When the dog is sent on a bite and the latches on the offender with tight jaws sometimes the dog doesn’t get a very effective bite.
For example the bite might land on the offenders jacket sleeve causing the offender initial shock but no pain or control of the offenders arm. This is really a bad situation for your dog to be in. Under no real pressure from the dog an offender can easily reach into his pocket with his other hand and produce a weapon. The dog will be none the wiser and a vicious attack on your dog will be imminent. This is where your decision to give the ‘OUT’ command is crucial. On your observation that the dog has not achieved a full bite that has the offender screaming and buckling you need to call your dog off - momentarily, if need be and give the bite command again. Training your dog to achieve a full bite is a skill that many amateur dog trainers do not understand. Just because your dog is trained to bite it may not be trained to bite well and you need to understand the ramifications that an improper bite will have and what you need to do at that point.
In summary – Do not expect that your dog will have a full bite on his first try. If trained to re-bite then you’re in luck but if no re-bite has occurred call you dog off and give the bite command again and hope he’s luckier the second time round.