Mass Effect

[Space Suicide]

Maybe I just haven't figured out how to change weapons in battle, who knows.

It's just like the other games, click LB to bring up the Weapons Wheel. RB is the Power Wheel. Doing that will toggle what weapon or biotic power you want.

I think I know what you're talking about...

If you have the rifle you don't like equipped and want to equip another rifle then the only way to do that is at a weapons terminal or in the Armory on the Normandy. You can't switch rifles in the middle of a mission by click start and going to equipment like the first game allows.