I recently purchased a Kral puncher and now i am slowly searching for a dive cylinder for it. This is my first pneumatic and I have read up a bit but being a first timer the woes of buying wrong is lurking as i am seeing different dive cylinders for sale at different prices. Also cylinders that DO and DON'T have the necessary testing in date. So:
1. What do i need to know or look for when buying a cylinder where the Hydro/visual testing has expired?
2. What is the main difference with filling with a 232 and 300 bar cylinder - Is it just the higher pressure and number of fills?
Are there any other need to knows that you would suggest to a newby pneumatist?