Spot welds with a MIG

[nogera@juno.com]

Anyone got any suggestions for making spot type welds with a  MIG 
welder? 
I've tried drilling a 1/8  inch hole and welding up the hole but I always
end up  filling the hole but I get no  penetration to the solid sheet
under the hole.

It's 20 gauge cold roll. 

The weld is joining  two 1/4 inch flanges so I really can't  make the
holes bigger.
Would welding the ends of the two flanges be as strong as spot welds ?

Thanks for any advise.

Bob