Home Forums Hunting & Shooting Ask The Gunwriters Finn Aagaard on the 7x57

You're correct.

Good point!

Good hunting,
John

They are not exactly "my" rules, though I did come up with the basic formula after analyzing published, pressure-tested data. Instead they're a basic reflection of internal-ballistic physics, analyzed by crunching the numbers published in dozens of sources of pressure-tested handloading data.

That said, one of the nifty things about handloading is we can put together cartridges that result in whatever velocity we want. And chronographs are useful in that quest, as part of the big picture--if you know how to use them in that role. Which I have also explained (and demonstrated) in a lot of my published writing.

If bullet/bore diameter didn't matter in rifle cartridges of the same size, then the .243 Winchester would be capable of getting the same velocities as the 7mm-08 with the same bullet weights, when loaded to the same pressure. It isn't--and the difference in bore area (not diameter) between the .243 and 7mm-08 is similar to the difference in bore area between the 7x57 and 8x57.

My off the cuff calc with 28" bbl is that the 8x57 gives about .085 (%) more bore area than same length bbl in 7x57. Maybe some day maybe I will calc if that actually yields the additional 200 ft/sec.

For those who asked/wondered: John's old Serengeti weighs 8lbs, 0.5 oz, including M8 4x in Talley LWs, on my postal scale. The barrel length is 21 inches, as he's mentioned before. I didn't measure the twist but he's mentioned as well that it is 1:9. I put an inverted Hornady Interlock FB in a Hornady modified case and measured the OAL: 2.290 inches. Below is a picture. If standard case length is 2.235 and the SAAMI chamber length is 2.255, then the throat is either .055 or .035 inches, depending on which measurement one uses. That's considerably than the .250 inch throat in my Featherweight or the almost .5 inch throat in my M98.

Serengeti weight:


OAL w/Interlock FB:


Inverted Interlock w/case: