Here is a quote from an older WW Super ammo box, happens to be 300H&H but all were the same. The older "white box" ammo.
"WARNING Use only in Winchester and other standard arms in good condition designed and chambered by gun manufacturer for this caliber ammunition and so marked on the gun barrel."
So what is correct, chamber or caliber.............
Thinking about this I guess that perhaps using the same caliber ammo would cause less problems than the wrong caliber.. Or maybe not.
