7-08 vs 7x57

My own experience is limited to .243 and 6mm Rem

My own experience is limited to .243 and 6mm Rem. I had a .243 my wife had a 6mm in otherwise similar Ruger bolt guns. The conventional wisdom which described the 6mm Remington as a .243 Improved was about right. Certainly I loaded them to equivalent pressures as nearly as I could tell by case expansion and performance. The 6mm might take a grain or two more powder but as the conventional wisdom said, the 6mm needed that grain more powder to reach the same pressures.

I'd certainly expect a 7x57 to handle as much pressure as a 7-08 given action for action and brass for brass and throating for throating - that is no free bore which might be an accidental thing with the shorter case.

I'd expect differences between brands of cases might make as much difference as the difference in cartridge external dimensions. That is 7mm-08 cases made from reformed Lake City might be more different from the commercial than some 7X57 is.

But again this speculation based on the 6mm family.

7x57 pressure limits are based on older guns such as Mauser 95, 96 and 98's. Modern guns such as a Ruger can handle more pressure due to better steels and heat treatments, so the 7x57 easily equals and may slightly exceed 7mm-08 ballistics. Of course, even the older rifles chambered in 7x57 using factory ammo have a history of taking just about every game animal on this planet, just not with the lightweight bullets.

I've got a M70 Featherweight in 7x57 Mauser (22" bbl). I push Sierra 140's at 2850fps (Hornady's 140gr LightMagnum duplicates my handloads). If I remember right, Speer 115 HP's leave at about 3000fps.

Ty

We're getting 2716 fps out of factory Remington 140 grain Core-Lokts shot from a 20" 700 ADL 7mm-08 youth model. We haven't tried to soup it up yet with handloads, and we haven't tried to see what we can get out of 120's, either. We are about to start experimenting with 140 grain Triple Shocks, so if you have some time to wait I can let you know. Is this about the Scout project you discussed over at the Campfire?

If my goal is to push a 120 gr bullet at 2800-2900 fps and a 139gr bullet at 2700-2800 fps out a 20" barrel , would it make a difference which round I used?

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The 7mm-08 will have a bit more zip to it, but both rounds will easily push a 120gr bullet to 2900fps and a 139gr to 2700+fps. Even my ol' Chilean '95 Mauser:



Yes, that's the original (s/n matched) military stepped barrel.