US2935912A - Erosion-and-corrosion-resistant gun barrel adapted to hold a coolant - Google Patents

Description

May 10, 1960 J. c. HARTLEY EROSION-AND-CORROSION--RESISTANT GUN BARREL ADAPTED TO HOLD A COOLANT s sheets-sheet 1 Filed Oct. 11, 1950 n 2 1.. .uw 5 3 9, 2 L m R A B m mm NL YAo Emw mA RR C. HA OSION- TO HOLD D mmm. E D mm v o I S o R E 0 6 9 l 0, l y Ma 3 Sheets-Sheet 2 Filed Oct. 11, 1950 s a. .y .M\\\\\\\\\\\ @We ma www@ mw. @u

May 10, 1960 J. c. HARTLEY EROSION-AND-CORROSION-RESISTANT GUN BARREL ADAPTEZD TO HOLD A COOLANT 3 Sheets-Sheet 3 Filed OCbl1, 1950 NW- @Lr S @NIJ wm w@ IJ v il s ,Ii

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' EROSION-AND-CORROSION-RESISTANT GUN j BARREL ADAPTED TO HGLD A, COOLANT James C. Hartley, Branford, Conn., assigner to Olin Mathieson Chemical Corporation, a corporation of Virginia Application october 11, 195o, serial No. 189,643

so claims.y (ci. ssi-14.1)

This invention relatesto gun-barrels in general, and to gun-barrels for rapid-fire arms in particular.

.v It is one of the main objects of the present invention to provide a gun-barrel which has greater resistance, to the erosive and thermal effects of ring than was here-- tofore attainable, thereby lending a longer useful life to-v` theVgun-barrel and rendering it suitable especially, though not exclusively, for use in weapons of high cyclic 'firing rates.

It is another object of vthe present invention to devise a method of, and make provisions for, cooling a gun-barrel more effectively and at a fasterVV heat-exchange rate than heretofore, thereby to reduce the erosive and corrosive effects of firing on the gun-barrel to a minimum and permit effective ring, even at high cyclic rates, over a longperiod of time without overheating the barrel or entailing unduly rapid wear of the same.`

fAAfurther object of the present invention is to bring av fluid-coolant into direct heat-exchange relation with a gun-barrel throughout the cross-sectional area of the lat- 1 further, byforcing controlled quantities of the aforementioned internal coolant in the gun-barrel into the bore thereof wherein the coolant will form a thin protective film or coat which eifectively reduces heat-transmission.

, into the barrel andsubstantially isolates a projectile there` 45 in from the bore thereof. A t jIt is still ya further object of the present invention to provide a gun-barrel which is especiallysuited foruse in rapid-fire arms, such as machine guns and other ordnancev of high cyclic tiring rates, and which requires replacement Vmuch less frequently than previous gun-barrels in ordnance of this type. A' f Y 'It-is also among the objects of the present invention to provide a superior erosion-and-corrosion-resistant gunbarrel of this type which, while exceedingly simple and sturdy in construction, is nevertheless highly accurate'and v reliable in its performance, and readily lends itself to etlicient mass production at relatively low cost.

Other vobjects and advantages -will appear to those skilled in the art from the following, considered in conjunction with the accompanying drawings.

In the accompanying drawings, in which certain modes of carrying out the present invention are shown Yfor illustrative purposes: Fig. l is a fragmentary side elevation, partly in section, of a gun-barrel embodying the present invention;

Fig. 2 isV a" fragmentary longitudinalv section through the same gun-barrel;

Figs. 3 and 4 are fragmentary cross-sections throughV the gun-barrel as taken on the lines 3-3 and 4-,4, re-' spectively, of Fig. 1; Y p KK Y A O l-Figs. 5 and 6 perspectively illustrate a prominent detail `lice element of the instant gun-barrel, as viewed from different l gun-barrel, as taken on the lines 9-9 and 10-10, re-

Fig. -11 is a fragmentary longitudinal section, partly in elevation, of a gun-barrel embodying the'present invention in a further modified manner;

Fig. 12 is a fragmentary longitudinal section through the modified gun-barrel of Fig. 1l; and

Fig. 13 is a section taken on the line Y1313-of Fig. 12.

nReferring to the drawings, and more yparticularly to Figs. 1 and 2 thereof, Ythe reference numeral 10 designates a gundbarrel unit or assembly which comprises, in the present instance, a gun-barrelY 11 and a jacket 12 which peripherally surrounds the latter and is adapted Vfor holding a fluid-coolant. The gun-barrel 11 is in the form of a tubular member 13 which is provided Iat its Arear end with a cartridge-chamber 14 and, in the present instance, also with a largelongitudinal bore 15 that extends to the' The breech-ange 19-and the muzzle-cap 20 may con-Y veniently be tightly screwed over the rear and front ends, respectively, of the barrel-member 13. The outer tube 18 is retained between the breech-flange 19 and the muzzle-cap 20, preferably in hermetically-sealed relation therewith by being, for inst-ance, Welded thereto as at 21 and 22, respectively. The tube 18 is providedV with an inlet 23 to provide communication, through intermediation of a conduit 24, between the interior ofthe jacket 12 and a source of any suitable fluid-coolant under pressure. The jacket 12 may also be provided with spacedtransverse partitions 25 which, in this instance, are in the form of rings that are suitably secured to the tube 18 and barrel-member 13. Thepartitions 25 in the jacket 12 are perforated yat 26y (see falso Figs. 3 and 4) to provide communication in the jacket throughout its longitudinal extent. Theperipheral wall 27 of the barrelmember 13 s, within the longitudinal confines of thebore 15 therein, provided with a multitude of perforations orducts 28 which provide communication between the bar-` rel-bore 15 and the interior of the jacket 12. The breech-V flange 19 is preferably externally threaded as at 19a for the assembly of Ythe instant gun-barrel unit with a receiver ,R.

Thebore 15 in the barrel-member 13 is, in accordance alignment with each other by being provided,for instance, with interiitting ends 31 and 32, respectively ('Figs. 2, 5 and 6). Theinserts 30 Iare also provided with longitudinal, preferably ried bores 33, respectively, which collectively form theV projectile-bore 34V of the gun-barrel 11. Any suitable provision may be made to .hold theinserts 30 against rotation relative to each other.

To this end, theinserts 30 are, in the present instance, provided with intertitting'tongues and groovesfSlafand 32a, respectively (Figs. 5` and 6).

Y It is the intended function of the porouslinerl the barrel-member 13 to conduct uid-coolantnd'er" l 2,935,912 f f Peretti .Meyn 1.9m

pressure from the jacket 12 through theporous inserts 30 to the wall of the projectile-bore 34 for effectively cooling the same, and thereby greatly reducing the adverse erosive and corrosive eiects from ring the gun on the gun-barrel 11. Thus, coolant under pressure will pass from the jacket 12 through theperipheral perforations 28 in the barrel-member 13 and Will seep through theporous inserts 30 to the Wall of the projectile-bore 33, accomplishing thereby the most elective direct heatexchange between a coolant and the hottest part of a gun-barrel, i.e., the wall of its bore. In thus bringing the coolant into direct heat-exchange relation with theinserts 30 throughout their cross-sectionall areasV and, hence, also with the Wall of the projectile-bore 34, the adverse erosive and corrosive effects on the instant gunbarrel are greatly reduced, so much so that the gunbarrel will safely withstand tiring, even at high cyclic firing rates, for an unusually long period of time without becoming dangerously overheated or worn unduly rapidly. The instant gun-barrel unit is, therefore, ideally suited for use in firearms having high cyclic firing rates, such as machine guns, sub-machine guns, or even larger rapid-lire ordnance.

Theinserts 30, which make up the liner 29 in the barrel-member 13, may be made of any suitable 'porous material. For instance, theinserts 30 may be made from suitable powdered materials which in their compacted form are porous Within the limits desired and best suited for the purpose in mind. Among the many materials suitable for this purpose, there may be mentioned Stellite alloys, such as Vitallium, for instance, stainless steel, molybdenum, etc., :also ceramals which are ceramic-metallic combinations, mainly borides of tantalum, chromium, etc.

Given only by way of example and by no means by way of limitation, the following is an an-alysis of an insert actually produced and found to possess satisfactory porosity and other desirable properties. Thus, an insert, such as theinsert 39, was made from Vitallium, comprising approximately 65% by weight of Co, 27% by weight of Cr, 6% by weight of Mo, all in powdered form, and smaller quantities, also in powdered form, of Si, C, Mn and Fe.

The above-mentioned Vitallium insert was compacted under a pressure of 40 tons per square inch, and then sintered for two hours ata temperature of 2100 F. The porosity of this insert was found to be approximately 32%.

The possible coolants employed in the instant gunbarrel unit 10 may lbe either gaseous or liquid. Among the many gaseous coolants that may be used, there may be mentioned, by way of example only, air, argon, helium, nitrogen, carbon dioxide, etc. Among the many liquid coolants useable for this purpose, there may be mentioned, also by way of example only, water, suitable petroleum derivatives, such as kerosene, etc.

As previously explained, coolant in the jacket 12, whether in gaseous or liquid form, will, by reason of being under pressure, penetrate theporous inserts 30 to the wall of thebore 34 therein, thereby not only cooling the entire inserts, including the wall of thebore 34 therein, most effectively, but also forming on the Wall of the bore 34 a lm or layer which prevents the hot powder gases from effectively contacting the wall of the bore 34.-, and also acts yas a spacer between the latter and a traveling projectile therein, thereby reducing erosion of the wall of the projectile-bore 34 even further.

The high pressure in the projectile-bore 34, resulting from the lfiring of each cartridge, will displace, or tend to displace, the internal coolant in theinserts 30 nearest the cartridge-chamber 14, outwardly to a greater or lesser extent, depending on the permeability of the inserts, the viscosity of the coolant, and the peak-value of the pressure of the explosion of a tiring charge. 'I'he high pres- -sure in the projectile-bore 34, resulting from the explosion of a firing charge, lasts only momentarily, and there is sucient time between shots, even when Ifired in rapid succession, to permit restoration of the pressure in the projectile-bore 34 to `atmospheric or substantially atmospheric pressure. Thus, during approximately 75% of the time a rapid-fire arm is being fired at 1000 shots per minute, for instance, no explosions take place in the gun-barrel thereof. Hence, since the high pressure Vin the projectile-bore in consequence of firing a cartridge lasts only momentarily, and atmospheric, or substantially atmospheric pressure will be restored in theprojectilebore 34 soon after tiring each cartridge, the internal coolant in theinserts 30 will, under its own pressure, reverse, or tend to reverse, its flow therein soon after Ifiring a cartridge. Hence, theporous inserts 30, especially those nearest the cartridge-chamber 14, act much in the manner of a pulsating pump when the gun is in operation, with the coolant in the inserts elfectively cleaning the latter and preventing their clogging with the waste products of the powder combustion. As an additional pre- -cautionary provision, the conduit 24 may be provided with a check-valve 36 (Fig. l) which opens only for the admission of coolant under pressure into the jacket 12.

By reason of the high temperatures prevailing in thebore 34 in consequence of tiring cartridges, a liquid-type coolant on the wall of thebore 34 and also in theinserts 30 near the bore-wall, will be vaporized and the requisite latent heat of vaporization will accordingly reduce the temperature on the wall of thebore 34, as will rbe readily understood. Hence, while a liquid-type coolant will remain in liquid form in more or less of the cross-sectional area of the inserts 36, the coolant film onV the Wall of thebore 34, will be in vaporized form and electively isolate a projectile from the wall of thebore 34. Further, the pulsating liquid-type coolant in theporous inserts 30 acts as a check-valve which prevents the products of combustion in thebore 34 from passing through these inserts into the jacket 12, as will be readily understood.

Reference is now had to Figs. 7 and 8 which show a modified gun-barrel unit 37, having a gun-barrel 38 and a coolant-jacket 39 which, in this instance, surrounds only a length of the gun-barrel 38, including the rear end thereof. Provided in aninsert 40 in the rear end of the barrel 38 is a cartridge-chamber 41 which is in coaxial alignment with anenlarged bore 42 in the barrel 38. The enlarged bore 42 extends, in the present instance, only over a part of the longitudinal extent of the barrel 38, and is continued to the front of the latter as a diametrically-reduced, preferably rifledpart 43 of the projectile-bore in the instant gun-barrel. The enlarged bore 42 in the barrel 38 serves for the reception of aliner 44 to be described hereinafter.

Thejacket 39 is formed by an outer tube 45, and endflanges 46 and 47 which are suitably secured to the barrel 38 as at 48 and 49 respectively. Preferably, thejacket 39 is also provided withtransverse partitions 50 which are perforated at 51 to provide communication inthc jacket 39 throughout its longitudinal extent. The peripheral wall 52 of the barrel 38 is also provided with a multitude ofperforations 53 which provide communication between the interior of thejacket 39 and the enlarged bore 4Z in the barrel 38. Thejacket 39 is also provided with an inlet 54 through which to admit coolant under pressure from any suitable source through intermediation of aconduit 55 which, as shown in Fig. 7, may be provided with a check-valve 56.

Theliner 44 comprises a plurality of longitudinalporous inserts 57 and interposed spacer-ribs 5S, respectively. Theinserts 57, which may be made of similar materials and in a similar manner as the previouslydescribed inserts 30, are cross-sectionally shaped like sectors (Fig. 9) which are truncated at 59 to form the remainingpart 60 of the projectile-bore in the gun-barrel 3.8. Theinserts 57 and spacer-ribs' 58 extend longitudinally of the gun-barrel 38 in the spiral fashion shown in Figs.' 7 and 8, and the spacer-ribs 58 extend radially inwardly of the Apart 60,0f the'projectile-bore suficiently Yto form the rifling 61 therein. The riing 61 is so arranged that itslands 62 are in alignment with the lands 63 ofthe rifling in theforward part 43 of the projectile-bore in the gun-barrel 38 (Fig. 8). The spacer-ribs 58 need not be porous, and are preferably of steel or other materials suitable for the purpose.

While the instant modified gun-barrel unit 37 has aporous liner 44 which extends only over a part of the longitudinal extent of the gun-barrel 38, it is fully within Y the purview of the instant invention to extend theporous liner 44 throughout the longitudinalr extent of the gunbarrel 38, in accordance with the showing of the porous liner 29 in the earlier described gun-barrel unit 10. It is also fully within the` purview of the instant invention to extend the liner 29 of the earlier described gun-barrel unit 10 over a part only of the longitudinal extent of the barrel-member 13 thereof in accordance with the showing of the modified porous liner 44'1`n thegunbarrel unit 37. It is further within the purview of the present invention to make each of theliners 29 and 44 in one piece. In that event, theribs 58 are molded in theliner 44 when the same is formed, theribs 58 preferably terminating ,short of the liner periphery so as to be embedded in the liner. Further, theinserts 30 may, for the formation of the riiling in thebore 34 thereof, be provided with n molded-inV steel ribs (not shown).

Figs. lljand 1,2` vshow aV further modified gun-barrel unit 64 which, with the exception of a single-piece porous liner 65 with a non-rifled. bore 66 and nonperforatedtransverseV partitions 67 in thejacket 68, may essentially belike the previously described gun-barrel unit 37. In

the present instance, the requisite rifling 69 for spinning` a discharged projectile is provided vin theforward part 70 of the projectle-borein the gun-barrel 71 of the unit.

Thenonperforated partitions 67 in thejacket 68 divide the latter into separate chambers or compartments'72, respectively, which are in individual communicating relation with the porous liner 65 through peripheral perforations orducts 73 in the gun-barrel 71.lEach ofthe chambers 72 is in individual communication with a suitableV source of coolant under pressure through intermediation ofconduits 74, respectively, and interposed in eachconduit 74 is avalve 75 which may -be controlled ,Y manually for admitting more or less coolant under press ure in totherespective chamber 72. Eachvalve 75 may,

l if desired, be of the adjustable pressure-reduction type.

By dividing the jacket 68- intotheseparate chambers 72 and, interposing thevalves 75 ,inthe respective conduitsv74, coolant under dilferent pressures and/or of dif..

' ferentamounts may be admitted intothefdifferent chambers 72, therebyproviding'the mechanism foremost-etlicient andreconomical use of the coolant'. Thus,more coolantper time unit, preferably also under-higher pressure, may be admitted into thechambers 72 nearest the cartridge-chamber 76 than into the chambersmore re-' mote from the latter, thereby to cool the hottest part of the projectileebore more intensely than the remaining part thereof.

. VIn lieu of thevalves 75 andconduits 74, the jacket' 68 may in itstransverse partitions 67 be provided with checktype valves, respectively (not shown), which are springloadedto admit coolant from one chamber V72, into the chamber adjacent thereto only after the pressure of the, coolantin the former chamber exceeds a predetermined, maximum. In `'this event, onlythev chamber 72a nearest v Y thecartridge-chamber 76 need Vbe in communicationwith lthe vsource of'coolant underV pressure through the conduit 74a'.V By thesel provisions, the lcoolant in .thechamber 72a may be under maximum pressure, whilethe coolant inthechambers l72y progressively more remote from the latter may be'under-progressively lower pressures,

Y vThe terni porous as used hereinbefore' and in' thealv in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency vrange of the appended claims are intended ito be embraced therein.

I claim: 1. AnV erosion-and-corrosion-resistant gun-unit, comprising la gun-barrel having an outer circumference and al longitudinal projectile discharge bore and being, Vat leastY over a length thereof, porous from s'aid outer circumference to said projectile discharge bore; and an outer jacket surrounding the porous circumference of said barrellength and forming therewith a chamber adapted to hold coolant for penetration into said porous lbarrel-length to the projectile discharge bore thereof.

2. An erosion-andcorrosionresistant guniunit, comprising a gum-barrel having an outer circumference and a longitudinal projectile discharge bore and being, at least over a length thereof, porous from said outer circumference to said projectile discharge bore; and an outer jacket surrounding the porous circumference of said barrel-length and forming therewith Ia chamber, said jacketV having an inlet for coolant under pressure for its forced penetration',y

from said chamber into said porous barrel-length to the projectile discharge bore thereof.

3. An erosion-and-corrosion-resistant gun-unit, comprising a gun-barrel having alongitudinal projectile discharge bore and being, at least over a lengththereof,

porous substantially throughout its crosslrsectional area; and an outer jacket surrounding said Ibarrel-length andV forming therewith a chamber adapted to hold coolant for penetration into said porous barrel-length to the projectile discharge bore thereof.

4. An erosion-and-corrosion-resistant gun-barrel unit, v

comprising a shell having a peripheral wall provided with perforations; a porous liner in said shell, said liner having,

a longitudinal projectile discharge bore; andan outer jacket surrounding the peripheral Wall of said shell and adaptedto hold coolant `for passage through `said per,

perforations; a porous liner in said shell, said hner having a longitudinal projectile discharge bore and being formed by a plurality of inserts in said shell; andanouter jacket surrounding the peripheral wall of said shellandadapted to hold coolant for passage through said perforations andv penetration into said porous liner to the projectile discharge bore thereof.

7. An erosion-and-corrosion-resistant gun-barrel unit,- comprising a shell having a peripheral wall provided with: perforations; a porous liner in said shell, said liner being formed by Ya plurality of end-toend arranged porous inserts in said shell having riiied bores, respectively, which Y form a continuous ried projectile discharge bore in said liner; and an outer jacket surrounding the rperipheral wall of said shell and adapted to hold coolant for passage;vv through said perforations and penetration into said porous liner to the projectile discharge bore thereof.

8. An erosion-and-corrosion-resistant' gun-barrel unit;

comprising a shell having a peripheral wallprovided .with` perforations; a porous liner in said shell, said liner having a longitudinal projectile discharge bore and being formed by a plurality of end-to-end arranged porous inserts'in said shell; and an outer jacket surrounding the peripheral Wall of said shell and adapted to hold coolant for passage through said perforations and penetration into said porous liner to the projectile discharge bore thereof.

9. An erosion-and-corrosion-resistant gun-barrel unit, comprising a shell having a peripheral wall provided with perforations; a porous liner in said shell, said liner having a longitudinal projectile discharge bore and being formed by a plurality of end-to-end intertted porous inserts in said shell; and an outer jacket surrounding the peripheral Wall of said shell and adapted to hold coolant for passage through said perforations and penetration into said porous liner to the projectile discharge bore thereof.

l0. An erosion-and-corrosion-resistant gun-barrel unit, comprising a shell having a cylindrical Wall provided with perforations; a liner in said shell, said liner having a longitudinal projectile discharge bore and being formed by a plurality of complemental porous inserts of cross-sectional truncated sector shapes, respectively, and interposed spacers, respectively, in said shell; and an outer jacket surrounding the peripheral wall of said shell and adapted to hold coolant for passage through said perforations and penetration into said porous inserts to the projectile discharge bore in said liner.

11. An erosion-and-corrosion-resistant gun-barrel unit as set forth in claim l0, in which said inserts and spacers extend spirally in the longitudinal direction of said shell, and said spacers are of steel and extend inwardly slightly beyond the adjacent inserts, respectively, to form the riing in said projectile discharge bore of the liner.

lf2. An erosion-andcorrosion-resistant gun-barrel unit, comprising a shell having a peripheral Wall provided with perforations; a porous liner in said shell and having a longitudinal projectile discharge bore; and an outer jacket surrounding the peripheral wall of said shell and adapted to hold coolant for passage through said perforations and penetration into said porous liner to the projectile discharge bore thereof, said liner being formed by a plurality of porous inserts, including nonporous steel ribs, in said shell, of which said steel ribs extend radially into said projectile discharge bore and spirally longitudinally of the latter to form the riiling in said projectile discharge bore.

13. An erosion-and-corrosion-resistant gun-barrel unit, comprising a gun-barrel having a cartridge-chamber in its rear end and a cross-sectionally enlarged longitudinal bore extending to said cartridge-chamber, and being provided in its peripheral wall with perforations in commu nication with said bore; a porous liner in said barrelbore, said liner having a longitudinal projectile discharge bore in line with said cartridge-chamber; and an outer jacket surrounding the peripheral wall of said gun-barrel and adapted to hold coolant for passage through said perorations and penetration into said porous liner to said projectile discharge bore therein.

14. An erosion-and-corrosion-resistant gun-barrel unit as set forth in claim 13, in which said porous liner is formed by a plurality of inserts in said barrel-bore.

l5. An erosion-andcorrosion-resistant gun-barrel unit as set forth in claim 13, in which said porous liner is formed by a plurality of end-to-end arranged porous inserts in said barrel-bore.

16. An erosion-and-corrosion-resistant gunbarrel unit as set forth in claim 13, in which said liner is formed by a plurality of porous inserts, including nonporous steel ribs in said barrel-bore, of which said steel ribs extend radially into said projectile discharge hore and spiral- 1 17. An erosion-and-corrosiomresistant gun-barrel unit,

comprising a gun-barrel having a cartridge-chamber in its rear end and a longitudinal bore of 'which an end=length at the front of said barrel forms a part of the projectile discharge bore of the latter and the remaining length extends to said cartridge-chamber and is cross-sectionally enlarged, said gun-barrel having a peripheral Wall provided with perforations in communication with said enlarged bore-length; a porous liner in said enlarged borelength in said barrel, said liner having a longitudinal bore in line with said cartridge-chamber and with said end-length of said barrel-bore and constituting the remaining part of the projectile discharge bore in said gunbarrel; and an outer jacket surrounding the peripheral wall of said gun-barrel and adapted to hold coolant for passage through said perforations and penetration into said porous liner to said bore therein.

18. An erosion-and-corrosion-resistant gun-barrel unit as set forth in claim 17, in which said porous liner is formed by a plurality of inserts in said enlarged borelength in said gun-barrel.

19. An erosion-and-corrosion-resistant gun-barrel unit as set forth in claim 17, in which said end-length of the bore in said barrel is ried.

20. An erosion-and-corrosion-resistant gun-barrel unit as set forth in claim 17, in which said end-length of the bore in said barrel is rifled, and said liner is formed by a plurality of porous inserts, including nonporous steels ribs, in said enlarged bore-length in said gun-barrel, of which said steel ribs extend radially into said liner-bore and spirally longitudinally of the latter to form the riing in said liner-bore in continuation of the riing in said end-length of said barrel-bore. 1

2l. An erosion-and-corrosion-resistant gun-barrel unit, comprising a shell having a peripheral wall provided with perforations; a porous liner in said shell, said liner having a longitudinal projectile discharge bore and nonporous steel ribs extending radially into said projectile discharge bore and spirally longitudinally of the latter to form the riing in said projectile discharge bore; and an outer jacket surrounding the peripheral wall of said shell and adapted to hold coolant for passage through said perforations and penetration into said porous liner to the projectile discharge bore thereof.

22. An erosion-and-corrosion-resistant gun-barrel unit, comprising a shell having a peripheral Wall; and a porous liner in said shell, said liner having a longitudinal projectile discharge bore and said peripheral shell-wall being apertured for the passage of coolant to said porous liner and penetration of the coolant into the latter to the projectile discharge bore thereof. A

23. An erosion-and-corrosion resistant gun-barrel unit `as set forth in claim 22, in which said porous liner is formed by a plurality of inserts in said shell.

24. An erosion-and-corrosion-resistant gun-barrel unit as set forth in claim 22, in which said liner has nonporous steel ribs extending radially into said projectile discharge bore and spirally longitudinally of the latter to form. the riiling in said projectile discharge bore.

25. An erosion-and-corrosion-resistant gun-barrel unit, comprising a shell having a peripheral Wall; and a porous liner in said shell, said liner being formed by aY plurality of end-to-end arranged porous inserts in said shell having ried bores, respectively, which form a continuous ried projectile discharge bore in said liner, and said peripheral shell-wall being apertured for the passage of coolant to said porous liner and penetration of the coolant into the latter to said projectile discharge bore thereof.

26. An erosion-andcorrosion-resistant gun-barrel unit, comprising a gun-barrel having a cartridge-chamber in itsrear endVv and a cross-sectionally enlarged longitudinal bore extending to said cartridge-chamber; and a porous j liner in said barrel-bore, said liner having a longitudinal projectile discharge bore in line with said cartridgechamber, and said gun-barrel having a peripheral wall which is apertured for the passage of coolant to said porous liner and penetration of the coolant into the latter to said projectile discharge bore thereof.

`extends to said cartridge-chamber and is cross-sectionally enlarged, said gun-barrel having a peripheral wall provided With an aperture in communication with said enlarged bore-length; and a porousV liner in said enlarged l bore-length in said barrel, said liner having a longitudinal bore in line With said cartridge-chamber and with said end-length of said barrel-bore and constituting the remaining part of the projectile discharge bore in said gunbarrel, and said aperture in said peripheral barrel-wall serving for theA passage of coolant to said porous liner and penetration of the coolant into the latter to said bore therein.

28. An erosion-and-corrosion-resistant gun-unit, comprising a gun-barrel having an outer circumference and a longitudinal projectile discharge bore and being, at least over `a length thereof, porous from said outer circumference to said bore; and an outer jacket surrounding the porous circumference of said barrel-length and forming therewith a chamber, said jacket having transverse partitions spacedflongitudinally of said barrel-length and dividing said chamber into separate compartments which are in individual communicating relation with the porous circumference of said barrel-length, and each of said compartments having an inlet for a coolant for its penetration into said porous barrel-length to the projectile discharge bore thereof.

29. An erosion-and-corrosion-resistant gun-barrel unit, comprising a shell having a peripheral wall provided with perforations; a porous liner in said shell, said liner having a longitudinal projectile discharge bore; and an outer jacket surrounding the peripheral wall of said shell, 'saidk jacket having |transverse partitions dividing the same longitudinally of said shell into separate chlamberspwhich are in individual communicating relation with', said liner through said wall-perforations, and each of said Ychambers having an inlet for a coolant for its passage through said perforations and penetration into said liner to the projectile discharge bore thereof.

30. An erosionand-corrosionresistant gun-barrel unit as set forth in claim 29, further comprising valves in said inlets, respectively, for the admission of variable amounts of coolant into the respective chambers.

References Cited in the le of this patent UNITED STATES PATENTSVV 797,237 Smith Aug. 15, 1905 1,856,304 Whitely May 3, 1932 2,315,467 Wahlberg a Mar. 30, 1943 2,406,891 Newton Sept. 3, 1946 2,494,023 Williams Jan. 10, 1950 FOREIGN PATENTS 4,1095 Switzerland Sept. 28, 1891 540,865 Great Britain Nov. 3, 1941V

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