I use a set of electronic scales that can weigh to 2000kg...... much more accurate.....a round 7 months they should be around 100 kg or a little more. It takes 6 motnhs to grow to bacon and weigh in at 115 kg.
Mind you my pigs are on self feeders for the whole of their young lives, with a change of paddocks rather than a change of feeds in the feeder. The weight of the pig is determined and the change of pen is take when the desired weight is reached.