Braunton were on the receiving end of an eight-wicket thrashing by new C East leaders Heathcoat.
Sidmouth II were the long-time leaders in the division, but surrendered pole position after losing a thriller at Exmouth.
Braunton got to 114 for two thanks to runs from Ben Whitty (49), Alfie Huxtable (23) and Jack Whittaker (44), then collapsed to 183 all out as Joe Hancock (5-35) and Dylan Penberthy (2-29) got busy.
Jake Stoneman flogged an unbeaten 106 and Toby Lochead made 56 as Heathcoat raced to victory with nearly 20 overs to spare. Both wickets to fall were taken by Steve Moore (2-36).
Barnstaple and Pilton drifted further away at the foot of the C Division East table after losing by 21 runs at Whimple.
With only two wins in 10 starts so far, Barnstaple are 34 points away from safety after their latest setback.
They have not reached the point of no return yet, but in a division with three relegation places their prospects don't look good.
Cameron Kidd showed why he was named Devon League young player of the year in 2018 by rifling 110 off just 62 balls in Whimple's all-out total of 204.
Lee Cole and James Lake shared the bowling plaudits for Barnstaple with three wickets each.
Whimple skipper Ben Silk feared his side did not have enough runs on the board - and when Barnstaple got to 120 for five he may have had a point. Matt Clarke (45) and Cole (30) were the leading run getters.
Barnstaple and Pilton were 159 for seven when Clarke was dismissed, and when Lake went for 33 soon after the end wasn't far away. Four wickets went for 14 runs scored as B&P were dismissed for 173.
Pick of the Whimple bowlers were Gareth Stoneman (3-29) and Matt Richards (3-27).