I have used one of those small 3 or 4 inch cheap vise grips. I have ground the serrations off of, and polished the jaws so they don;t scratch the spring and create "stress-risers". I also reworked the ends of the jaws to make them less bulky. I don't use them to compress the spring, but to hold it once the frizzen compresses it. the adjustment screw on the vise-grip lets me set the minimal amount of compression needed to get the springs in and out so I don;t accidentally over compress them.