I am just wondering... are supposed to use a cockring with a penis pump? ... does that make it better or what?
No you aren't supposed to use a cockring while pumping.
A cockring works by stopping some of the blood from flowing back out of the erection, and if you pump while wearing one you will significantly increase the chances of bursting blood vessels.
The danger is that you may not feel this happen.
I recommend that you take breaks every 20 mins (or less) and massage the penis (and scrotum) with a moisturiser (containing Vitamin E) for at least 5 mins between pumping sessions. Examine the skin and look out for blemishes or dark colouration, which if found is probably small blood vessel bursts and I highly recommend that you do not continue pumping (or use a cockring) for at least several days..... and if the patches of discolouration change or grow perhaps you should seek medical advice.
The manufacturers of these devices won't warn you of the dangers, disclaiming their responsiblity by claiming that it is a toy or some such other thing...
You are very sensible to ask about the dangers.
Joe
ps If you need to know any more, send me a Personal Message and I will ask an experienced pumper (who happens to be a 'Friend'.) for his advice.