Just trying to confirm my thoughts on this, together with the change I'm going to make.

Current rifle configuration is a Christensen Arms Ridgeline in 7mm Magnum, 26 inch barrel with a CA 20 moa base, (Talley), and a Swarovski Z-5 5x25 52mm BT with the 4W reticle. Rings are medium height.

I currently cannot get the rifle to shoot any lower than 2 inches above the bull with the scope turned all way down on elevation. Essentially bottomed out.
I'm thinking replacing the base with a standard height base will give me the ability to sight the rifle dead on at 100 yards as I will have the 20 moa adjustment downward to play with.

Reasons?  One, my sight-in range is 100 yards, although I do have a 600 yard steel target practice range also available.  Two I have a replacement custom engraved turret for the scope and my hunting load that will allow me to dial from 100 to 700 yards in elevation.  (These are pretty much my minimum and maximum practical hunting ranges)

Thoughts?  I am on the right track here?

Your scope spec sheet says it has 43 MOA of vertical elevation available, so divide by two and you would have 21.5 MOA of downward elevation adjustment. The scope must have slightly less than that in actuality, because instead of being about 1/2" inch high, it's 2" high.

If you're not using turrets to dial your firing solution and instead you are using the reticle to make holdovers, you don't need the extra elevation adjustment afforded by the 20 MOA base. In that case, your zero will be where the gun always shoots.

In short, yes a 0 MOA base solves your problem. Just to be sure, your scope has traditional low profile hunting turrets, and not the adjustable kind you see on tactical scopes, right?

If your scope has the low pro turrets and you substitute one of those for a tactical style one, you might find it doesn't track great when dialing elevation in and out, repeatedly. The erector assembly (the guts) is often not designed for repeated input on hunting scopes.

7mag is pretty flat shooting and you may be best off with a 0 MOA base, and inputting your holdover only with the reticle.

This scope has what Swarovski calls a Ballistic Turret or "BT" in the model designation.  As supplied from the factory, there are three rings on the elevation turret that are set at your zero range- a red dot on the ring and then you have two additional rings you can set to elevations of your choosing.  The custom turret is calculated and laser engraved to provide specific elevation settings from sight-in zero for the velocity, weight, B.C. and altitude.  In theory, the replacement turret has enough elevation from a 100 yard zero to accomplish the 700 yard adjustment.  Outdoorsmans is one offering- Custom Turret
We will see what actual results will yield..
Thanks for the responses!

Maybe I'm tired but since a 20moa base is sloped forward wouldn't switching to the flat base raise POI?

It's been a long day

Only if you have it mounted backwards.