In a social media post before he left for Denver, Beament said the 754.3 metres (2,849 feet) achieved in one month with a single jumbo development team was "unbelievable".

The Byrnecut development crew broke the record solo-jumbo monthly development mark set way back in 2013 at Dugald River in Queensland.

Beament said in his Denver Gold Forum presentation the lateral development record beat the previous best at Jundee of 640m in September, 2018, another Byrnecut benchmark.

The Australian-based international mining contractor has been working at Jundee since 2001.

Beament said the record-breaking team bolted and meshed all 754.3m of development. There were no safety-related incidents.

"The key to success was preparation, planning, scheduling, optimisation, management and letting the team execute," he said.

"There was an unbelievable level of Northern Star and Byrnecut collaboration [needed] to achieve this."

Jundee, about 45km northeast of Wiluna in Western Australia, started producing from openpits in 1995 and now produces 260,000-280,000oz a year from circa-1.8 million tonnes per annum of underground production (three mines) at all-in sustaining costs of US$780-836/oz.

Byrnecut Australia managing director Pat Boniwell said the development performance in the Invicta underground was outstanding - a mark the veteran underground miner didn't expect to see.

"I must admit I didn't expect to see a single-jumbo crew, with a full bolt and mesh ground support regime, get that kind of development," he said.

"I got a text from the mining GM at one of the leading mines in the country saying, awesome metres, we'd like to know how you did it and what advice you can give us.

"There are operations around that 700m mark that would like to do it with one jumbo not two, or even three or more. Seventy percent of the [Jundee Invicta] development was 4.5m-by-4.5m, the remainder 5.8m-by-6m, so an average of 5m-by-5m development for the month, all with split-sets and mesh, every heading.

"It's pretty rare that you get an opportunity with the right operation, the right number of available work areas, the right group of talent, and motivated people together, and a client that very much wants that rate of development as well - and [Northern Star] is aggressive and very proactive. There's an element of all the planets aligning, but fundamentally you just need a well organised talented crew of people to pull that off. And it's not just 3-4 operators, it's a lot more than that.

"You have to have everything working together seamlessly from your initial planning design, through to all the technical support that goes on behind the scenes - issuing of plans, geological support, survey support - then you need crews that can execute, including the back-up to that frontline jumbo crew; your service crew, your charge-up guys, your boggers, the maintenance that sits behind it to get that machine availability there for the entire month.

"The drill crew do need to be good - and they're obviously very good.

"The development-intensive nature of Jundee does lend itself to elevated development rates because the collective team are experienced and have an expectation of high development rates. They're very well versed in what they need to get that in terms of things like power reticulation, ventilation - the service infrastructure behind the development - through to rotation of the loaders and trucks to clean the material out of the headings, to having the headings set up right for the jumbo operators. It takes time to refine those processes, and in this instance everything went perfectly right for the entire month.

"The most impressive thing for me is that was all done with zero incidents across the whole site, for the whole month. The site got just under 1,800m [total development metres] for the month, which is impressive in itself."

The twin-boom Sandvik 421 jumbo in use at Invicta that achieved more than 75,800 drill-metres for the month also came close to breaking a longstanding record of 76,000m set at a WA copper mine.

Boniwell said single-jumbo development at these sorts of elevated rates - while uncommon - was clearly advantageous from a capital and operating efficiency standpoint, as well as safety, with fewer personnel working at the face.

While using only one machine to drill and install ground support in a development heading is a typically Australian hard-rock mining practice, Byrnecut has exported the approach to Africa and other parts of the world.

Northern Star is confident it can adopt leading-edge mine development and production practices at the recently acquired Pogo gold mine in Alaska, USA.

And other Australia-based gold and base metal miners, such as Newcrest Mining, St Barbara, OceanaGold and South32, will be striving for world's best practice at sites in the US and Canada.

Jundee's record gives them all something to shoot for.