I am having a problem keeping a full sight picture with my 7MM Rem. magnum.
The scope is a Leupold and it is set as far to the back on the gun as possible.
I just can' t seem to keep the scope from blacking out. My only two ideas are that the scope is mounted too low, or the stock needs to be cut down a little. Any suggestions????

You might have to get offset rings to allow the scope to come further back .We just had to do that on a couple of rifles .

Your scope is either too far back or too far forward for the eye relief it has. The extension rings are probably the needed solution, so you can set it correctly fore and aft. It should have a useful range, say from 3" to 4.5" , etc. These specs are available from Leupold, on-line I believe.