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You are correct, no centerfire riles. You can use a .22 upper on your AR to practice.
There are also a few other rules - there are some pistol calibers that you cannot shoot - ex FN 5.7
You also cannot shoot pistol caliber carbines - ex your Kel-Tec Sub2000 or AR in 9mm etc..
You cannot shoot shotguns, except at the SD shotgun matches.
You can draw from holster, move, rapid fire, use barricades, etc.
I think the rifle rule is because of zoning and that is the only way they can keep the range open. There is a range south of Dallas that does allow everything, though its a bit farther.

Hope that helps.