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Re: Springfield Trapdoor Serial Number

Posted by Pete Nelson on Saturday, 19 February 2011, at 12:58 p.m., in response to Re: Springfield Trapdoor Serial Number, posted by Cary Meyers on Saturday, 19 February 2011, at 9:03 a.m.

Good afternoon Carey,

Thanks VERY MUCH for the Web Address of Tracy Tools, Ltd. I photocopied a bunch of the information on several sizes, especially the 5/32" x 26 tpi taps (Taper, Second, and Plug Taps and Dies). I have gone back and "re-visited" the table of the various sizes used by Springfield Armory to fill in a couple of gaps and re-check all of them.

I Appreciate the information very much. I'll be very interested in hearing how you make out with the taps.

I stumbled quite by chance onto a WebSite [www DOT practicamachinist DOT com] which had a response posted by a gentleman with a firm listed as "AV Ballistics Film Ordnance Services" in Brisbane, Australia who went into some detail on the history of the "...Springfield "Armoury" using the French metric system for the manufacture of the M1795 Springfield Flintlock Musket, as it was a derivation of the M1766 Charleville Musket of the Revolutionary War, as modified by the French Committee of Public Safet, St. Denis Aremory, to use a metric system pf threads, based on the earloier French system of 'Numbered Gun Threads' used by the Factories of Charleville, St. Etienne, and other French Armouries...".

He then goes on to say that "...The Springfield Armory thread system was rendered into 'inches' (thousandths of an inch) and this was used by Professor Sellars of Philadelphia to construct his Unified System Threads, presented to a conference of Engineers during the American Civil War (all inch dimensions and pitches, but with the metric 60-degree thread form)...".

"...The 'Springfield Metric" System was used up until the adoption of the Krag rifle in 1892, which was designed and made according to the Sellars Thread Scheme (Thread diameters, pitches, and sizes) so one will find some of the M1873/M1884 .45-70 guns will use truly metric screws, in exchange for the Springfield ones..." (?).

"...Given the sequential commonality of all the U.S. Thread Systems in gunmaking for military use, it is no great surprise that some modern screws will interchange with the more "ancient" ones...".

Very interesting posting, and it certainly warrants further reading. This whole question regarding "tghe Springfield System" has been addressed a number of times previously on this WebSite and has always piqued my own personal curiosity.

Thanks again for the information and very best regards,



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