A soldier who died after falling into a Waiouru lake during a training exercise should have been able to release a 20kg gun easily, the former Chief of Army says.
Defence Force safety practices have come under the spotlight after a court of inquiry report found a number of safety factors were to blame for the death of Private Michael Victor Ross.
The 29-year-old soldier was weeks away from being discharged from the army when he fell from an inflatable boat last September.
He disappeared under the water and his body was found a week later.
A leaked report to some media from a court of inquiry said an internal Defence Force investigation had found that several factors were involved in Private Ross's death, including a life jacket that failed to inflate because its gas canister had not been replaced after it was used.
Former Chief of Army Major General Lou Gardiner told Radio New Zealand defence training was "inherently dangerous".
"So therefore, there's a huge emphasis placed on safety procedures to mitigate that risk as much as possible.
"Albeit, you can't remove all dangers."
But Major General Gardiner said safety procedures should be continually updated to ensure they remained relevant.
"One of the things we do have, like everybody else, is we have human failings and people start ignoring things that should be undertaken," he said.
"Now obviously, that's a mistake."
Major General Gardiner said he was "surprised" Private Ross was unable to release his heavy machine gun.
"I would have thought, when a situation like this arose, that you could just click it and it would fall off."
He understood the life jacket had come from the navy because the army had run out of them.
"That could have been part of the problem."
If a used gas canister had not been replaced in Private Ross's lifejacket, then that would no doubt have breached safety procedures, Major General Gardiner said.
The Defence Force said in any training programme there was a safety precaution element to it, he said.
Defence Minister Jonathan Coleman told Radio New Zealand the court of inquiry was yet to be finished, so it was too early to speculate on what the final outcome and recommendations would be.
"I think there will be some very hard lessons learnt out of what is a very tragic case."
He was "disappointed" that opposition members had blamed the death on spending cuts to the military by the Government.
Dr Coleman said that during a preliminary briefing by the Defence Force, he was told Private Ross's death was "entirely preventable".
"But my first take on it, it's got nothing to do with those political points that (Labour defence spokesman) Phil Goff was trying to make.
"I think it's pretty low to link what is an absolute tragedy in that way."
Mr Goff said five non-combat related deaths in two years pointed to safety issues within the Defence Force.
"Those deaths, in most cases, have been very clearly avoidable and there have been very clear systemic errors that the Defence Force has been allowed to continue and that may be a result of Government policy and the demand for cuts in funding for some areas, it may simply be that low moral has lead to those rules not being followed," he told Radio New Zealand.
There were a number of inquiries into Private Ross's death, including by the Military Police, the Ministry of Business, Innovation and Employment, the police and the Coroner.