Barn boss Jim Pherson said: "We've played better this year, but at least we got the result – and I think we deserved it. We were comfortable in the end."
Joint Rathfern manager Ryan McCartney, on his 35th birthday, wasn't quite so happy, pointing to "crucial refereeing decisions that went against us". "The third goal was a real killer, and after that the heads just dropped –but I was happy enough with the performance, and early on, I thought there was no way we were going to lose."
It was Rathfern who got off on the right footing on 20 minutes when David Moore and Glyn McCartney combined to engineer an opening for Gary Weir to blast the ball past the helpless Chris Campbell.
Rangers could have been celebrating again just minutes later but a slightly hesitant Moore lost out to a more committed Campbell.
Instead, it was Barn who were back on terms, with Sharples profiting from some uncertainty at the back, nipping in to round keeper Neil Lovell.
Rathfern could have bounced right back when left back Neil Crawford ran from deep but with just the keeper in front of him, the referee whistled for offside.
However, just before half-time, the referee spotted defender Gary Lovell nudging Sharples in the back as he headed the ball clear. Rathfern were anything but happy, though Sharples showed no sympathy, tucking home the resultant penalty.
Barn extended that lead ten minutes into the second half, from a free kick that Rathfern felt ought to have gone the other way. Even so, it wasn't the cleanest strike Gary McKee will deliver this season; keeper Lovell no doubt believing the shot was creeping wide, only for it to thud off the post, with Christopher Monteith was the first to react. Rangers, having pushed out, maintained that the United defender was in an offside position.
That effectively killed off the Rathfern challenge, although the visitors' mood hardly improved when they had a penalty appeal of their own turned down, claiming that Paul Mathers had used his hand whilst clearing the ball under pressure from Colin Andrews.
There was no dispute whatsoever though about Barn's second penalty, with Gary Lovell clearly chopping down Tony Kane. Up stepped Sharples to gleefully complete his hat trick, with his 17th goal of the season.
Next Saturday, it's the Clarence Cup where Barn entertain 2B side Kircubbin, while Rathfern return to the Diamond for the visit of 1B outfit 1st Bangor Old Boys.
Barn United; Campbell – Baird, Wakeham, P Mathers, Monteith – Kelly, McKee, McKinty (Patterson), Matthews (Brown) – Sharples, Kane.
Rathfern Rangers; N Lovell – Dodds, G Lovell, Solomon (Montgomery), Crawford (Craig) – Moore, Gardiner, Sloan, Weir (J Doyle) – Andrews, G McCartney.
Referee, Mr Colin Rainey, Randalstown.
Man of the Match: Nicky Sharples