"The dogs went and tried to contain it in thick bush and then we were able to get our hands on it and stick it multiple times," he said.
The experienced hunter said it was more than double the weight of the largest boar he had previously caught.
"It's by far the biggest one I've ever caught. The largest one I'd caught before this was 170 pounds but this weighed 344 pounds.
"It's the hunt of a lifetime, a monster of a pig."
Mr Coulson said he did not want to divulge where the hunt took place "as it might give away our spots," but he said it had been a very long time since a boar that big had been caught in the locality.
"It's a trophy pig."
All four dogs were injured during the hunt but after a few days at the vet and some stitches they were recovering.
Mr Coulson said he had a great love for hunting which had been reignited after a few years living in an urban environment.
"We're still buzzing, when you're doing it for years it means a lot. I had a break and moved to the city for a few years but hunting is in our blood."
He said a few families would be well fed following the prized capture.
"We brought it into the butchers in Carterton and he made lots of salami, sausages and bacon out of it.
"We each have plenty for all our friends and families. The dogs will get a few sausages too."