He and Bharat Popli put on 84 before Popli went for 16 but MacRury continued on to 75 before he was out in the 20th over with the Bay on track at 105-3. Joe Carter stepped up as the major player in key partnerships but wickets kept falling as the target got closer.
With 28 needed off six overs Pringle joined Carter with just three wickets left. A needless run-out left the Bay perilously placed. Carter and Tommy Clout added 14 off two overs before the match-turning dismissal of Carter for 45 at 199-9.
The last pair of Clout and Chris Atkinson did their best to get the nine needed off the final over but after leading on the first innings Counties Manukau were not to be denied.
Earlier on Saturday Counties Manukau won the toss and batted first. Led by 54 off 248 balls by opener Sam Varcoe, Counties batted 122.3 overs in making 235 at a tedious run rate of 1.9 per over. It seemed nowhere near enough against the powerful Bay batting line-up but was plenty in the end.
Seamer Atkinson and Tauranga Boys' College Year 11 spinner Tim Pringle took three wickets each. Pringle became the youngest player on Hawke Cup debut for Bay of Plenty at 15 years and 169 days.
Bay of Plenty lost openers Peter Drysdale and Tom MacRury in the first 13 balls of the run chase. Carter and Ben Musgrave eased into a partnership of 76 before Musgrave was out for 31.
Carter fell for a well-made 42 with six boundaries at 85-5 and, apart from a typical fighting knock of 41 from keeper Tim Clarke, the innings was a major disappointment.
Counties Manukau led by 99 at stumps on day two but former NZ Under-19 pace bowler Sean Davey got stuck into the top order early yesterday taking 5-34.
The last wicket pair of Reid Somani and Scott Johnston crucially used up 12 valuable overs before Counties Manukau were bundled out for 142 leaving the Bay 212 off 41 overs at 5.17 per over to retain the Hawke Cup.
In the end, it was just too much to chase down.
The hero for Counties Manukau was left-arm spinner Ben Reece who took 6-36 in an unchanged 13-over spell.
Counties Manukau 235 (SS Varcoe 54; CM Atkinson 3-32, TJ Pringle 3-67) and 142 (SB Davey 5-34, TJ Pringle 2-22) defeated Bay of Plenty 166 (JF Carter 42, TJ Clarke 41, BS Musgrave 31) and 209 (TJ MacRury 75, JF Carter 45; BJ Reece 6-36.)