Need more information. Exactly what are you trying to weld. Most mig guns have a choice of smaller diameter nozzles.
If I have a tight corner and very little room to get in there I have a gas cup that I've cut back until about an 1/8" of the electrode tip sticks out. Then I just unscrew the regular cup, screw the short one on and start welding. It allows me to get a little deeper with the Weld and allows me to see the tip better when it's stuck up into a corner.... .