In a nutshell:
The Magic Numbers are any rifle below 800,000 for Springfield Armory and 286,506 for Rock Island Armory. The reason these rifles are considered unsafe to fire is due to improper heat treatment when they were manufactured.The ammunition of the time was thought to be a contributing factor as well. The method of determining the proper heat treatment was less than scientific in that the men who were doing the heat treatment used the color of the steel to judge whether the correct temperature had been reached, When these rifles failed they shattered often causing injury to the shooter. Rifles manufactured after 800,000 and 286,506 received a double heat treatment and temperatures were measured with instruments rather than "by eye". Many of these original rifles were not withdrawn from service and are still on the market today.
Here's an interesting article on the subject:
http://m1903.com/03rcvrfail/
Last edited by Dan Shapiro; 02-24-2013 at 07:28.
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