Historical Document · 1973
Theodor Koch's H&K patent on the fluted chamber (chamber relief grooves) of the roller-delayed guns (German priority 8 March 1967; issued 5 June 1973). The HK PSG1 dive cites it for why the chamber is fluted.
Q Unlted States Patent [191 1111 3,736,693 Koch 1451 June 5, 1973 [54] FIREARM BARREL 1751 Invenm" Them" 'K‘mh, (Neckar), Germany [73] Obemdmf 119,846 10/1871 Henry ..................................... ..42/78 1,165,621 121915 N 1 1,275,028 Assignee: Heckler & Koch GmbH, Oberndorf ‘ _ FOREIGN PATENTS OR APPUCATIONS . (Neckar), Germany . [22] Filed: Jan. 13,1971 [21] Appl. No.2 106,264 .......... ..42 7s 8/1918 1121:: .................................... “4257s 257 1/1864 Great Britain ..................... ..'_....42/7s 3,068 12/1860 Great Britain ............... ..42/78 270,630 1/1930 Italy ................. .. 605,136 7/1943 Great Britain ...................... ..42/76 R ....42/76 R Related US. Application Data [63] Continuation of’ Ser. No. 7ll,54?6,rrMarch 8, 1968, abandoned. Mar. 8, 1967 Germany .......................... ..H 62 052 US. Cl. ..................................... ..42/78, 42/76 R Int. Cl. .... ..F4lc 21/00, F41c 21/12, F4lf 17/10 Field of Search ............................... ..42/78, 76 R 45,898 [57] ABSTRACT The cartridge chamber of a firearm is provided with release grooves by virtue of polygonal shaping extend ing to a cylindrical sealing surface at the cap end of the cartridge. This pennits simpli?ed production as References Cited the chamber can be formed by forging at the same time that ri?ing of the barrel is effected. UNITED STATES PATENTS 12 Claims, 2 Drawing Figures [56] _ " ' Attorney—Craig, Antonelli, Stewart and Hill Foreign Application Priority Data [30] [52] [51] [53] Primary Examiner--Benjamin A. Borchelt Assistant Examiner-C. T. Jordan l/l 865 2” Berdan ................................... ..42/78 P1 PATENIEUJux 5197s 3.735.593 77/50 am BY INVENTOR Mac/7 6-4‘? 2 4‘. $1M ATTORNEYS 1 3,736,693 FIREARM BARREL This application is a continuation of application Ser. 'No. 711,546 ?led Mar. 8, 1968, and now abandoned. The invention relates to a ?rearm barrel especially for hand firearms, with a cartridge chamber embodying release grooves. The pressure developed within the cartridge case on ?ring a bullet tends to deform the cartridge case and therefore to press it tightly against the inner wall of the . cartridge chamber. Consequently the friction between the cartridge case and the cartridge chamber is so great that with automatic ?rearms satisfactory extraction of the case is no longer possible in many cases. In order 2 therefore possible with the barrel according to the in vention to ?re‘ a greater number of cartridges than with a barrel of known type. The line contact between the cartridge case and the barrel is also of advantage for ?r ing training cartridges of synthetic material since owing to the line contact the danger of a synthetic material cartridge jamming in the barrel owing to overheating is reduced. Also in this way the barrel according to the invention is preferable to the normal barrels. In order that the sealing of the cartridge chamber shall be fully maintained even with the barrel according to the invention, in a preferred constructional embodi‘ ment of the invention the polygonal pro?le of the car tridge chamber merges progressively into a circular to avoid such retention of the case the so-called release grooves are used which are grooves cut in the wall of profile which commences near the outer end of the car the cartridge chamber extending in the longitudinal di tridge chamber. Furthermore it is convenient for the rection of the chamber nearly to the base and in which approximate polygonal pro?le of the cartridge cham a counter pressure can be developed which hinders ad herence of the cartridge case to the wall of the car In this case it is possible to forge the ri?ing of the barrel tridge chamber. These release grooves have proved very effective but the production thereof is extremely dif?cult since they ber to have the same twist as the rifling of the barrel. 20 and the cartridge chamber in one working operation. The pro?le of the cartridge chamber advantageously has a greater number of corners than the barrel ri?ing since a greater number of release grooves distributed of very ?ne hook-like undercutting tools which must be around the periphery of the cartridge case has a better introduced into the narrow mouth of the barrel and by 25 effect. In many cases it is then convenient to choose the must be cut in the finished barrel. This requires the use ' which the grooves must be'cut chip by chip. It will be understood that cutting the release grooves number of corners of the pro?le of the cartridge cham ber so that is a simple multiple of the number of the ri ?ings provided in the barrel. is very time consuming, there being a relatively large Further details and constructions of the invention number of grooves distributed around the periphery of the cartridge chamber. Furthermore it is particularly 30 will be appreciated from the following description in which the invention is further described and explained difficult to maintain the necessary very close toler on the basis of the constructional example shown in the ances. These release grooves must in fact have not only drawings, and in which: a very accurate width and depth but they must com mence at an exactly de?ned point at the forward end FIG. 1 is a longitudinal section through the rear part of the cartridge chamber, must follow the tapered rear 35 of a barrel according to the invention and FIG. 2 is a section on the line [I — II through the bar ward enlargement of the cartridge chamber and must rel according to FIG. 1 on a larger scale. run out shortly in advance of the rear end of the car The barrel shown in the drawing embodies a drawn tridge chamber in order that the sealing effect of the case shall be completely maintained at its rear end. part 1 and a part 2 with the cartridge chamber 3 which is shaped in a single working operation by punching, The invention is directed to the problem of providing broaching or forging on a suitably pro?led mandrel. a cartridge chamber having release grooves, which is The drawn part 1 of the barrel is provided with approxi much more simple to produce and moreover has favor able properties compared with the known cartridge chamber. This object is attained according to the in vention by the fact that the cartridge chamber, just like the drawn part of the barrel, has approximately the mately polygonal rifle grooves as proposed heretofore. The approximate polygonal pro?le of the drawn barrel part 1 merges progressively into the approximate po lygonal pro?le of the cartridge chamber 3 as will be form of a polygon with rounded edges as seen in section and is so proportioned that the sides of the polygon are tangential to the cartridge case. seen from FIG. 2. It will be appreciated that such a cartridge chamber As shown in FIG. 2 the cartridge chamber 3 has a cross-section approximately in the form of a decagon with rounded corners and sides so proportioned that the side parts 4 of the cartridge case 5 are tangential as is much more simple to produce than a chamber which shown dotted in FIG. 1. I-Iollow spaces 7 are thus pro has a plurality of release grooves which must be cut in duced in the region of the corners 6 between the wall dividually. In particular such a cartridge chamber can be produced, in the same way as a barrel having a po 55 of the cartridge chamber 3 and the outer surface of the case 5, which act as release grooves. At the rear end of lygonal cross section, by means of a punch, drift or the cartridge chamber are approximate polygonal pro mandrel the cross section of which also corresponds to ?le merges, as indicated in FIG. 1, into a part 8 of the the internal cross section of the cartridge chamber. In length 9 of circular cross-section which permits the car this case all additional work for producing the release grooves is eliminated by the approximate polygonal 60 tridge to be sealed in the cartridge chamber on ?ring the shot in the desired manner. shape of the cartridge chamber formed. , The grooves formed by the rounded comers 6 of the Furthermore the approximate polygonal cross sec cartridge chamber 3 have the same twist as the ri?ing tion of the cartridge chamber has the further advantage in the barrel part 1 in the embodiment shown. Then a that the cartridges are only in line contact with the part of the barrel surrounding the cartridge chamber. Con 65 single mandrel, drift or punch can be used for forging the barrel, which has a portion corresponding to the sequently the transfer of heat between the barrel and cross-section of the drawn barrel with which portion the cartridge case is essentially reduced so that the dan ger of self'?ring of the cartridge is minimized. It is corresponding to the cartridge chamber is associated. 3 3,736,693 4 This mandrel or the like can be withdrawn rearwardly from the barrel after ?nishing the barrel. For producing the cartridge case. 4. In a firearm, the combination including a substan tially cylindrical cartridge case and a barrel comprising a barrel part and a cartridge chamber having approxi a smooth transition between the drawn part 1 of the barrel and the cartridge chamber 3 it is convenient if the number of corners of the pro?le of the cartridge mately a polygonal cross-section with the corners chamber is a simple multiple of the rifling. Then the ri thereof being rounded, and the approximate polygonal ?ing merges into corresponding parts of the polygonal shape'of the cartridge chamber selected so that the form of the cartridge chamber and it is su?icient to in sides thereof are tangential to the cylindrical cartridge clude further polygonal parts between these portions. case received therein and whereby release grooves are Thus the barrel shown in the drawing has ?ve rifling el formed. 5. The combination according to claim 4, wherein ements. It will be understood that the invention is not limited the barrel part has approximately a polygonal cross to the constructional example shown but variations are section with the corners thereof being rounded. possible without departing from the scope of the inven 6. In a ?rearm, the combination including a substan tion. Thus it will be understood that another shape of 15 tially cylindrical cartridge case and a barrel having a the cartridge chamber can be chosen according to the drawn barrel part and a cartridge chamber receiving type of weapon for which the barrel is to be used and the cylindrical case and embodying release grooves in which the cartridge chamber has substantially the the selection of a different number of release grooves is possible. It is also possible to utilize cartridge cham bers according to the invention for larger weapons and then the cartridge chamber may be brought to the de shape in cross-section of a polygon with the corners thereof being rounded and portioned so that the sides thereof are tangential to the cylindrical cartridge case received therein. 7. Barrel according to claim 6, wherein the approxi sired polygonal form by chip removal machining, for example by broaching or grinding. I claim: 1. In a ?rearm, the combination including a substan 25 mate polygonal cross-section of the cartridge chamber merges progressively into a circular pro?le which com menc'es near the outer end of the cartridge ‘chamber so as to form a gas seal at the base of the cartridge case. tially cylindrical cartridge case and a cartridge cham ber for receiving the cylindrical cartridge case, the car tridge chamber having approximately a polygonal 8. Barrel according to claim 6, wherein the drawn barrel part has the same shape as the cartridge cham cross-section with the corners thereof being rounded, and the approximate polygonal shape of the cartridge chamber selected so that the sides thereof are tangen ber. tial to the cylindrical cartridge case received therein and whereby release grooves are formed. 2. In a ?rearm, the combination including a substan provided with rifling and in which the approximate po 9. Barrel according to claim 8, wherein the barrel is lygonal pro?le along the cartridge chamber has the tially cylindrical cartridge case and a cartridge cham 35 same twist as the rifling of the barrel. l0. Barrel according to claim 9, wherein the cross section of the cartridge chamber has a great number of corners than the rifling in the barrel. ll. Barrel according to claim 9, wherein the number of corners of the cartridge chamber cross-section is a ber receiving the cylindrical case and embodying re lease grooves in which the cartridge chamber has sub stantially the shape in cross-section of a polygon with the corners thereof being rounded and portioned so that the sides thereof are tangential to the cylindrical cartridge case received therein. 3. The combination according to claim 2, wherein the approximate polygonal cross-section of the car tridge chamber merges progressively into a circular simple multiple of the-number of rifling elements pro~ vided in .the barrel. 12. Barrel according to claim 8, wherein the barrel part is provided with rifling in which said rifling is of ap pro?le which commences near the outer end of the car 45 proximately polygonal cross-section. tridge chamber so as to form a gas seal at the base of 55 60 65