I have
found this to be the most accurate system
for finding your true draw length with a
long bow when anchoring to the corner of
your mouth.
Take a
tape measure or yard stick, and place the
butt end of the tape against your sternum.
Reach straight forward with both hands and
sandwich the yard stick between your hands.
Now relax your shoulders, and check the
measurement indicated just at the tip of
your middle finger.
The
measurement may be shorter than you expect
but this will indicate your true draw length
with a longbow.
If you
have broad shoulders you may actually have a
longer draw length than indicated.