Call Wolff Gunsprings. I use Wolff 6# striker and trigger springs in all of my Glock pistols. In 10 years I've never had the slightest problem, nor any reason to change. IMO, 4# striker springs are only good for use in, 'range toys'. A 4# striker spring doesn't belong in a serious working pistol; AND, a 4# striker spring adds absolutely nothing to any Glock when it's used in, 'the right hands'.
Remember: It's not the trigger's, 'let-off' that's important; instead, it's the trigger's reset; and, here, 6# springs make a real, perceptible difference.
'Wisdom To One Is Foolishness To Another; But, Alas, A Fool Knows Not The Difference; And, The Road To Hell? ...... It Remains Well Trod By Those Who Should Know Better.'