I think you'll find as I have that a well lubed ,cast bullet sized .001 over bore size tends to be consistently more accurate than a bore diam. cast bullet except at very low velocity.
Ive consistently seen better accuracy in my 458 win and 450 marlin with .001 over bore diam. cast gas check bullets

http://www.neihandtools.com/catalog/index.html
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btw I found this bullet to be especially accurate in my marlin 45/70 over 45 grains oF IMR 4198

Last edited by 340mag; 05/14/13.