Re: Most popular or most common LRH cartridge???
Depends on how far youre talking and how big the critter. If its deer out to 600 yards max the 308 or hot 6mm's to 6.5's most likely take the vote. If its elk out to 600+ its probably the 7mm Rem mag, 7STW or 300 win mag or 300 RUM.
These are the most popular, not in a particular order. Other calibers may be more ussfull for the purpose, but these are popular for a reason.
Long range shooting is a process that ends with a result. Once you start to focus on the result (how bad your last shot was, how big the group is going to be, what your buck will score, what your match score is, what place you are in...) then you loose the capacity to focus on the process.