Wow! The timing of this thread is absolutely uncanny! :tup:
I just started playing around with the team cannons
last weekend.

.
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I also had the same trouble as Skorch getting the cannons
to acknowledge my presence at first. Of course, they would shoot
back when I shot them first but, that is no fun!
.
After playing around with them for a while I discovered it is just
as
Bot 40 said. The team cannon is a pawn.
And as with any pawn it has
AI fields to adjust. Try
changing the
hearing threshold, peripheral vision, and sight radius fields. That cannon will be kicking your ass within no time.
They sure did me!

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In case you are wondering ... ...
I used the
"Dammo5" for the projectile and
"activates.Crystals.beam3bS' for the sound.
While playing around I noticed that the 5 different dispursion
ammo projectiles give different damage amounts. The orange one
in the below shot is an instagibb. With the sound I chose it
worked out pretty cool I think.
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Here is a screenshot:
http://lxixgto.tripod.com/lxixgto/ 