The second half of your sentence first - abortion kills 100% of the time and sometimes kills the mother if done improperly.
A gun, if used properly or improperly has the ability to kill people. Likewise, a gun, if used properly, might go through it's entire existence as a gun without killing anyone. I've owned multiple guns for over 40 years and none of them have killed anyone. Who knows, though, someone could break into my home tonight and I and my gun would kill them, using the gun properly.