A professional shooter's .223 calibre bullet from 60 metres away removed most of the head of the eastern grey, one of three females grazing on Mulligans Flat Nature Reserve about 6.15pm.

Raised on a farm, the shooter says the birth of an animal can be as gory as what lies at his feet.

''Certainly the average Canberran would see this on the road every day and far worse than this, there would be a broken leg or a …''

His voice trails off before he's asked more questions. ACT Parks and Conservation has allowed two journalists to record test firing and the immediate aftermath of a direct kill, but not the actual cull, in its final stages in Canberra.

The cull and media access to it are as tightly controlled as the neighbourhood homes compressed against the reserve's edge. Video and still images from a previous night are given to us on a disc and we are taken away after one hit, with instructions not to identify the two shooters or their vehicle.

The bullet exploded on impact to kill instantly and to end the projectile's dangerous journey.

A senior veterinary officer with ACT Parks, who checks the shooters are within a national code of practice, looks at the 50-kilogram fallen roo.

''No dragging of this carcass. There is the massive blood loss associated with the head shot. Spot-on head shot, middle of the brain. Bits of various brains around there. It has virtually dropped where it is.''

Anything less is unacceptable. The risk of injuring kangaroos or people is more stressful than killing, says the shooter, who works with another one as they drive, spotlight and fire. Twice during the current cull they have needed to fire a second shot to the chest two seconds after the first shot, which was slightly off target.

The first time, the kangaroo moved. The second time, the bullet hit a branch.

When the roos are in a mob, the shooters can reload with a bolt action and shoot every three seconds, targeting whichever roo is calmest and safest to be shot. They don't shoot moving kangaroos.

''If there's four there, we'll usually get the four,'' said the contractor, who once represented Australia at target shooting.

When they find a joey inside a female they follow the code of practice.

''You just remove the pouch young and it's a blunt strike to the rear of the head. They are a very fragile animal, and basically it kills them instantly.''

Entry into Mulligans Flat on dusk was diverted when a man reading a book in a car near the main gate caused a quick change of plans.

Six vehicles with two rangers

co-ordinated security for the cull. No one could say whether the man reading his book was a ''suspect'' or ''definite'' protester, nor did they ask. Instead vehicles headed to the back of the reserve near the NSW border.

The shooters say they are under no pressure to achieve 1244 kills, this year's revised quota. They shoot up to 100 a night, and will stop at any stage if they believe it's unsafe. They

are confident in the team, yet say they feel a little frustration when a tribunal rules in favour of a cull, but protests continue.

''Just stress that our whole business is on the line and our personal reputations; there's an element of danger if these extremists get hold of our identities,'' says the shooter.

''This project is obviously exceptionally high stress on us. As in there is very [limited] acceptance of injury, if any at all; on this program we have not injured an animal at all.

''I don't know whether that's been achieved in a feral animal program before. There's never been scrutiny at this type of level to really see how successful other programs are.''

In yellow and orange safety jackets and overalls, they fire at least six rounds before the cull, checking a matchbox-sized target taped to a white plastic drum.

Their four-wheel-drive's windscreen is pushed out to makes room for Remington and Howa rifles, which rest on a small sandbag on top of the dashboard. The marksmen have two means of vision - thermal and night vision.

''Thermal gives you any body heat out there, so it's a real safety margin thing,'' the shooter said.

Additionally, an infrared elimination spotlight makes sure both men are on the same target, a big help when it comes to finding and retrieving what has been shot.

Travelling throughout Australia shooting all types of feral animals, their night vision reveals an amazing stage of unguarded nocturnal animals.

''Watching sheep being hit by wild dogs or foxes, you actually see them do it. They don't know you are there; you see the true hunting behaviour and what's happening out there,'' the full-time professional said.

On their sixth cull in Canberra, they say they know the country well.

Their firearms are accurate to 300 metres, but they shoot within a maximum of 110 metres and as close as 40 metres to minimise variances from wind and the terrain.

Kangaroos go to the gullies in high winds, and shelter under trees when the temperature drops below zero. Monday night's heavy cloud cover, low visibility and little wind were ideal.

Any thrill of the hunt has long gone. They shoot until the early hours of the morning and say the hardest part is maintaining high accuracy.