I used to dive with some guys that carried really big guns with a lot of bands, including one they called the Grouper Band. I wasn't able to set that one, so I just used 2. Then, one day, I watched a commercial spero go to work on half a dozen groupers using a medium size gun with only one band, & it wasn't any kind of massive "Grouper Band" like the other guys were using. He set that band over & over again easily. I still carry 2 bands on my gun, but the second is only there in case the first one breaks. I no longer use super stiff bands. I no longer get chest bruises. It may be best for you to start with a different question, like - how strong of a band do I really need?