Philadelphia, 18 July 1799 Sir, I have read with attention M^r Dana's letter— I think with him the proof of the Pistol Barrels as stated in the contract is unnecessarily severe— The Caliber of the Pistol is smaller than the Charleville Musket, the proof ball for the former is seventeen to the pound, of the latter fifteen, this at once determines the severity of the proof called for in the contract for the Pistols, as it is equal to the strongest proof required for Musket Barrels— The proof of the Musket barrels in Springfield was as is stated by M^r Dana made with one eighteenth part of a pound of powder, but it should be remembered that this proof was on finished work, whereas the proof called for in all our contracts is made when the Barrels are in the [underline: rough] after which they are materially reduced, and of course proportionally weakened— perhaps a proof of ⅛ part of a pound of Powder in that state is quite equal to 1/18 part in the rough State of the barrel— Having made these preliminary observations I am prepared to give my opinion, that one fifteenth part of a pound of Powder is sufficient for the first proof of the Pistols in question, and that a second proof is of very little use— The severest proof of the Musket where service ball is nineteen to the pound, and whose charge of Powder is about a thirty sixth part of a pound is one fifteenth part of a pound of Powder— the proof of a Pistol whose service ball is about twenty two to the pound (which is the size of those under contract) and whose charge of Powder is about the two and fortieth part of a pound should not by any rule of proportion exceed one eighteenth part of a pound— One principal cause why the Barrels burst in proving is, their being Welded on too large Mandrils or Stamps, by reason of which small boring which is laborious is very much diminished, the Barrels being reduced on the outside where the Welding is perfect and consequently much stronger: This was found to be the case in all the Barrels at first brought for proof to this City, the discovery has had the most salutary effect, for now not more than five per cent is lost in proving— Suitable Iron, and an attention to this particular will insure to the Manufacturer the reward of his labour— It is proper I should inform you that the Pistols making here being of smaller caliber than those under contract in Connecticut are proved with a charge of powder equal to one twenty second part of a pound— The foregoing is submitted as the result of experience and recent information.— I am, Sir, your most obedient Servant, Samuel Hodgdon James McHenry, Esq^r. Secretary of Wars.—