I've had luck doing it a little differently. First determine where the end of the barrel is by iserting a dowel or whatever you have in the muzzle end until you hit the end of the barrel and use this as a guide to measure where to cut the muzzle brake off (leave an eight of an inch or so to avoid damaging the barrel.) Cut the brake off with a hacksaw or cutoff wheel. Then I use a dremel cutoff wheel to make two cuts lengthwise (parallel to the barrel), nearly through the thickness of the brake. Then I insert a strong screwdriver or pry bar into one of the cuts I just made and pry it apart. The remaining piece of the brake should pop off. The only tricky part is determining how deep to make your lengthwise cuts with the dremel tool. Even if you go a little deep and nick the barrel threads, the new flashider or brake covers it when it screws on.