I have a Rem 7400 in 243 that I haven't shot in a few years. Took it out and first shot was dead on at 100yrds the rest were all over the place. Decided to try another scope on it, put an old Redfield scope and tried it. Groups were better but ran out of upwards adjustment before I got it were it needed to be.
Put a new Vortex 4x12 on it and got good groups but again ran out of upwards adjustment. Its dead center at 100yrds but cannot raise it anymore and I really like top have it at 11/2" high at 100yrds.
I have see through mounts and rings on this gun.
If I put different bases and rings putting the scope lower on the gun would this give me more upward adjustment.
Any other Ideas on what is going on would be appreciated.

Its been over 15 years since I have mounted a 7400 so I am a bit rusty.

It seems to me that on the 742 or the 7400 can't remember which that the front and or rear bases were the same hole spacing but one of the mounts was taller than the other. It almost sounds like you have them backwards. Try switching the front to the rear and see if that gets you the adjustment you need.

If that does not work I would defiantly suggest going to a solid one piece base and traditional rings. Mounting the scopes bell as close to the bore axis is ideal. A credit cards width is about perfect. Anything over 1/8 of a inch is really a waste.

I agree, check that your bases are on correctly and everything is torqued to the correct spec.

I'd lose the see-thru mounts and put on a pic / weaver style base and decent rings.