JIM,
I agree that EN TW...EKTEINEIN is instrumental - 'by stretching out your
arm' - in Acts 4.30. Another instance in Acts is in 3.26 - EN TW
APOSTREFEIN - 'by turning'.
I would suggest the following are also instrumental:
Luke 12.15 EN TW PERISSEUEIN - 'by having in abundance'
Romans 15.13 EN TW PISTEUEIN - 'by believing'
Hebrews 3.12 EN TW APOSTHNAI - 'by deserting'
Hebrews 8.13 EN TW LEGEIN - 'by speaking'
In his commentary, THE ACTS OF THE APOSTLES (London, 1951), F.F.Bruce
categorizes both 3.26 and 4.30 as 'instrumental' (page 129).
Brian E. Wilson