Baribal, do you have any information on why all the 1600 series in 7X57 have that 1:12 twist?
http://www.canadiangunnutz.com/foru...7-question?p=12783971&viewfull=1#post12783971
Ted
There is no official explanation for this, other than the Swedes didn't use the 7X57 much, as they already had the 6.5X55 for long, streamlined bullets. As a result, the most common loadings in the days for the 7X57 were RN bullets and often of the 150-ish grains weight and less, so very short bullets. Even in the '50s, the American writers were wondering why they did that and they came to same conclusions.
The .30 calibers were also made with 1:12" twist...
The mentality in Sweden have long been to use RN bullets almost exclusively in any calibers for big game hunting and looking at old Norma Catalogs make it even clearer.
Here are the fuigures;
.30 calibers; 1:12" 4 lands and grooves
.243 - .270; 1:10" 4 lands and grooves
6.5X55 ; 1:8" (1:200mm actually) 4 lands and grooves
7mm RM; 1:9" 6 lands, 6 grooves
.358 NM ; 1:12" 6 lands and grooves.
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