As for the last in/first out for the bin scenario, how much production time did it take to fill up a bin? Hours? A day? Production at this time was 120 rifles per day. I doubt there would be 120 receivers in a given bin. But it's possible.

I need to get the 5MadFarmers book if it is still available. I did find a year old posting of his from another forum. In it he said:
"What is a magazine rifle? A Krag from about 19k to 24k. Basically a M-1892 with ever increasing M-1896 features."
In one of my earlier posts above, from the Expenditures at the Springfield Armory it lists some alterations done, fiscal year ending 6/30/1897:
3,508 magazine rifles altered to model 1896
2,800 magazine rifles, model 1892, altered to model 1892, second pattern
It is strange that in the first line the rifle is referred to only as a magazine rifle. I am starting to become a believer in 5MadFarmers theory of the "magazine rifle" to describe these in-betweeners. But once altered, I believe they would be recognized by the military as M1896.