I just ran some gcode to drill a deep hole using peck drilling, but instead it just plunged straight to the bottom of the hole (no pecking). It simulates fine in my CAM software. Here is the script I used:

Code:
(1001)
(T1  D=4. CR=0. TAPER=118DEG - ZMIN=-18. - DRILL)
G90 G94 G91.1 G40 G49 G17
G21


(DRILL2)
M5
M9
T1 M6
S4850 M3
G54
G0 A0.
M900
G0 X0. Y0.
G43 Z20. H1
Z15.
G98 G83 X0. Y0. Z-18. R5. Q2. F485.
G80
Z20.


M901
M30