is therefore much less than the proportional difference in the length, but the 57mm case still has a larger volume.

When the 57mm case is "improved" with less taper and a sharper shoulder (.257 Ackley for example), the difference in it and the .308 case is somewhat greater and more proportional to body length.

Unlike most of the rounds in the 308 family, those in the 57mm family differ noticeably in dimension (beyond neck diameter). For example, the 6mm and 257 differ in shoulder angle; the 8x57 and 7x57 differ in taper and shoulder position; the 6.5x57 and the 257 differ in shoulder position and shoulder angle.

Anyway, I got interested in the same H414 experiment. Here's what I got:

6.5x57 (necked down 7x57), Win brass: 60 gr.
257 Roberts , Rem. brass: 57 gr.
7x57, Fed brass: 57 gr.
7mm-08, Rem. brass: 54.5 gr.

All are in custom chambers except the 7mm-08. All are fired cases. All are about what I'd expect except, perhaps, for the fact that the 257 and 7x57 are the same. This is perhaps due to the lighter weight of the Rem. 257 brass (thinner walls), which gives it more capacity.

While the 7mm-08 and 7x57 differ by only 2.5 grains - there is still the issue of effective powder capacity due to bullet displacement. This gives the 7x57 a bit more of an edge. The difference is somewhat more pronouced between the 260 and the 6.5x57 given the latter's larger powder capacity (at least 5.5 grains) and the longer throat.

Stonecreek,

out of curiosity I checked out the total case volume as measured in Ken Howell's book and this is what I got:

.260rem- 76gr of water
6,5x57- 82gr of water, or 8% more

I would expect a larger difference in usable case capacity due to the long throat which is standard in the 6.5, pretty much in line with 9,3x62 comments.

montero

You guys are going about this the wrong way.

Montero, those are not case capacity figures.
That is how much water is displaced by the case, i.e., turn the case into a solid mass, build a case around IT, then measure the second cases capacity.
And even as a comparison figure between two cases, it doesn't take into account differences in wall thickness.
Better to ignore those number throughout the book.

Also, the Roberts gets its edge capacity-wise from a loong neck. This doesn't count. You have to look at the useable powder capacity.

So, according to RCBS.load, the water capacity of the Bob is 54.4g, and a case I made up for the 25-08 (called 6.5mm-260, just to be abrasive) measured 52g even.
Put a bullet in them both, seated the same, and the 25-08 comes out on top by about 5g! This is because the Bob has LOTS of neck, which counts in case capacity, but not powder room.

NOW, chamber the Bob in an action that'll let you go to 3.07" (like a short Mauser or SA M70) and the powder capacities are pretty much dead-on.
But for this to still give you a caliber's length seated in the case means you can't use a bullet longer than about 1.1" (which, given the general shortness of .257" bullets should be no problem, unless you like heaviest-weight copper bullets.)
"But you could chamber the 25-08 for the xame COL and keep the capacity advantage!" Well, the case is shorter, so you can't reach out as far away from the base, so it doesn't work like that.
Not enough to sway me either way in and of itself.

I'd be willing to bet we won't see a 25-08 factory in my lifetime (of which there's hopefully plenty left!)
The bore is not all that pop, what with the availability of .264" bullets and the fact that the .243 Win matches the Bob in like-weights and has almost twice as many weights to choose from.
Add to that the magnum craze that's been going on for the last 40 years, and it just seems unlikely.

(Anyone know if that .243 WSSM will feed in an AR?)

Thank you for your post, Bwana-be.

I do know those are not case capacity figures and that is why I did not say they were using, instead, the terms "...total case volume as measured in Ken Howell's..."

I nevertheless consider it the only way to provide a fair comparison between two cases since it locks (caeteris paribus) all other variables such as the wall thicknes that you mention.

On the other hand I would not dare to ignore the numbers through this book since there is an extremely clear explanation on the way those numbers are worked out, which is not always the case in other publications I am familiar with.

A standandard 6,5x57 case loaded for a standard 6,5x57 rifle with a 6,5x57 standard chamber will always have more usable case capacity than the standard, standard, standard .260 rem combination.

I think.

Regards,

montero