It's what JOC says he used with 140-grain bullets.
Their choices were limited back then, compared to ours today.
DF
I first started reloading back in the late 1970's. There was a Montgomery Wards store locally that sold some reloading supplies, and I bought a little Lee Loader for my 243. The store had a very limited selection of powder and bullets and the only rifle powder they had that day was IMR3031, which is not really ideal for the 243. I also bought some 75 grain Sierra bullets. The only powder measure I had was the little scoop that came in the loading set, which I found out later measured out extremely mild loads. But, the local groundhogs didn't seem to know that, as it was a very accurate load.
Things have certainly changed.
Nosler online reloading data for the 7x57 shows the 120 grain BT with 47.0 grains of IMR 4320 achieving 3008 fps MV. I tried this load and it was a hot load for sure, but accuracy in my Brno 98 Mauser (Peruvian Army sporterized) was only about 2" inches and it was a hot day at the range; and I suspect that it is a temp sensitive powder. I got a stiff bolt lift at the 46.5 grain load and didn't shoot the heavier 46.8 and 47.0 grain loads.
Nosler also lists a 40 grain load of IMR 4320 40.0 grains behind a 175 PT producing 2480 fps, which I intend to try at a later date, I have 100 factory seconds (Remington 175 grain) enroute from Midway USA and I will work up some loads to test when I get some nice range weather.
But as of late, I have been favoring the temp stabile Hornady powders such as Varget, H4350, etc. for my reloading efforts.
CJ
