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A:4340 is about 10% stronger than 4140, because of a higher nickle content.
4340 is about 40% stronger than 1040 and about 25% stronger than 1050.
1541h is about 25% stronger than 1040.
The sequence is: 1040, 1050, 1541h, 4140 and 4340.
So runninng 4340 axles will work very well for bumping and hopping to get up over rocks as the axle won't twist and break.