Wow... There are literally hundreds of varieties of rifles out there for 500-600 bucks. Check out the link below...

http://hunting.about.com/od/toppicks...olt_rifles.htm

You also should take into consideration the caliber you want as well. .308, .270, .30-06, .243, 7mm-08, etc...etc... Anything .308 and above will drop any game animal in the US. The .243 is an excellent caliber as well, but it might be a tad on the small end for elk, moose, bear, etc...

Also, you should take into consideration the recoil (kick) of the rifle. Some rifles will kick like a mule, others won't be so bad.

Short example of rifle recoil
Caliber..........recoil energy...................recoil velocity
................."how hard it kicks".............."snappiness of kick"
.243....................8.8....................... ............8.7
.30-30.................10.6........................... .......9.5
7mm-08...............12.6............................. ....10.1
.308....................15.8...................... ...........11.7
.270....................17.1...................... ...........11.7
.30-06.................20.1........................... ......12.7

Now according to the website link below, the numbers indicate foot pounds of energy and feet per second/velocity. Chuck Hawks goes on to say that "While recoil energy determines how hard the blow to the shoulder feels, recoil velocity determines how abrupt the blow to the shoulder feels. My subjective impression is that, with a well designed stock, recoil velocity above about 10 fps begins to feel like a sharp rap on the shoulder rather than an abrupt push."

Most importantly he also says, "I estimate that fifteen foot pounds of free recoil energy and 10 fps of recoil velocity represent the approximate upper limit of the comfort level. Above that recoil becomes increasingly intrusive. Also, the effects of recoil are cumulative. The longer you shoot, and the harder the rifle kicks, the more likely you are to flinch. These are good things to remember when comparing rifle cartridges, and at the range."

http://www.chuckhawks.com/recoil_table.htm

I hope this helps you with your decision! Just imagine if you wanted a "dangerous game" rifle and you were on a trip to Africa or something. Imagine shooting the massive .458 Win Mag with a 500gr bullet at a Cape Buffalo or Rhino or something and it is listed as Recoil Energy(Kick): 62.3 with a Recoil Velocity(Snappy): 21.1 !!!!