I was always too afraid to try and frag mine. Until it got too big for my tank and I had no choice. One corner started receding from lack of light/flow.
I took it out and cut a few pieces off with a right angle grinder with a diamond blade on my garage floor. I did not dip it, I just rinsed it off in a bucket of tank water and put it back in the tank. Every piece healed up just fine (even the receding part).
A fast clean cut is way better than "bone crushers" imo. Just try to be quick.
Once it opens back up, try to feed it a little to help it heal.
Good luck