I had both balls.
The No Mercy has monster backends in its reaction. It was a very fun ball to throw, though could be a bit squirty in heavy oil. I loved the strong reaction off the breakpoint this ball had.
The Black Widow I put on the used ball rack after about 12 to 20 games. Nothing ball for me, left tons of 10 pins in multiple houses. Hit like a wet noodle. Really didn't do much of anything in any condition I used it on. It was an arc-er at best and not a very strong one for me. Both balls drilled strong, except the No Mercy had the heart in the track as the instructions suggested.
Though there's no arguing with sucess. The Black Widow is one of the most used balls by the widest variety of people. Most seem to love it. But I wouldn't call it snappy by any means. While the No Mercy (black one) was very snappy off the break point. Like I said, it was a fun ball to throw.
I used the No Mercy for many many games. It got oil soaked and I have not had a lot of time to soak it and try to bring it back.
Erin
