As Bond1 has said.
In fact any large scale model can cause collision probs in many engines as has again been discussed at these and many other forums.
Scale and using it excessively can affect and be affected by many things - remember that a large object will automatically have physics attributes applied to it the by FPSC when first imported or placed in a level and this also can have an impact on behaviours. You may need play around with these auto Physics settings in some instances.
There are many issues affected by scaling that could impact though most of them will have been discused previously and a user will by discovery find their own solutions to issues if its at all possible.
In the case of Characters of course the Collision box itself may be impared by large size scaling of a Character. The Character itself may physically change in size but I am not sure how the engine then handles the collision boundary for that situaton - it may not be able to accommodate a variable adjustment significant enough to allow for credible collision detection?
Because of this engine registering of collision for hits from weapons may also be affected.
As most things in FPSC are relative and tied in to the single tile concept and scale then - objects of vastly larger or smaller proportions may well cause all kinds of problems. Some will some wont.
If you cant shoot a tall street lamp to death for instance it wont matter much - but an enemy is another matter.
Trial and error is your best friend.
"I am and forever will be your friend"
