<a href="http://s1196.photobucket.com/albums/aa414/gonzok34/300%20Mag/?action=view&current=300winmag2.jpg" target="_blank"><img src="http://i1196.photobucket.com/albums/aa414/gonzok34/300%20Mag/300winmag2.jpg" border="0" alt="gonzok34"></a>
I use both an angle cosine and a level. I shoot in LR military (open sights), LR Metal Shilouette to 600 yard, and metal targets out to 1200 meters, as well as hunt elk and deer with shots out to 800yds successfully.
For the most part the level helps in competition and while practicing. When your shooting in mountainous terrain with steep angles, across ridges, and into shadows. With variable winds coming from different angles. Any slight cant when shooting beyond 600 yds will effect your point of impact considerably.
In Vietnam we did not have the benefit of levels or angle cosine indicators. It took tremendous effort and extensive practice to become proficient. But, in the process we did miss some critical 1st round shots.
Hunting isn't combat. But with the economy and the cost of fuel, we all want to get the most from our dollars spent. Precision shooting is not cheap. Rifles, action tuning, barrel truing, scope bases, rings and NF scopes are a serious investment. Loading several hundred rounds to develop loads and ballistic data is time and money consuming. When you include the cost of out of state big game hunts. You want to make each and every shot count.
Buy the best gear and practice, practice, practice.
Angle Indicators, Levels, Scopes and Custom Built Rifles aren't going to make you a better rifleman. Shooting constructively will.
Gonzo
SEMPER FIDELIS