Manuel costa de aeguibel
US 315746 A
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M. COSTA DE ARGUIBEL.
' Patented Apr. 14, 1885.
NirEE ErarEs arENr Erre MANUEL COSTA DE ARGUIBEL, OF BUENOS AYRES, ARGENTINE REPUBLIC.
SPECIFICATION 'forming part of Letters Patent; No. 315,746, dated April 14, 1885.
Application filed June 2, 1884.
T0 all whom it may concern:
Be it known that I, MANUEL CosTA D ARGUIBEL, a citizen of the Argentine Republic, residing at Buenos Ayres, in the said Argentine Republic, have invented certain new and useful Improvements in Riding Fire-Arms, of which the following is a specification.
My invention relates to iirearms, either held-pieces or small -ar1ns, of any character in which the bore of the barrel is ritled for the purpose of imparting a rotation to the ball; and my invention consists in the peculiar character of the riding, hereinafter fully set forth, whereby to prevent the strain of the arm in overcoming the inertia of the projectile, and to secure a greater initial velocity than results when the arm is rilied in Athe ordinary manner.
In the drawings, Figure 1 is a longitudinal section of the field-piece illustrating my invention. Figs. 2, 3, 4 are cross-sections upon the lines 1 2 3. respectively.
Billed fire-arms as heretofore constructed have been provided with riding-grooves of uniform depth, either extending from the breech to the outer end of the barrel or terminating abruptly at an intermediate point. In the first case there is apt to result an escape of gas,which lessens the full force of the explosion and the initial velocity of the pro- In the second case the shoulders formed by the abrupt termination of the rifling in the barrel scrape oif portions of the projectile. and result in clogging the barrel and interfering with the efficiency and accuracy of the piece. `In those cases where the projectiles fit with absolute accuracy the grooves at the rear of the bore, the gun is apt to be strained in overcoming` the inertia ofthe projectile. To avoid these objections, I provide the barrel with grooves of any ofthe ordinary forms,and arranged in any desirable manner, except that they terminate between the breech and the muzzle, and that they gradually decrease in depth from the breech to the point where they terminate, and then merge in the bore, which beyond such point is a smooth bore of uniform diameter. Thus in the piece illustrated in the drawings the grooves ce extend from the rear nearly to the line 3, and decrease gradually from the ordinary depth at the rear until they vanish at about such line into the (No model.)
bore, which from said line to the muzzle is a smooth bore. structed a soft-metal projectile or one provided with sabots adapted to be expanded to the bores by the force of the explosiomthere is a slight escape of gas at the instant of the explosion sufficient to relieve the strain which would result from absolutely confining the gas. The projectile or the sabot is forced into the grooves and fills the same by the force of the explosion, and the gradually-contracting diameter ofthe piece,resulting from merging the faces of the grooves into the bore, causes the projectile to be wedged more closely as it moves forward until it passes into the smooth bore, when it will be carried without any escape of gas, the result being that it will leave the muzzle with a much greater velocity than would be possible if the grooves were carried the entire length of the barrel.
Inasmuch as the grooves decrease gradually in depth, and there are no abrupt shoulders at the points where they terminate,there is no scraping of the projectile or clogging of the piece.
l am aware that it has been proposed to combine with the ordinary riding-grooves extending to the muzzle supplemental grooves decreasing in depth and terminating at about the middle of the barrel. My invention is distinguished from this by the fact that all the rifiing grooves terminate so as to leave a smooth bore beyond the ends of the said grooves.
I claiml. A re-arm provided with riding-grooves decreasing in depth from the breech toward the ends and merging into the bore, which is smooth beyond the ends of the grooves, substantially as described.
2. A tire-arm in which the riding-grooves all terminate and gradually vanish into the bore at the rear of the muzzle, which has a smooth bore between the end and the vanishing points of the. grooves, substantially as described.
In testimony whereof I have signed my name to this specification in the presenceof two subscribing witnesses. 4
MANUEL COSTA DE ARGUIBEL.
AUsrrN GALLAGEEE, GEORGE T. MUsGRAEL.
In using with a barrel thus con.