long and the short..
options.
stationary light..
not too strong and long lasting on the batteries, leave one up over food for a week or so untill they think thats the narm.. hey presto no torch on the gun needed.(can even put markers up for distance)
light on the gun..
they'll get used to any light faster if you go more regularly, every night and a wekk is good going.(you'll think there isnt any left after 2 weeks...).
start of white, then switch to coloured filters, red about the best, orange works etc, blues a strange one but funny if its a pulses LED torch lool, they cant walk