"His actions were spontaneous on witnessing what he believed to be enemy fire," the report said.
Four other marines were injured and evacuated but confusion at the scene meant troops withdrew before they realised L/Cpl Ford was still missing.
But the report said it was likely the head wound would have killed him instantaneously.
Bullet fragments were found to be "more consistent" with a Nato round than a Taleban bullet.
L/Cpl Ford, 30, the eldest of three brothers, had been living in Dundee with fiancee Ina.
In a tribute, the Ministry of Defence said he had been thinking about leaving the service to settle down and start a family.
L/Cpl Ford's mother Joan, from Immingham, Lincolnshire, described her son as a "larger than life character who lived his life to the full".
"He was a wonderful son to me and brother to Thomas and Scott and was looking forward to his future," she said.
'Heat of battle'
The report's recommendations said training "must reflect operational reality" as well as the "most demanding scenarios".
The inability of the Viking crewmen to communicate with dismounted troops was the only equipment deficiency cited.
The Royal Navy said the recommendations of the report had all been addressed.
Maj Gen Jerry Thomas, commanding officer of 3 Commando Brigade at the time, said: "Although there was risk in mounting this offensive, the decision was made after a careful judgment, accepting that, while risk can be minimised, it can never be removed entirely."
Defence analyst Mike Dewar told the BBC mistakes were sometimes made in the heat of battle.
"However good the indoctrination and the in-theatre acclimatisation, and all the things that are done already, however good that is, we will always continue to get these sort of incidents," he said.
Armed Forces Minister Bob Ainsworth acknowledged there were "issues" about preparation, but said the mission had seen "incredible acts of heroism, courage under fire and sacrifice".
"But that does not mean that we should not learn lessons from the tragic loss of L/Cpl Mathew Ford."
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