Home Forums Reloading Big Game Rifles Case capacity differences between the 7-08 and the 7x57

52.2 grs of water for the 7-08 and 55.6 grs for the 7x57, the 7-08 being Remington brass and the 7x57 being W-W according to Chuck Hawks. How does this translate into how much more of the same powder I can use in the 7x57? This spread is 3.4 grains but the two cases differ a bit more when you consider the 7-08 generally has it's bullets take up more space due to seating constraints in the short action compared to say a Mauser actioned 7x57. My usual rule of thumb is measure the amount powder that each case can hold and use 1/2 the difference as a benchmark. So suppose the water value listed was the powder I am going to use I would add 1.6 grains in the larger case and work up or down from there.

Yes, the 7X57 can get some more velocity. The difference is pressure. the 7-08 has a higher pressure rating. depends on the 7X57 is it modern or an old one. Kinda like the 6.5X55 and the Creedmoor or 260 Remington, pressure ratings. More powder is not a bad thing nor is a longer magazine for COL.

With a model 98 Mauser in good shape and good brass I feel the 7x57 should be able to use the same pressures the 7-08 can and I have been doing it for years.

Nosler on-line data gives figures for case capacity for the 7mm-08 and the 7X57 with the same bullets.

I often use 7mm-08 data for loading for my 7X57 (built on a M98 action with a fairly long throat) for powders that I can't find any 7X57 data for but there is data for the 7mm-08. Then I work up with a little more powder until I reach book values in velocity for the 7mm-08 in my 7X57 while watching my chronograph and how my rifle acts.

My current load for 140 grain partitions with Big Game powder was developed that way.

If its speed you want in your 7x57 I can strongly suggest loading 120gr barnes with Varget. I loaded quite a mild load and got 2950fps from the ttsx. My wife shot a Impala with it last year. Was standing quartering to her, bullet broke the front right shoulder and went the full lenght of the animal, exited leaving a big hole on the left back leg. Excellent performance I was not expecting from such a light bullet.

Actually I am going to test the 130 gr. Speer HotCor in water jugs and just want to easily reach 2850 fps with it. Going to use Imr4895 to do it. I have the early version in the old yellow box and the new more streamlined version from black boxes. Test results to come.

My 7x57s are European made and carry a long throat. Seating 154gr Hornady SP one caliber length into the neck, they leave a case capacity which is roughly 15% greater than a 7-08 at largest COL possible.
Which should allow for, roughly, 100 fps higher muzzle speed at same/similar pressures.
This translates into 3,050 fps for 120gr bullets, 2,900 fps for 139-140s, and 2,700 fps for 160s,

I have always liked my 7x57 having used it extensively since 1993 until I semi retired it a couple years ago. I mostly loaded to 2600 fps using the 150 gr. Ballistic Tip. The throat on my rifle allows me to load most bullets to 3.160 OAL depending on ogive.

Ken Waters compared the 7x57 to the 7mm-08 in his articles in Pet Loads. He was unable to surpass 7mm-08 velocities with similar bullets in his 7x57. There is not a lot of difference in case capacity.

Ken Waters used case expansion of commercial ammo as the limit for his handloads. Ammo for the 7x57 was loaded at a much lower pressure than theat of the 7-08. So it is not surprising he could not exceed 7-08`s velocity given that he was loading ata a much lower pressure.
Not comparable, in other words.
At the same pressure, the larger capacity cartridge, in this case the 7x57, will deliver higher speeds.