The Rushmills side attacked virtually non-stop in the first-half but failed to get any points on the board.
They were made to pay as on a rare Mens Own break, the Ashton side kicked a penalty through Mark Newton to make it 3-0 at half-time.
The
second half started well for Casuals as they scored a try through Andy Goslett to go 5-3 ahead, but that was to be as good as it got.
With 20 minutes remaining, Neil Owen powered over from close range to put Own 8-5 ahead, but in the process of that move Ryan Duffy was left prone on the ground with a broken ankle.
Not wanting to move the injured player, the teams had to move to another pitch to take the conversion and to be able to complete the game.
Newton could not convert the try, but Own seem spurred on to greater things.
This led to Newton kicking two penalties, one from 45 metres, to take the score to 14-5.
Things soon got even better for Own as winger Alex Cairns crossed for his first try for the club to make it 19-5 and push Own up to third place in the league.
Next week will be interesting when runaway league leaders Market Harborough visit Ashton (ko 2.15pm).
Everybody at Casuals, who this Saturday travel for another derby against Bugbrooke, would like to wish the unfortunate Duffy a speedy recovery from his injury.