I ahve two MT6400C Carbines and recently replaced the original post-ban lookalike noncollapsible stock with a Colt 4 position pre=ban and a Vltor. Using a $E25 AR armorer's wrench, which is heavy duty, I had no problem removing either stock and replacing them with the collapsibles . No torches, dremels or tricks, just the right tool and no problems. I wouldn't recommend trying it with a cheapo CAR stock wrench or worse yet, regular hand tools. The $25 investment is well worth it and can be used for a lot of AR chores.