Sometimes clipping a spring can cause a problem. If you look at the original end, you'll notice it is finished square to the body of the spring. You can stand the spring on end and it will balance. When you clip it this is no longer true. This can cause the spring to *** and scrape when you re-install it. If you see this, you might have to tweak the end of the spring so it sits flat. I wouldn't clip a spring unless you have a spare back-up.
Springs from old ball point pens are sometimes useful.
I like to add grip pads to my airbrushes with double sticky tape. I have some thin suede that works well. It makes them more comfortable to hold.
Don