US3721792A - Apparatus for burn-fitting wooden gun stocks to metal receivers - Google Patents

Abstract

METHOD OF, AND APPARATUS FOR, FULLY SEATING ON A RECEIVER END THE ENDS OF TANGS ON A WOODEN GUN STOCK, OF WHICH THE STOCK TANGS ARE PARTIALLY INTERPROJECTED WITH RECEIVER TANGS ON THE RECEIVER END, AND HAVE EXCESS WOOD INTERFERING WITH THEIR FULL INTERPROJECTION WITH THE RECEIVER TANGS, WITH THE PARTIALLY INTERPROJECTED RECEIVER AND STOCK BEING PLACED IN A HOLDING FIXTURE, AND ONLY PART OF THE HELD RECEIVER THEREIN, INCLUDING ITS END, BEING SUBJECTED TO HIGH-FREQUENCY INDUCTION HEATING TO STOCK-BURNING TEMPERATURE, WHEREUPON THE STOCK IS DRIVEN INTO FULL INTERPROJECTION WITH THE HELD RECEIVER TO THE EXTENT OF A COMPLETE BURN-FIT OF THE STOCK TANG ENDS WITH THE RECEIVER END.

D R A W I N G

Description

March 20, 1973 5. J. MORRIS ET AL 3,721,792

APPARATUS FOR BURN'FITTING WOODEN GUN STOCKS TO METAL RECEIVERS Original Filed June 4, 1971 2 Sheets-Sheet 1 March 20, 1973 5. J. MORRIS ET AL 3,721,792

APPARATUS FOR BURN-FITTING WOODEN GUN STOCKS TO METAL RECEIVERS Original Filed June 4, 1971 2 Sheets-Sheet 2 United States Patent 3,721,792 APPARATUS FOR BURN-FHTTING WOUDEN GUN STOCKS T0 METAL RECEIVERS Stephen J. Morris, North Haven, and James M. OKeefe, Cheshire, Conm, assignors to The Marlin Firearms (10., North Haven, Conn.

Original application .iune 4, H71, Ser. No. 149,964, new Patent No. 3,697,715. Divided and this application May 25, 1972, Ser. No. 257,004

lint. Cl. 110% /08 U.S. Cl. Z19-ltl.57 4 Claims ABSTRACT OF THE DISCLOSURE Method of, and apparatus for, fully seating on a receiver end the ends of tangs on a wooden gun stock, of which the stock tangs are partially interprojected with receiver tangs on the receiver end, and have excess wood interfering with their full interprojection with the receiver tangs, with the partially interprojected receiver and stock being placed in a holding fixture, and only part of the held receiver therein, including its end, being subjected to high-frequency induction heating to stock-burning temperature, whereupon the stock is driven into full interprojection with the held receiver to the extent of a complete burn-fit of the stock tang ends with the receiver end.

This invention relates to fitted gun stocks and receivers in general, and to a method 'of, and apparatus for, fitting stocks to receivers in particular.

This application is a division of our copending application Ser. No. 149,904, filed June 4, 1971, now Pat. No. 3,697,715.

The present invention is concerned especially, though not exclusively, with a widely used type of rifle of which the receiver and stock have, for their firm and lasting mount on each other, interprojected and locked tangs and also backing shoulders for the ends of the interprojected tangs. A fairly good fit of the interprojected tangs is but one of the requirements of a rifle of attractive appearance and good workmanship, but a particularly accurate fit between the tang ends and their backing shoulders is imperative for additional high functional quality, in that these shoulders must seat the receiver on the stock with that accuracy at which the latter will evenly take up all recoil shock and thus obviate any possibility of stock splitting. While a fairly good fit of the interprojected tangs may be obtained, either by minimal and relatively simple hand-fitting of the machined stock tangs to the receiver tangs, or by machining the stock tangs to dimensions at Which they adequately interfit with receiver tangs without any hand-fitting, the backing shoulders will not afford the required accurate seats for receivers without additional stock fitting.

Accurate fitting of wooden parts to metal parts by burnon of the latter to the former is an old expediency, for example in fitting wooden handles to the stems of metal tools by heating the stems and ramming them into undersized holes in the handles. This expediency has also been resorted to in the gun art in interfitting stocks and receivers of the described type. Thus, there is known a method of burning at least into the ends of stock tangs the backing shoulders on receivers which are to be seated thereon sufiiciently to provide for the receiver seats of the required accuracy on the stocks. This prior method 332L792 Patented Mar. 20, 1973 involves bringing a receiver to heat in a furnace and placing a stock in a fixture, then removing the hot receiver from the furnace and placing it into the fixture in line with the stock therein, and finally driving the stock against the receiver for burn-in of at least the receiver seats on the stock. However, while this prior method is entirely satisfactory in accurately fitting stocks to receivers, the steps involved do not lend themselves to fitting stocks to receivers at even moderately high mass-production efficiency. Thus, While a number of receivers may be kept in the furnace at the proper heat to have them available for their fitting with stocks in quickest possible succession, their transfer from the furnace into the fixture with a hand tool is a tedious and potentially hazardous task in any event. Also, the cautious transfer of hot receivers from the furnace into the fixture will inevitably entail some cooling of the receivers before their burn-in on stocks, wherefore the receivers are in the furnace overheated for the purpose of compensating to some extent for the heat loss in their transfer to the fixture. However, due to uncontrollable and also variable factors involved in the cooling off of the receivers in their transfer to the fixture, it is apparently impossible to have the receivers, at the time of burn-in, at the exact required heat for adequate burn-in on the one hand, without excessive charring of the wood on the other hand, because for successful pursuance of the method the heat in the receivers at the time of burn-in is kept at a level at which excessive charring of the wood would be inevitable. It is for this reason, and because excessive charring of the wooden stocks on burn-in of the receivers is intolerable, that this prior method further involves the additional step of coating the stock portions to-be-burned with a char-retarding compound to control the charring action on burnin, and preferably also cooling the receivers immediately after burn-in to stop possible continued charring action on the stocks.

It is the primary object of the present invention to devise a burn-in type method of fitting gun stocks to receivers at very much higher efficiency, including fewer steps and lower cost, than can be achieved with the aforementioned prior method, with the fit obtained between the stocks and receivers being equally accurate as with the prior method.

It is another object of the present invention to devise a burn-in type method of fitting gun stocks to receivers, in which a cold receiver is placed in a fixture, then heat is applied, not to the entire receiver, but only to a localized portion thereof best suited for most effective heat-up of the tangs thereon, and in such manner that the tangs come up to heat, not only to a readily controlled level at which burn-in is entirely adequate for accurate seating fit of the stock on the receiver, yet charring of the wood is negligible and entirely tolerable, but also so rapidly that the non-heated remainder of the receiver remains absolutely cold, whereupon a tanged stock is driven into seating fit with the receiver in the fixture. When heat is thus applied to the receiver, the same is already held in the fixture in position for drive-on of a stock, and all that remains for burn-in is driving a stock into seating fit with the receiver the moment its tangs come up to heat of the controlled level, thereby easily accomplishing that adequate burn-in with no more than negligible charring of the wood for which the controlled heat level of the receiver is set. Further, the also featured localized heating of the receiver affords in the large cold remainder of the receiver a highly effective heat sink which draws heat from the receiver tangs and, hence, away from the wood after burn-in, sufficiently rapidly to avoid continuing charring of the wood, wherefore the stock and receiver may after burn-in, remain in their seating fit without requiring any external cooling of the receiver. Finally, the method neither requires, nor provides for, the application of any char-retarding agent to the wooden stock.

It is a further object of the present invention to devise a burn-in type method of fitting gun stocks to receivers in which the aforementioned local and rapid heating of a receiver to a readily controlled level is achieved by high frequency induction heating, and more particularly by induction-heating elements in preferred coil form. Thus, such induction-heating elements are easily so sized and shaped, and also located in such fixed position relative to the receiver-holding fixture, as to define on a receiver in the fixture a desired and rather sharply delineated area which will be heated on applying high-frequency current to these heating elements. Further, heating in this manner of the desired local area of a receiver in the fixture to the desired controlled level is achieved in a matter of seconds, and once a preferred heat time cycle for a receiver has been determined, it is easy, in the pursuance of the method, to hold all successive heat time cycles to the preferred time cycle with, or even without, automatic timer interruption of each cycle.

Another object of the present invention is to devise a burn-in type method of fitting gun stocks to receivers, of which the machined tangs on the stocks are, by preference, so oversized in part as to permit their partial interprojection with the tangs on receivers before heat-up of the latter, whereby a preferred method further provides for partial assembly so that extent of a stock and receiver, and then placement of the partially-assembled stock and receiver into the fixture for successive heat-up of the receiver and burn-in of the stock. Thus, by selecting, in the machining of the tangs on stocks, the longitudinal extent of their oversized portions, there is afforded a choice for burn-fitting the opposite sides of the tangs on a stock to the opposite sides of the tangs on a receiver either over a very small extent of their length or to any greater lengthwise extent, at any extent of which adequate seats for the receiver are burned in the stock. Further, in thus partially preassembling stocks and receivers, the stocks are with their tangs already partly interprojected with the tangs on the receivers before heat-up of the latter, so that the subsequent finish-drive of the stocks for burn-in by the receivers is timewise very brief and is also under effective guidance by the interprojected tangs. Of course, fitting stocks to receivers in accordance with this preferred method is made possible in the first place by heating the receivers with the aforementioned highfrequency induction elements which, while heating the receivers, will not heat any parts of wooden stocks within the heating field of these elements.

It is another object of the present invention to devise a burn-in type method of fitting gun stocks to receivers in which, in placing the aforementioned partially assembled receiver and stock into the fixture, the opposite sides of the receiver remain exposed, and the high-frequency induction heating elements are in the preferred form of opposite spaced coils which flank the placed receivers on its opposite sides over an area which includes, or is largely confined to, the end of the receiver from which the tangs projects. Thus, with the receiver being customarily of minimum thickness across its opposite sides, the flanking coils will rapidly and even bring the receiver up to burn-in heat throughout its affected local mass, including the end shoulders on the receiver and the tang formation therebeyond for their adequate burn into the stock into seating fit therewith on the finish-drive of the stock into the receiver. Further, in thus placing a partially assembled receiver and stock into the fixture, the very part of the receiver which, on being heated, would burn a grasping hand, is by the flanking coils sutficiently inaccessible to compel an attendant to remove a finished receiver and stock assembly from the fixture by safely grasping the far more readily accessible stock.

Further objects 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 for illustrative purposes:

FIG. 1 is a side view, partly in section, of a partially assembled receiver and stock;

FIG. 2 is a fragmentary bottom view of the partially assembled receiver and stock as seen in the direction of the arrow 2 in FIG. 1;

FIG. 3 is a side view, partly in section, of the same receiver and stock fully assembled;

FIG. 4 is a fragmentary section through the receiver and stock taken substantially on the line 4-4 of FIG. 3;

FIG. 5 is a fragmentary top view of apparatus for assembling the receiver and stock;

FIG. 6 is a fragmentary side view of the same apparatus as seen in the direction of the arrow 6 in FIG. 5; and

FIG. 7 is an enlarged section through a modified element of the apparatus.

Referring to the drawings, and more particularly to FIGS. 1 and 2 thereof, the reference numerals 10 and 12 designate a metal receiver and a wooden gun stock which have tangs 14 and 16, respectively. The receiver 10, being in this instance a steel forging, has a seating end 18 from which the spaced receiver tangs 14 extend, and the stock has a seating end 20 from which the stock tangs 16 extend. For a firm and secure mount of the receiver 10 on the stock 12, the receiver tangs 14 and stock tangs 16 are interprojected, and the ends 22 and 24 of the receiver and stock tangs 14 and 16 are to butt against the seating ends 20 and 18 of the stock 12 and receiver 10, respectively. customarily, the tangs 16 are machined on the stock 12 so as to be interprojectable with the receiver tangs 14 only partially at the most. In the present instance, the stock tangs 16 are machined so as to be readily interprojectable with the receiver tangs 14 to the partial extent shown in FIGS. 1 and 2, i.e., the stock tangs 16 are machined to fairly fit with the receiver tangs 14 over the extent of their ready interprojectability, but the stock tangs 16 are over an endlength 1 thereof oversized so as to interfere with full interprojection of the stock tangs with the receiver tangs (FIG. 2). Thus, the ends 24 of the stock tangs 16, which are to rest on the seating end 18 of the receiver, are in this instance oversized by being square and, hence, will not fit the radius formations 26 between the receiver seating end 18 and the therefrom extending tangs 14 (FIG. 2), and in this instance also projecting tongues 28 on the stock tang ends 24, which are to extend and fit in a recess 30 in the receiver, and are oversized by being left sufficiently thick to interfere with their entry into this recess 30.

The exemplary partially-interprojected receiver and stock are to be fully interprojected according to a featured method of the invention, which involves burning away the excess wood on the stock which interferes with full interprojection of the latter with the receiver to the extent of burning at least the seating end 18 of the receiver into uniform and accurate fit with the stock tang ends 24, while forcing the stock into full interprojection with the receiver. To this end, only a part of the receiver, including the surfaces thereof for burning away the excess wood on the stock, is subjected to high-frequency induction heating, with the subjected receiver part coming very quickly to wood-burning temperature, whereupon the stock is forced into full interprojection with the receiver to the extent of bringing the end tongues 28 on the stock tangs 16 into full register and burn-fit with the receiver recess 30, and burning the seating end 18 of the receiver into uniform and accurate fit with the stock tang ends 24.

The method is practiced in preferred and also featured apparatus 34 (FIGS. 4 and 5), which comprises a fixture 36 for removably holding a partially interprojected receiver and stock, a high-frequency induction heating unit 38, and a stock driving ram 40. The fixture 36 includes fixed brackets 42, 44, 46 and 48 on a table or other support 50, of which bracket 42 provides a rest surface 52 against which the receiver is to bear with its other end 54, and from which extends a dowel pin 56 which is to project into an aperture 58 in the receiver. Bracket 44 has a groove 60 of which the opposite side walls 62 and 63 straddle the receiver on its opposite side faces 64 and the lower side wall 63 serves as a bottom rest, and the bottom wall 66 of the groove serves as a back stop for the nearby side edge 68 of the receiver. The bracket or post 46 has an adjustable screw 70 of which the head 72 serves as a bottom rest for the stock, and the bracket 48 carries an adjustable screw 74 of which the head 76 serves as a back stop for the stock. Pivoted at 78 to the bracket 42 is a gate 80 having spaced lugs 32 which, in the closed full-line gate position, straddle the receiver. Thus, with the gate 80 in its open dotted-line position (FIG. 5), a partially interprojected receiver and stock 10, 12 may laterally be placed into a fixed position in the fixture 36, by passing the receiver into the groove 60 in bracket 44 and placing the stock onto the bottom rest 72, then shifting the receiver with its aperture 58 into the register with the dowel pin 56 and with its end 54 into butting engagement with the rest surface 54 on bracket 42, and finally thrusting the receiver and stock against the back stops 66 and 76. The partially interprojected receiver and stock are then accurately positioned in the fixture 36. Of course, lateral introduction or placement of a partially interprojected receiver and stock into the fixture in this or a similar manner is accomplished with hardly any skill and virtually instantaneously in a single-motion manipulation of the receiver and stock by an operator. With a receiver and stock thus placed in the fixture, the gate 80 may be closed for additional location of the receiver and stock.

The high-frequency induction heating unit 38 may be of any commercial available type, such as one manufactured by Lepel High Frequency Laboratories, Inc., in New York City, for example. The exemplary unit 38 has provisions for converting AC from a commercial power line to a high frequency suitable for induction heating, and this unit includes in this instance at least one pair of spaced load or heating coils 84 and 86 which are interconnected, and by leads 88 and 90 connected with the high-frequency current source in the unit 38. The interconnected coils 84 and 86 are usually made of copper tubing through which water or another suitable cooling medium is customarily circulated in operation of the coils. The heating coils 84 and 86 are spaced for unimpeded passage therebetween of a partially interprojected receiver and stock into and also from the fixture 36 (FIG. 6), and they are shaped and located to flank, and thereby bring within their heating field, only a predetermined part, including the seating end 18, of the positioned receiver (FIGS. 5 and 6). The unit 38 is in this instance connected with a commercial AC line L through leads 92 and 94 (FIG. 6).

The stock driving ram 40' is reciprocable to and from the end of the positioned stock 12 in the fixture 36', and is to this end movable in a guideway provided by gib plates 96 on the table 50. The ram 40 is normally urged into the retracted full-line position (FIG. 5) by a spring 98 which bears against a bottom lug 100 on the ram. Cooperating with the ram 40 is a piston 102 in a preferably doubleacting cylinder 104 on the table 50'. Thus, on admitting fluid under pressure to one end of cylinder 104 and simultaneously venting the other end, the piston 102 is in its retracted position (FIG. 5 in which the ram 40 is also in its retracted position. Conversely, on admitting fluid under pressure to the other cylinder end and simultaneously venting the one cylinder end, the piston 102 will advance from its retracted position and thereby move the ram 40 toward the stock 12. Admission of fluid under pressure to either cylinder end and simultaneously venting the other cylinder end is in this instance under control of a manual valve (not shown).

There is also provided a suitable control for the highfrequency induction heating unit 38, which includes, in this example, a switch 106 and a presettable timer 1110. Switch 106, which is provided in the lead 94, is an exemplary snap-type switch which is manually closed and is opened by a relay 112 when energized. Relay 112 is in a timer circuit, and opens switch 106 when this circuit is closed. The timer circuit comprises in this instance a lead 116 from one side of the power line L to the pointer p of the timer 110, an adjustable contact 0 on the timer, a lead 118, relay 112, and a lead 120 to the other side of the power line L. The graduations on the timer denote seconds, with the pointer 11 being shown aligned with the 0 second graduation, and the timer contact 0 being in this instance set in alignment with the 7 second graduation. The timer circuit is closed, and hence switch 106 opened by relay 112, when in operation of the timer 110* the clockwise moving pointer p engages the timer contact 0, With the pointer p there upon immediately returning to the 0 graduation to open the timer circuit. The operation of the timer 110 is further such that its pointer p will start its time-cycle motion from the 0 graduation the moment switch 106 is manually closed for applying AC from the line L to the unit 38 until switch 106 is opened on the explained momentary closure of the timer circuit. Thus, on each manual closure of the switch 106, the timecycle operation of the high-frequency induction heating unit 38, including coils 84 and 86, is an exemplary seven seconds.

In pursuance of the featured method, a partially interprojected receiver 10 and stock 12 are placed in the fixture 36 in explained manner, whereupon switch 106 is manually closed for a time-cycle performance, of exemplary sevensecond duration, of the high-frequency induction heating unit 38, including its coils 84 and 86. During this brief time cycle, the affected part of the receiver 10, including its seating end 18 and nearby part of its recess 30 (FIG. 2), comes quickly up to heat, and at the end of the time cycle is at adequate heat for burn-fitting the stock to the receiver. Thus, the moment the time cycle is concluded, the aforementioned valve is manipulated for immediate advance of the piston 102 and ram 40-, in the course of which the stock 12 is fully interprojected with the receiver 10 to the extent of burn-fitting the end tongues 28 on the stock tangs in the receiver recess 30 and fully burn-seating the stock tang ends 28 on the receiver seating end 18 (FIGS. 3 and 4). To insure an entirely uniform and accurate fit between the receiver seating end 18 and the stock tang ends 24, the burn of the former into the latter is preferably such that the receiver seating end 18 forms a distinct impression i in the stock tang ends 24 (FIG. 4), with the advance of the ram 40 being to this end preferably stopped in the dotted-line position (FIG. 5) by a suitable stop (not shown). The ram 40 may then immediately be spring-retracted on manipulation of the described valve for retraction of the piston 102, whereupon the fully interprojected receiver and stock are removed from the fixture 36, preferably and by far most conveniently by grasping the readily accessible and cold stock remote from the heating coils 84, 86 and the still hot receiver part therebetween.

While in the pursuance of the method just described, burn-in of the receiver on the stock is readily controlled to bring the receiver tang ends 22 into fair fit with the stock seating end 20 (FIG. 4) without heating these tang ends 22, it is also feasible to dispense with the mentioned ram stop and, instead, let the receiver tang ends 22 act as a stop for the advancing ram 40 when the stock seating end 20' comes to bear against, and hence is in good and sightly fit with, the receiver tang ends 22. The thus butting stock seating end 20 and receiver tang ends 22 (FIG. 4) afford entirely adequate bearing area to withstand the driving force of the ram 40 which is controlled by the controlled pressure of the operating fluid in the cylinder 104. Thus, in machining the tangs 16 and seating end 20 on stocks they may readily be kept within tolerances at which, on full interprojection, according to the method, of a receiver and stock to full butting engagement between stock seating end and receiver tang ends, the receiver seating end 18 is burn-fitted to the stock tang ends 24 to the same or similar extent as in FIG. 4.

In the pursuance of the method, it is also entirely feasible to apply the ram 40 with its driving force to the end of the stock during a time-cycle performance of the highfrequency induction heating coils 84 and 86, say two seconds before the end of the exemplary seven-second cycle. The ram 40 may thus be advanced to its dot-and-dash line position (FIG. 5) in which it is stopped from further advance by the stock 12 until the coil-affected receiver part has reached the required burn-in temperature, even before the end of the time cycle, whereupon the ram will immediately advance further and fully interproject the receiver and stock to the extent of burn-fitting the receiver seating end to the stock tang ends. In so doing, the ram functions fully to interproject the receiver and stock independently of, and even before, the set end of the time cycle, and also at minimum temperature of the heated receiver part at which adequate burn-in of the receiver on the stock will take place. Moreover, the independent advance motion of the ram 40 for full interprojection of the receiver and stock could, if desired, be utilized to activate a limit switch (not shown) in the line connection with the unit 38 for interruption of the time cycle.

In the pursuance of the method, several important advantages are secured. Thus, in subjecting only a localized mass of a receiver, including its burn-in surfaces, to highfrequency induction heating, the affected localized receiver mass will come up to burning heat with characteristic rapidity, i.e., in a matter of seconds, and the remaining large mass of the receiver remains entirely cold which, therefore, acts as a highly effective heat-sink rapidly to draw heat away from the heated receiver mass and, hence, away from the burn-fitted wood of the stock. Further, with the receiver and stock being already in position in the fixture for their full interprojection before heatup of the localized part of the receiver, heat-up of the latter may be stopped at the lowest temperature at which, on immediately following full interprojection of the receiver and stock, the former will become fully burn-fitted with the latter with only negligible charring of the thus fitted wood of the stock. In this connection, numerous receivers have thus been burn-fitted with complete accuracy to stocks at temperatures of the heated receiver parts of from 600 to 650 F., and the charring of the affected wood of the stocks was negligible and entirely tolerable and did not in the least mar the beautiful appearance of the finished stocks, neither did it in any way weaken the firm seat of the receiver on the stock and its ability safely to withstand recoil shock on firing the guns. Many of the receivers were thus locally heated to within the above range of from 600 to 650 F. during the aforementioned exemplary time cycle of seven seconds. Of course, receivers may be, and have been, locally heated above 650 F. and for more or somewhat less than seven seconds, and their burn-fit with stocks was entirely satisfactory. Generally, and for high etficiency of the operation, the heating cycle is preferably kept below ten seconds. Also, local heat-up of receivers is preferably not to exceed 700 F. to insure satisfactory burn-fit with stocks with only negligible and entirely tolerable charring of the affected wood of the stocks. It has been found that, in order to achieve this, the receivers should be heated anywhere from approximately 600 F. to 700 F. at the most, for at temperatures slightly above 700 F. the operation deteriorated quite rapidly. Also, such negligible charring of the affected wood of the stocks as takes place on burnfitting the receiver thereto, stops with the full interprojection of the receivers and stock, for the described heatsink effect of the extensive cold mass of the receivers prevents continued charring of the affected wood, wherefore fully interprojected and burn-fitted receivers and stocks need not be separated, neither need the receivers be artificially cooled, for the purpose of avoiding any continuing charring of the affected wood.

The high-frequency induction heating unit 38 includes, in this instance, a second pair of spaced heating coils and 132 which flank the fixture-held stock in the vicinity of the ends of the receiver tangs 14, and are designed to heat the latter, though to a lower temperature than the other heated receiver part, including its seating end 18, because of the large interference of the wooden stock between the coils 130, 132 and the metal receiver tangs within their heating field. The thus more moderately heated receiver tang ends lend themselves to a heat and pressure fit, but not burn-fit, with the stock seating end 20' on full interprojection of the receiver and stock.

Should it be desired to also burn-fit the receiver tang ends 22 to the stock seating end 20, the latter is provided with sufficient excess wood to that end, and the receiver tang ends 22 are brought more intensely into the heating field of the coils 130 and 132 by deforming the latter like or similarly as in FIG. 7. Thus, front lengths 134 and 136 of the coils 130 and 132, between which a receiver and stock are laterally placed into and removed from the fixture, are extended further forwardly to bring the exposed receiver tang end 22 therebetween more effectively within their heating field, while rear lengths 138 and 140 of the coils 130 and 132 are for the same purpose brought closer to the exposed adjacent receiver tang end 22.

While excess wood of the exemplary stock 12, which interferes with full interprojection of the stock and receiver, is confined to a relatively short endlength of the stock, it is, of course, fully within the purview of the present invention to provide stocks with excess wood over a larger endlength thereof to permit initial partial interprojection of such stocks with receivers to a lesser extent than in FIGS. 1 and 2 with the described method being as fully applicable for full interprojection and burn-fit of such stocks with receivers. It is also entirely feasible to apply the method, if desired, to fully interproject and burn-fit stocks with receivers, of which the excess or interference wood of the stocks extends over the entire length of the machined stock tangs so that initial interprojection of receivers and stocks is possible only to a slight extent, or not at all. In that case, a receiver in the fixture may locally be heated to the required burn-in temperature, whereupon in the absence of the ram 40 and cylinder 104, a stock may be driven onto the receiver in any suitable manner.

What is claimed is:

1. Apparatus for burn-seating a tanged receiver on an interprojected tanged gun stock, of which the receiver and stock have seating ends for the ends of the stock tangs and receiver tangs, respectively, and the receiver tangs and stock tangs extend from the seating ends of the receiver and stock, respectively, comprising high-frequency induction heating means, including spaced heating coils; a fixture for lateral passage thereinto and therefrom between said coils of the partially interprojected and fully interprojected receiver and stock, respectively, with the partially interprojected receiver and stock held in the fixture in position in which only a part of the receiver, including its seating end, is flanked by, and Within the heating field of, said coils, with the coils being spaced to admit the tanged stock into full interprojection with the tanged receiver for burn-seating its seating end on the stock tang ends; control means for connecting said heating means with, and disconnecting it from, a current source; and a ram operable to thrust the fixture-held stock into full interprojection with the fixture-held receiver.

2. Apparatus as in claim 1, in which said heating means include another pair of spaced heating coils between which the partially interprojected and fully interprojected receiver and stock is laterally passed into and from said fixture, respectively, and the receiver tang ends of the positioned partially-interprojected receiver and stock in said fixture being flanked by, and within the heating field of, said other pair of coils, so that on heat-up of the receiver and operation of said ram the seating end and tang ends of the receiver are burn-seated on the tang ends and seating ends of the stock.

3. Apparatus as in claim 1, in which said control means include a manual switch closable to connect said heating means with said current source, and timer means disconnecting said heating means from said current source a given time period from closure of said switch.

10 4. Apparatus as in claim 3, in which said timer means is presettable to vary said time period.

References Cited UNITED STATES PATENTS JOSEPH v. TRUHE, Primary Examiner B. A. REYNOLDS, Assistant Examiner US. Cl. X.R. 219 10.73, 10.79

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