Retired brigadier general of the regiment and former national security minister Carl Alfonso has described the loss of a Galil assault rifle as "slackness" on the part of the soldier to whom the weapon was assigned.
Such an incident would warrant severe disciplinary action, he warned.
On Sunday it was reported that the soldier, who was on duty at Teteron Barracks, Chaguaramas, had lost the weapon earlier that morning.
Despite several searches of the base and its surroundings the rifle has not yet been found.
Western Division police visited the barracks on Monday, interviewed several soldiers and are continuing investigations.
Speaking with Newsday on Wednesday, Alfonso, who also served as chief of defence staff from 1994-1999, said he would not criticise the leadership of the regiment for the incident, but nevertheless, it was a blemish on their reputation and he hoped the weapon was found soon.
He said usually mechanisms and safeguards were usually in place to minimise the loss of weapons and ammunition from military bases, and the circumstances described in reports of the disappearance were unusual.
"From what I have been reading in the newspaper, this slacker signed for his weapon, which is what you have to do, and the arms storeman is the one who signs it out.
"You keep that weapon on you until your duty is finished.
"But during that 24-hour period, regular checks are made to those arms stores where the weapons are kept. The officer – who is usually a warrant officer or lieutenant – he will inspect the weapons in the arms stores once by day and once by night.
"In addition to that, there will be a battalion orderly sergeant who will assist by checking."
Alfonso said while it was not the first time a weapon had been lost at a barracks in TT, they had usually been found within a relatively short period.
"It has happened before, where the weapon was retrieved within 24 hours. I am surprised it has been for so long.
"But we normally retrieve it by any means necessary...of course the person who caused it to be missing will be severely disciplined, and possibly discharged."
Western Division police said the investigation was at a "sensitive stage" and they could not share much information, but one officer said they were taking the investigation seriously.
As of Wednesday afternoon no one had been held for the missing gun.
A cash reward of $75,000 has been offered for any information leading to the seizure of the gun.