Hi, I am not necessarily the most experienced person here, but I think I can answer questions 1 and 2.
Starting with your second question, when the bolt is pulled, the piston is pulled back and the spring is compressed. When the trigger us pulled, the spring pushes the piston forward, compressing the air in the cylinder. That air is then forced through the nozzle and into the barrel.
To answer your first question, I would imagine that the shape wouldn't matter but rather how good the air seal is. The only difference time I can think of that the shape would matter would be if you use an airbrake. But again, I'm not necessarily the most experienced person here.
Ass for your third question, I've never heard of X-Rings before, so I have no clue.
Hope that something in there helped a little anyway, sorry for the long post.
Starting with your second question, when the bolt is pulled, the piston is pulled back and the spring is compressed. When the trigger us pulled, the spring pushes the piston forward, compressing the air in the cylinder. That air is then forced through the nozzle and into the barrel.
To answer your first question, I would imagine that the shape wouldn't matter but rather how good the air seal is. The only difference time I can think of that the shape would matter would be if you use an airbrake. But again, I'm not necessarily the most experienced person here.
Ass for your third question, I've never heard of X-Rings before, so I have no clue.
Hope that something in there helped a little anyway, sorry for the long post.