Bad idea. Colt rifles are known to have an extreme allergy to vise grips....
No advice is better than bad advice. We have removed hundreds and hundreds of side mount sling swivels. It is never easy. The only sure way to get them removed/installed without damaging your rifle is with the right tools. There are tools that solve problems and tools that create problems. Vise Grips fall into the later category.
If you have the proper tools, it may be quicker and easier to remove your muzzle device and slide the sling mount off while removing your front sight base.
-Mark