I don't know where the 1.050-20 thread size come from because there is no such size.
I bought a 1.062-20 tap and threaded it right into a savage action and it fit perfect.
I think where the 1.050 size come from is every one measuring them with calipers and this is not the way you measure threads you do it with 3 wires and a micrometer to measure the thread pitch not the diameter.
The diameter can be quite a bit under size and still fit perfect.