Guy,
The benchrest rifle club near wentzville is a very worthy range; it has up to 600 yards to play with. there is a membership fee, but the unvested one is quite reasonable - about $150 the last time I checked. reifsneider has also been visited, yes, it is free. go to the missouri dept. of conservation page on the 'net & you will find a list of ranges. there are several free ones; busch wildlife is a pay-per-visit & is highly regulated; pretty nice, though.
enjoy.