On Target is a good range and good people; I'm there enough I bought a membership.
The Firing Line in Huntington Beach is the same a couple week ago as it was when I was a member there 10 years ago - continuity is nice
Orange County Indoor Range in Brea is the former Brea Range and before that was a Firing Line.
Both the Firing Line ranges are 50 feet; On Target is 75 (25 yards) which is a benefit: no limitations on ammo (magnum okay) and you can even shoot shotguns there, and frangible ammo in rifles (though why one would want to shoot a centerfire rifle at 25 yards is puzzling ...
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But the deciding factor for me is convenience: I'm in Tustin and On Target is more convenient than the other two. When I was in West Anaheim and Stanton, and worked in Huntington Beach and Costa Mesa, The Firing Line was closer. If you're north of Anaheim, OC Indoor would be closest.
I'll ditto the dislike of Evan's due to cost and attitude.
Insight Range in Artesia is convenient for 'way west OC (Los Alamitos/Cypress/Seal Beach) and a great place.
The Sheriff's range in Orange across the street from the Pond arena is open to the public but has odd restrictions.
There are no outdoor ranges left in OC. I go to Prado and Mike Raahauge's for matches, am a member at West End Gun Club near Fontana, and get up to Burro Canyon for occasional shoots.
Oh, and Iron Sights in Oceanside is not too far if you're in 'way south Orange County, though On Target is closer; they are actually very similar.
Oh yeah, On Target is a gun store as well, and if you buy one there you can shoot it at the range during the waiting period. Excellent pricing, fair selection.