How do you adjust a rifle scope mount for elevation if I can't get enough adjustment out of the scope adustment?

You could try using shims or getting higher rings.

I used shims to put on the inside of the scope rings and it worked very well for me. Black electrical tape works also. But, will have to re-check for movement and settling.

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You might also check that front and rear mounts are not reversed. Some are higher at one end than others to account for a slope in the firearm, etc.