Odd thing I found out

[John Sukey (Deceased)]

Screw trhreads in trapdoors are METRIC

Information

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[5MadFarmers]

I thought they were Whitworth.

[tbeck]

Nope, they are English, but oddball sizes, and they use a non-standard thread profile similar to a Whitworth. Remember, there was no SAE, ISO or any other standards organization around in the 1870s, so Springfield designed the screws for Springfields. The thread patterns actually go back to at least the 1850s. M-1855 tang screws fit Trapdoors just fine, and the lockplate screws fit too, but they are too long. In fact, M1842 (and probably M-1816) trigger plate screws are identical to M-1 carbine buttplate screws, except for the finish.

[truckysm]

I thought I read that because our first rifles, M1795 Springfields, were copied from the French that the screws were the same as theirs. With no other standards they stayed that way for some time.

[5MadFarmers]

Nope, they are English, but oddball sizes, and they use a non-standard thread profile similar to a Whitworth. Remember, there was no SAE, ISO or any other standards organization around in the 1870s, so Springfield designed the screws for Springfields. The thread patterns actually go back to at least the 1850s. M-1855 tang screws fit Trapdoors just fine, and the lockplate screws fit too, but they are too long. In fact, M1842 (and probably M-1816) trigger plate screws are identical to M-1 carbine buttplate screws, except for the finish.

I was arse backwards.

Whitworth visited the US in 1854 during the arms tour that resulted in the Brits buying US equipment to make guns. The real start of Enfield Lock as a gun facility.

Whitworth derives from here, not vice-versa. I remembered Whitworth having something to do with US arms. Just remembered in reverse...

[Dan Shapiro]

The Model 1795 Springfield was copied from the French Charleville Musket (French Model of 1763). That was before the French Revolution and the introduction of the metric system.

[shjoe]

ah, the french metric system. i was unaware of that. do you know what they call a 1/4 pounder with cheese in france?

[tbeck]

On Enfield, James Burton went over to England in the 1850s from Harpers Ferry to set up their Armory on the US system of interchangeable parts. Before that, English arms were made by a bunch of contractors. Some would make barrels, others locks, others stocks and so on. They would send their parts in to the government for inspection. Those accepted would be reissued to fitting up shops for assembly, which always required a lot of hand work since the parts were not gauged to be interchangeable. Enfield armory changed that. Afterward, the contractors did mostly export and colonial trade work, while Enfield supplied part interchangeable arms to the crown. There is an interesting article from just before the Civil War on Burton's work in England. It's in Harpers Magazine, or Frank Leslies. After the war, Burton went over to Russia and did the same thing.

[BruceV]

ah, the french metric system. i was unaware of that. do you know what they call a 1/4 pounder with cheese in france?

Let me see... is it possibly "Le Big Mac?" Sincerely. Brucev.

[5MadFarmers]

Let me see... is it possibly "Le Big Mac?" Sincerely. Brucev.

See Pulp Fiction. Or maybe not, depending on your sensitivity level. The answer to that question is at the very beginning of the film.