So...where published in any reloading manual is there reliable data that would allow the 7x57 to perform as it should perform in modern firearms like the CZ or Ruger?
The text in my Speer manual #13 states that their listed maximum loads for the 7x57 are only to be fired in modern firearms or Mauser 98s in good condition (their test rifle was a Ruger M77). They also say to NOT fire the maximum loads in Mauser 93s and 95s, and not to exceed the starting loads in those rifles. IIRC, it says the industry maximum pressure for the 7x57 is 46kCUP, whereas their maximum listed loads operate at a maximum of 50kCUP. Is this not modern loading data? The loads purported previously in this thread are WAY above the maximum loads in Speer #13. I may exceed Speer's maximum 7x57 loads a little bit in my modern Ruger rifles, but not to the level purported in this thread.
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The loads I reported from the friend of mine in her book are her loads, fired in a Steyr Professional. I also reported loads that my father loaded for my brother's Ruger (Tang Safety).
Those of you that have not read JB's article on the 7x57, and the loading there of, really should. It's not only a very good peice on the 7x57, but if you really read and understand how he works up loads for the 7x57 it will give all you "never exceed max listed loads" guys some new insight on handloading developing of loads. Its the way I've always developed loads for all my guns. The "max listed load" changes from data source to data source. The expected safe velocity/pressure level for a given burn rate of powder/bullet wt./bbl length is much more consistent. Loaded to the same pressure levels, a 7x57 with its higher powder capacity, will out run a 7-08.
To compare apples to apples from the Alliant reloading site:
7x57, 24" bbl: 160Sptz BT, 49grs R-19, 2665 at 45.5K psi.
7x57, 24" bbl: 139 SP, 51.8grs R-19, 2835fps at 49K psi.
7-08, 24" bbl: 160Sptz BT, 48.5grs R-19, 2675 at 56.7K psi.
7-08, 24" bbl: 139 SP, 52grs R-19, 2850fps at 57.9K psi
The 7x57 runs virtually the same velocity at 9K-11K psi less pressure. The same actions being used for rounds such as the 270, 280, 30-06, etc running 60K-65K psi will handle the 7x57 running at similar pressures. It's not hard to see how the data in this thread is within those modern, but safe pressure limits. I know from looking at QL data for my .280Rem, that a 10K increase in pressure fron the low 50K's to the low 60Ks is good for about 100-120fps with powders like R-19 and others similar in burn rate. So, it wouldn't be unreasonble to assume nearly that same gain by loading the 7x57 up to @57-60K psi. Which would put that 160gr load up around the mid 2700s and still well under 60K psi. Likewise the 139 at @ 2950 right at 60K psi. I've watched my dad and brother put more than a few 139s/140s down range from a 22" Ruger 7x57 at 2950+fps with no problems and good brass life. I know the lady that I posted about, and her husband that loads for her. He's very experienced and knowledgable in loading and shooting. She's used that gun and those loads for over 2 decades to take countless heads of game. No problemo!
In her gun, I'll trust they must safe.
