The opening batsman hit 12 fours and a six in his 140-ball innings at The Ridge.
It was the former Portsmouth & Southsea and Hambledon player’s first league century since 127 against Alton in the last game of the 2018 SPL campaign.
His latest ton helped Burridge to a fine success after South Wilts had recovered from a poor start to post 203-6.
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Dan Stancliffe (2-46) dismissed Wilts openers Tom Morton (5) and Jack Stearman (0) cheaply, but No 3 Peter Rowe led a fightback by hitting five fours and four sixes. Rowe was four short of a century, after sharing a 124-run stand with Ben Draper (60) for the fourth wicket, when he was run out by Jack Paskins.
Will Donald (2-26) was also in the wickets with Draper - caught by Collings-Wells - among his victims.
Collings-Wells entered the game having scored just 108 runs in eight league innings in 2021. But he almost doubled that tally as his side claimed a second successive SPL victory.
Azimunnoor Chowdhury (35) helped him put on 71 for the first wicket, skipper Hilio De Abreu (23) played his role in a 72-run stand for the third wicket, and Chris Blake (13 not out) was there at the end having shared an unbroken 45-run stand for the fourth wicket.
The 40-year-old - who has played seven County Championship games for Northants this year, hit 69 as the New Forest club won by four wickets at Jubilee Fields.
After returning 0-45 when Alton posted 225-5, Berg - who played for Hampshire between 2014-19 - arrived in the middle with his new side 91-3.
He proceeded to add 102 for the fourth wicket with South African overseas all-rounder Ximus Du Plooy (50).
Berg - who has two first class centuries to his name from 140 matches - eventually fell after hitting seven fours and two sixes in a 53-ball innings.
Du Plooy fell shortly after but Lymington had more than five overs in hand when they hit the winning runs.
Earlier, current Hampshire professional Fletcha Middleton (82) had top scored for Alton after they had been put in.