"...over long distances..." What do you call long distances for hunting? Are you using factory ammo or reloading? What bullet? How far have you ever shot? Have you looked at the ballistics of the 7mm mag? The highest energy at 500 yards using Remington factory ammo comes with 150 grain Scirocco™ Bonded bullets. 1704 ft-lbs. However, when sighted in at 200 yards, it drops 34" out at 500 yards. It drops like a brick between 300 and 400 too. About a foot.
High magnification scopes come with weaknesses. The higher the magnification, the smaller the field of view(FOV) is. A Burris Signature 8-32X, for example, has a FOV of 4.5 feet at 100 yards. A Nikon Monarch 6-24x50 has an FOV of 4.2 feet at 100. Both on maximum magnification and both will be much smaller at 1,000.
"...for target competition..." Not all matches allow a magnum of any kind. Limits the matches you can shoot with a 7mm. Plus if you're not reloading, you won't find match grade ammo in 7mm Mag.
There are match grade bullets available for reloaders though. Hornady makes a 162 grain A-Max and Sierra makes a 168 and 175 grain Matchking. Use the 175 grain Matchkings for 1,000 yard target shooting. Cheap they ain't though.
