Why are there different opinions regarding opening bottles on Shabbat?

why are there different opinions regarding opening bottles on chabas well there are two potential problems and that leads to three huic positions the first potential problem is Mak depes which means completing this is because the cap is a seal until you unscrew it for the first time at which point you make it a usable utensil the second issue is mate cutting something to size along prescored guidelines some posts can prohibit opening any bottle whose cap leaves a ring around the bottle neck because they believe that doing so violates one of these two malas other post can permit opening all bottle caps apping that neither Mala is being violated still other post gim permit opening plastic bottle caps but not metal bottle caps and this is because of a difference in their manufacturer that results in plastic bottle caps being useful before opening but not metal caps please note that Technologies do change so this distinction may be in a constant state of flux for practical guidance in this matter be sure to ask your own rabbi