Some errata for this post.
I have, at this point, handled and examined no less than 7-10 1950 non-refurbished rifles and 'light' refurbished rifles.
By the end of 1950, they had dropped the spring loaded firing pin for the majority of production. If you have a 1950 with late features and a free floating firing pin, it can be an original. You must obviously look for the other signs of originality first.