A 10 power scope is good to 500 yards just make sure that it has good glass. My choice for a 10 power scope to shoot 500 yards would be (from good to best):
You can pick up a Mark 4 3.5-10X40 ill for about $1,150 on Amazon.com though you might find one for around $1,000 elswere. All of these other scopes start at that price point and go up rapidly from there.
I've got one on my Sr25 (TMR) reticle and have not any problems with it...I have Leupold Mk4 8.5-25x50mm with an illuminated mildot that works very well for me as well...probably going to be upgrading that one in the near future though
I am a big fan of the TMR reticle and have one on my 18"AR for local critter hunting. I just picked up an IOR in 4-14X50 and absolutely love the glass. It is hard to find one in a store to look at but I recommend checking it out. You can never go wrong with a Nightforce if you want to do some upgrading.