no, the improved modified is between a full choke and a modified choke check out this website http://www.wildfowlmag.com/tips_strategies/shotgun_062304/
from smallest pattern to largest: full improved modified modified improved cylinder cylinder (no choke)
Modified is a smaller, tighter pattern than improved cylinder. Basically, the slope in a modified choke tube is steeper than an improved cylinder choke tube.
'*' designates full choke (F). '*-' designates improved modified choke (IM). '**' designates modified choke (M). '**-' designates improved cylinder choke (IC). '**$' designates skeet (SK). '***' designates cylinder bore (CYL).
'*' designates full choke (F). '*-' designates improved modified choke (IM). '**' designates modified choke (M). '**-' designates improved cylinder choke (IC). '**$' designates skeet (SK). '***' designates cylinder bore (CYL).
Full choke, improved cylinder, and modified.
'*' designates full choke (F). '*-' designates improved modified choke (IM). '**' designates modified choke (M). '**-' designates improved cylinder choke (IC). '**$' designates skeet (SK). '***' designates cylinder bore (CYL).
'*' designates full choke (F). '*-' designates improved modified choke (IM). '**' designates modified choke (M). '**-' designates improved cylinder choke (IC). '**$' designates skeet (SK). '***' designates cylinder bore (CYL).
Improved Modified.
BROWNING CHOKES AND THEIR CODES (ON REAR LEFT-SIDE OF BARREL)'*' designates full choke (F).'*-' designates improved modified choke (IM).'**' designates modified choke (M).'**-' designates improved cylinder choke (IC).
* FC (full choke) **- IC (improved cylinder *- IM (improved modified) SS SK (skeet) ** M (modified) *** CYL (cylinder)
'*' designates full choke (F). '*-' designates improved modified choke (IM). '**' designates modified choke (M). '**-' designates improved cylinder choke (IC). '**$' designates skeet (SK). '***' designates cylinder bore (CYL).
You can use steel shot with a choke anywhere from cylinder to modified, i wouldn't recommend using steel with a improved modified or a full choke.