in that case, you will do just fine choosing any of the major manufacturers --no need to spend the extra cash on the higher end guns. i would just recommend a 16" barrel (more manuverable indoors than a 20" or 18"), a 1:9 twist rate (greater flexibility in ammo choice for what you want), "a-3"/flat top style (provides more optic options; and yes, your purchase of an a-3 will include the removable carry handle), flash suppressor (rather than compensator). as far as quad rails go, you should go with a two piece type rather than the one piece "free floating handguard" type (they are easier to install, are less expensive and, given your needs, you won't benefit from the accuracy increase anyways). in addition, if you are going to be using defensive type soft point ammo (e.g., federal's tactical load) you would be wise to choose a manufacturer that is using the "m-4 cut" on their feedramps (the standard angle on the feedramps tends to cause "bullet set-back" malfunctions with soft point bullets).