Hull-based Martin Williams Ltd took over Penman Engineering near Dumfries in November last year.
The number of employees at the time had fallen to just 14 but the new owners said that now stood at 67.
Director Chris Williams said that if new work they hoped to secure did come in then numbers would rise further.
He said that would also leave them with the potential of a full order book for the next two years.
The site on the outskirts of Dumfries employed about 140 staff before it went into administration.
Mr Williams said they had completed their first stage of restructuring the company while managing to increase staffing levels.
He said they had concentrated on re-employing as many people as possible while building up orders.
"We have had massive support from Scottish Enterprise who have helped us from the day we took over and hold regular meetings with us to offer their support in a lot of different ways," he said.
"There are numerous different projects we are tendering for currently internationally and SE have also offered us support with this as well which is invaluable to us."
He said they had faced a number of challenges with suppliers who had lost money when the old company entered administration "understandably wary" of doing business with them.
"However, those who support the company will be rewarded in the future as bigger projects come off," he said.
"We will aim to put as much money back into the local economy and previous suppliers as possible to enable us to trade freely and have a good reputation in the future, the same as our existing company."
He said that overall he was positive about the direction the business was heading in.
"All in all things are looking good for the future," he said.
"It is still a tough climate and with Brexit you just don't know what's around the corner.
"But we are carrying on with what we know best which is to give the customer the best possible service and turnaround time that is also competitively priced."
Staffing levels could be set to double at a Scottish armoured vehicle business which was bought out of administration nearly six months ago.