copper tubing from pump to waste pipe is held in place by silicone, which loosens, what better can i do to make this more secure?

I am going to silicone caulk around the shower edges. Is there a good way to cut the tip off the tube of caulk so the caulk goes on smoother.

We are half way through a tube of silicone caulking rubber that is being forced out the nozzle by a squeeze handle gun. It has a rod and pusher pad to make the caulk flow out the nozzle. The job is finished and we cannot pull the rod and pusher pad out of the tube. Besides cutting into the tube wall, what else can be done to pull out the rod?