This is a hammer-mounted firing pin, right?
Almost ALL makers of such set them up a little bit "sloppy". Under 1mm of tip travel sounds fine. It has no effect on accuracy and even a slight off-center primer hit is no biggie. It has slop so that any slight mis-alignment or crud won't tie the gun up; the firing pin wiggles "around" problems. Reliability goes up with no real downside.
As long as it isn't so bad that the pin sometimes misses it's hole on the way down and the gun doesn't go bang, enjoy. If you're worried at all, check the roll-pin holding it in by pushing on it with a toothpick or similar soft (plastic or wood) probe to make sure it's tight in the hammer. As long as it is, kewl. If it wants to roll or slide sideways under light pressure, PROBLEM...you need to press a new roll-pin in there. Buy the right size drift punch if doing it yourself!