I think that sums it up.
Originally Posted by bwal74
It's effectiveness at distance all depends on the lasers divergence. A good quality laser sight (US$400) has a quoted divergence of 1.2mrad which will give you a 180mm dot at 150 metres. I checked on ebay and only found one "cheap" laser sight ($80) that quoted divergence, which was <1.2mrad ... although when I look at the one you linked to it had which I think is actually meant to be a divergence of <1.2mrad. Not sure if I would trust that figure.
What size dot were you getting at 150m?
Bite off more than you can chew and then chew like crazy.