They could determine approximately velocity (as far as I am aware) by use of ballistic sledges or ballistic pendulums. As to whether or not electronic means of determining velocity were available, I don't know. I'd guess that work was going on in that direction at least, but as to whether or no any viable system that gave fairly accurate results was available then remains a guess to me without a bit of research via "Google" and its friends.
Also, as regards non electronic means, I'm led to believe that some systems used a series of spaced paper cards on a carefully set up range and measured drop between the cards and worked out velocity using Newtons Laws.
Vic Thompson.