The danger of shooting the low number 1903's is the subject of lengthy and heated debate any time it comes up. Some of the low numbers had receivers that were "burned" in the heat treating process. This would make them brittle and subject to failing in case of an obstruction in the bore or ruptured cartridge case. There is no test to determine whether the receiver is burned that does not destroy the receiver. When you have a lot of time, do a search for "low number 1903 Springfields" on the gun discussion forums and you will find many posts to read. The low number receivers were numbered 285,506 and lower from Rock Island Arsenal and lower than approximately 800,000 from Springfield Armory.