Darren Weir's season of milestones has continued with the Melbourne Cup-winning trainer setting a Commonwealth record for winners in a season.

Weir brought up win No.335 for the 2015/16 season when sprinter Gun Case won a 1000m race at Moonee Valley on Wednesday.

Trainer John Hawkes held the previous mark of 334 set in 2002/03.

Weir had several chances at Wednesday's meeting to bring up the milestone but it took until the sixth race for Gun Case to register the win he needed.

Last Saturday Weir became just the fourth trainer to reach 100 metropolitan winners in Victoria in a season, something previously achieved by Lee Freedman, David Hayes and Peter Moody.

Weir was relieved to get the milestone out of the way on Wednesday after arriving at Moonee Valley mid-meeting.

"Hopefully people will stop mentioning it now," Weir said.

"I was getting a bit sick of that, but it's a nice way to do it."

Weir went within two of reaching 300 wins for the first time last season and he still has the rest of this month to improve on this season's tally.

The highlight has been his first Melbourne Cup win with outsider Prince Of Penzance last November at Flemington.

He believes he will be hard-pressed to improve on this season.

"It would be hard to toss, I would have thought," Weir said.

"The Melbourne Cup is obviously the highlight and then the six Group Ones and the 100 metro winners in Melbourne. And this just tops it off, I guess.

"You don't get time to think about it, to be honest. You just go to the races, get home and get organised for the next day, go to bed, get up and then do it all again.

"It's just routine but I really enjoy the horse training side of it, and I've mentioned before that I'm not that keen on any other side of it but I've got great people that do that. So big thanks to all of them."

Gun Case sprinted to a 3-1/2 length win in the benchmark race under apprentice Ben Allen.

And while it was a significant achievement for Weir, for Allen it was his first Moonee Valley winner.

Allen also brought up his first city winner earlier this season at Sandown on a horse trained by Weir.