Abstract:
A bolt action for a firearm which comprises a bolt with a removable handle which can be attached to the bolt for left handed use or for right handed use. The receiver has slots for back and forth movement and rotation to left or to right to close the chamber and has apertures for safe cartridge ejection either to the left or to the right according to the position of the handle. Primary cartridge extraction is provided for both in left handed and right handed use by a cam surface of equilateral triangular shape on the receiver and a co-acting shape on a neck of the handle as well as protection against erroneous movement of the handle to the wrong side, in use.

Description:
FIELD OF THE INVENTION 
     This invention lies in the field of bolt action firearms. In particular the invention relates to the bolt action of rifles as epitomised, for example, by the Mauser bolt action. The bolt action consists of a bolt moving back and forth in a receiver and held in the position in which it shuts the chamber by locking its handle or lugs against an abutment in the receiver with a quarter turn of the bolt. 
     BACKGROUND OF THE INVENTION 
     The Inventor is aware that presently most bolt action rifles are made for right handed users, i.e. the right hand is used for operating the bolt, the face and body are to the left of the rifle and spent cartridges are ejected to the right There are, however, some bolt action rifles made exclusively for left handed users, i.e. the left hand is used for operating the bolt, the face and body are to the right and spent cartridges are ejected to the left. 
     It is a recognised problem in the art that when a left handed user uses a right hand bolt operation rifle (or less commonly a right handed user uses a left hand bolt operation rifle), the use is awkward and there is a risk of injury to the user. This is due to a tendency for the user to place the face and body on the side to which spent cartridges are ejected from the rifle. 
     A large number of existing bolt action rifles are based on the Mauser K98 action which consists of a bolt with a handle which is an integral part of the bolt, on the right hand side to be operated normally with the right hand and a receiver within which the bolt is axially displaceable. With the bolt in the firing position, the bolt handle is down to the right of the action and two or more lugs on the bolt locate into recesses inside the receiver holding the chamber closed with the cartridge inside. 
     To eject a spent cartridge and load a new round the bolt handle is lifted upwards rotating the bolt anti-clockwise through 90 degrees. During this rotation a part of the bolt or bolt handle engages an angled surface or cam surface on the receiver forcing the bolt rearwards. This is known as the primary extraction which is very important as the leverage obtained against the cam surface is designed to release cartridge cases that may get stuck after firing due to dirt or over pressure etc. Once the bolt reaches the full 90 degree travel the lugs inside the receiver are freed from the recesses and located in slots which allow the bolt to be pulled to the rear of the action. The rearward movement of the bolt brings with it the cartridge case the rim of which is gripped by the extractor at the front of the bolt. As the bolt approaches its complete rearward travel the cartridge case is ejected out of the right hand side of the action by means of an ejector which is a sprung component either set in the head of the bolt or in the side of the action. 
     Generally when a left handed rifle is required the whole action and bolt has to be built the opposite way around or mirror reversed, allowing the left handed person to be able to operate the weapon with his left hand rotating the bolt clockwise to open the bolt. 
     Such left handed bolt actions are few and far between and tend to be extremely expensive as not many manufacturers make them and those that do in small quantities. More often than not when a left handed person requires a rifle he is obliged to settle for a normal right handed action fitted with a left handed stock. 
     SUMMARY OF THE INVENTION 
     A solution of these problems according to the invention is to provide a bolt action for a firearm which is configured to be interchangeably useable by left handed and right handed users. 
     The bolt action includes a receiver, a bolt axially displaceable within the receiver, a bolt handle for the bolt, formations for locking the bolt in a position in which it doses the chamber of the firearm, extractor and elector means in the action, a firing pin in the bolt, characterised in that the receiver and/or bolt have/has cam surfaces oriented for primary extraction both by clockwise and anti-clockwise rotation of the bolt, the receiver has apertures for spent cartridge ejection to both left and right hand sides of the firearm and the handle is oriented relative to the bolt for configuration either to the left hand or right hand of the bolt. 
     The bore of the receiver may include a guide slot or slots and the bolt a co-acting lugs or lugs. The guide slot(s) extend(s) longitudinally along the bore of the receiver for movement of the bolt back and forth and circumferentially both clockwise and anti-clockwise in the bore for locking the action by e.g. a quarter turn. If there are two slots they must be in two angularly separated positions, similarly if there are two lugs. There may be both two slots and two lugs. There may be two (or more) axially separated sets of lug(s) and slot(s), to provide better assurance against failure of the lug(s) due to overpressure, etc. 
     The receiver may have a circumferential slot for a co-acting lug or lugs on the bolt handle or a co-acting neck of the handle located adjacent the bolt in use. 
     These arrangements permit the bolt handle to be oriented relative to the bolt so that the bolt can be used to rotate the bolt to the left or to the right, as desired, for left hand or right hand axial displacement of the bolt. 
     The bolt handle may be oriented relative to the bolt by being removable from the bolt for reattachment in the desired left hand or right hand configuration. This reattachment may be by insertion into the same hole in the bolt with the handle rotated either to left or to right i.e. by one hundred and eighty degrees. In a preferred embodiment there are two holes in the bolt for insertion of the handle into one for right hand use and into the other for left hand use. These two holes in the bolt may be one hundred and eighty degrees angularly separated from each other. The holes may be given a non-symmetrical shape to ensure that the handle is correctly inserted in each case. Other formations than holes may be provided for attaching the handle to the bolt. 
     An alternative arrangement may be for the handle to remain attached to the bolt but be rotated in its attachment to a position for left hand use or to a position for right hand use. 
     The cam surfaces may be provided either on the receiver, in the slots in the bore of the receiver, on the bolt, on the lugs on the bolt or on the handle, with a follower on a co-acting part, or a cam surface on both co-acting parts. In a preferred embodiment the cam surfaces are provided on the receiver, positioned to act against the handle when it is attached to the bolt in either the left hand or right hand configuration. Preferably the handle has cam surfaces that act as followers of or co-act with the cam surfaces of the receiver. 
     The cam surfaces on the receiver may be in the form a triangular projection having an apex directed towards the rear. The triangular projection may be in the form of an equilateral triangle. 
     The cam surfaces may include one or more arcuate zone, for example, in the form of a pair of parabolic or hyperbolic curves meeting at an apex directed towards the rear. 
     The bolt handle may include a neck adjacent the bolt provided with a cam following surface. This surface may be configured complimentarily to the cam surface. 
     The guide slot(s) and/or lugs and/or the handle preferably have a stop member provided in a central zone of said slot(s) and/or lug(s) or other means adapted to reduce the risk of the bolt handle being rotated between the left hand and right hand configurations when this is not desired. Such undesired rotation can result in jamming or other adverse or dangerous consequence. 
     In one embodiment, the cam following surface of the neck of the handle is a polygon having a corner directed towards and offset from the apex of the cam surface, to reduce the risk of the bolt handle crossing over between the left hand and right hand configuration when this is not desired. 
     The stop member may be in the form of a cam surface or surfaces, e.g a cam surface on the receiver directed towards the rear such that when the bolt handle or a formation on the bolt engages It the bolt is rotationally displaced as it moves towards the rear, primary extraction of a cartridge in the receiver takes place and over-turning of the bolt is inhibited. 
     The receiver may include a pair of opposed laterally directed apertures for ejection of a cartridge from the receiver either to the right or to the left of a user, as desired, for left hand or right hand use of the bolt, respectively. 
     The bolt is preferably provided with cartridge extractor and ejector means at the opposite end of the bolt from the bolt handle, the extractor means being displaceable in sympathy with the bolt in conventional manner. 
     The receiver may include a channel in which a flange of a firing pin is located and which inhibits the firing pin from rotating as the flange is trapped within this channel. The bolt may have at its rear a chamfer which when the bolt is rotated to free it from the position in which it closes the chamber, after a shot, the rotation causes the firing pin flange to ride up this chamfer effectively pulling the firing pin rearward to cock it. This chamfer is symmetrical so that whether the bolt is rotated clockwise or anti-clockwise the firing pin will ride up this chamfer to cock the firing pin, thereby providing for left hand or right hand configuration. The sear of the firing mechanism is also located in the channel so that when the bolt is returned to close the chamber with a new round in it for the next shot, the firing pin flange engages the sear, to retain the firing pin in the cocked condition, to be released when the trigger is pulled. 
     The chamfer may be in the form of two chamfered portions extending from a common source, mirror-image fashion. 
     According to a second aspect of the invention, there is provided a receiver for a bolt action weapon, the receiver including a circumferential guide slot in the bore of the receiver for lugs on the bolt and/or for a bolt handle, which guide slot extends along a portion of the circumference of the receiver both to the left and to the right of a plane intersecting the longitudinal axis of the receiver, thereby permitting the bolt handle to be displaced along the guide slot to rotate the bolt to the left and to the right, as desired, for left hand or right hand axial displacement of the bolt. 
     The guide slot may have a bolt handle stop member provided in a central zone of said slot, thereby reducing the risk of the bolt handle crossing over between the left hand and right hand configuration when this is not desired. 
     The stop member may be in the form of a cam surface directed towards the rear of the receiver such that when the bolt handle engages and is displaced along the cam surface, primary extraction of a cartridge in the receiver takes place. 
     The cam surface may be in the form a triangular projection having a apex directed towards the rear. The triangular projection may be in the form of any acute angled triangle, typically an equilateral or a right angled triangle. 
     The cam surface may include one or more arcuate zone(s), for example, in the form of a pair of parabolic or hyperbolic curves meeting at an apex directed towards the rear. 
     The receiver may include a pair of opposed laterally directed apertures for ejection of a cartridge from the receiver either to the left or to the right of a user away from the user, as desired. 
     According to a third aspect of the invention there is provided a bolt for a bolt action weapon, the bolt including a bolt handle which is displaceable relative to the bolt for configuration of the weapon to permit either left hand or right hand axial displacement of the bolt. 
     The bolt handle may be removable from the bolt for reattachment in the desired left hand or right hand configuration. 
     The bolt handle may include a neck portion directed towards the bolt and being provided with a cam engaging surface. 
     The cam engaging surface may be configured complimentary to a cam surface of the weapon. 
     In one embodiment, the cam engaging surface of the neck portion is a polygon having a corner directed towards and offset from the apex of the cam surface, thereby reducing the risk of the bolt handle crossing over between the left hand and right hand configuration when this is not desired. 
     The bolt is configured such that when the bolt is displaced and rotated to the right, a cartridge is ejected to the right away from the user, and vice versa. 
     The bolt may be provided with a cartridge extractor portion at the bolt handle remote end of the bolt, the extractor being displaceable in sympathy with the bolt. 
     According to a further aspect of the invention there is provided a bolt action firearm convertible, e.g. in the field, from left handed configuration to tight handed configuration, said weapon including at least one of the action, the receiver, and the bolt, substantially as described above. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The invention will now be described, by way of non-limiting example only, with reference to the accompanying drawings. 
     In the drawings, 
     FIG. 1 shows, in plan view, the action in accordance with the invention in a left hand user configuration; 
     FIG. 2 shows, in plan view, the action shown in FIG. 1 in a right hand user configuration; 
     FIG. 3 shows, in plan view on a section X—X (see FIG.  4 ), the receiver of the action shown in FIG. 1; 
     FIG. 4 shows, in a side view from the left, the action shown in FIG. 1; 
     FIG. 5 shows, in a side view from the left, the bolt of the action shown in FIG. 1, (FIG. 5A shows the handle which fits the bolt); and 
     FIG. 6 shows, in underneath view, the bolt of the action shown in FIG. 1 (with an end view  6 A). 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the Figures, reference numeral  10  generally indicates a bolt action for a firearm in accordance with a preferred embodiment of this invention. 
     The action  10  is similar to the normal two lug bolt action design, like the Mauser K98. The action  10  includes a receiver  12 , a bolt  14  axially displaceable within the receiver, a bolt handle  16  for the bolt, formations for locking the bolt in a position in which it closes the chamber of the firearm comprising lugs pairs  11  and  13  on the bolt and circumferential grooves  31  and  33  in the bore of the receiver. Longitudinal grooves  34  and  35  in the bore of the receiver allow the bolt to be axially displaced within the receiver. Extractor means  17  and ejector means  18  are on the end  20  of the bolt and a firing pin  15  is located in the bolt. The action differs in that the receiver has a cam surface  22  for primary extraction both by clockwise and anti-clockwise rotation of the bolt. The cam surface is a symmetrical having a triangular shape and an apex  23 . The receiver of the action has two apertures for ejection of spent cartridges on the left  19  and on the right  21 . The bolt and the bolt handle are separate components, and the handle can be removed from one side of the bolt  14  and placed in the bolt  14  from the opposite side (see FIGS.  1  and  2 ). The handle has a forked part  28  which can be inserted either into a hole  32  in the bolt from the left or in a hole  33  in the bolt from the right. The holes  32  and  33  are separated by an angle of one hundred and eighty degrees on the bolt. Both holes are asymmetrical so that in both cases the handle can only be put in the correct way. In this example, the firing pin assembly must be pulled out of the bolt to insert or remove the handle and when the pin assembly is inserted it engages formations  33  and holds the handle so that it can not be removed from the bolt. 
     The firing pin assembly (the rear end  15  is seen in FIGS. 1 and 2) operates through the center of the bolt. The bolt has an extractor  17  and ejector  18  at the bolt head  20  (see FIGS.  6  and  6 A). 
     The bolt with the bolt handle on the left hand side (FIG. 1) and on the right right hand side (FIG. 2) work the same way except that the former requires the handle and bolt to be rotated clockwise a quarter turn to unlock it from the left handed position shown in FIG.  1  and rotated anti-clockwise a quarter turn to unlock it from the right handed position shown in FIG.  2 . The neck of the handle has a cam or follower surface  24  with an apex  25 . In both cases when the cam surface of the handle engages the cam surface of the receiver primary extraction of the cartridge occurs before the rotation of the bolt reaches the full 90 degrees. Chamfers  27  and  29  on the lug pairs  11  and  13  permit this cam action. On reaching the full 90 degrees the user pulls the bolt to the rear, the lugs sliding in the longitudinal grooves in the receiver bore, and this will eject a cartridge case (not shown) when it approaches the end of its travel. The cartridge case will eject to the left in FIG. 1 (left handed use) and to the right in FIG. 2 (right handed use). 
     If the bolt  14  is now pushed forward to put a new cartridge in the chamber the cam surface of the neck of the handle passes the apex of the cam surface on the receiver before the bolt  14  is able to turn. (The lugs on the bolt are still in the longitudinal grooves inside the receiver). The cam surface on the handle then makes contact with the same side of the triangular shape of the cam surfaces on the receiver as the handle, which forces the bolt clockwise if the handle is to the right or anti-clockwise if the handle is to the left. At this stage the lugs on the bolt have reached the circumferential cavities inside the receiver  12 . By further movement the bolt handle  16  is forced downwards and when it reaches the end of the rotation to the full 90 degrees the lugs are locked inside the circumferential grooves in the bore of the receiver. 
     When the bolt is in the closed position the extractor and ejector in the head of the bolt are on a vertical axis, with handle on the right the extractor is at the bottom and with the handle at the left the extractor is at the top. 
     Therefore with the handle on the right hand, when the bolt is rotated 90 degrees anti-clockwise to unlock the bolt, the extractor  18  is also rotated through 90 degrees anti-clockwise in sympathy with the bolt and will be located on the right hand side of the bolt and ejector on the left which ejects the cartridge case out the right hand side of the action. 
     With the handle on the left side the bolt is rotated clockwise and the cartridge is ejected to the left. 
     The firing pin has a flange which runs in a groove  37  in the bore of the receiver which keeps the pin from rotating but allows it to be moved back to cock the pin and move forward to fire a round. The flange is engaged by the sear  36  of the release mechanism of the trigger  38  when cocked. When the bolt is in the position closing the chamber (either left-handed or right-handed) there is a recess  39  at the rear of the bolt which clears space for the flange on the firing pin which allows the firing pin to reach the cartridge when the firing pin is released by the trigger mechanism. 
     On both sides of the recess  39  in the rear of the bolt there are chamfers  40  and  41  which when the bolt is rotated clockwise or anti-clockwise causes the firing pin to ride up one or the other of these chamfers pulling the firing pin rearward away from the sear. This disables the firing pin ensuring that it can not accidentally discharge a round. 
     The angled section on the triangular cam surface  22  and the angled section  24  on the bolt handle ensure that the bolt can only be rotated clockwise to close and lock, when in a right hand user configuration, or anti-clockwise in a left hand user configuration. 
     When the bolt handle is removed and placed into the same aperture on the opposite side for left handed operation, it would mean that the bolt is in fact rotated 180 degrees before it can be inserted into the bolt. When the bolt is inserted into the receiver and pushed closed the angle on the opposite side of the bolt handle will pass the apex  25  and will make contact with the left hand side of the triangular cam surface on the receiver, thereby ensuring that the bolt can only be rotated anti-clockwise to lock. 
     As the bolt has been rotated 180 degrees the extractor is now sitting on the left hand side and will therefore eject the cartridge case on the left side when drawn to the rear. However, when pushing the bolt forward and closing it the bolt now rotates 90 degrees anti-clockwise therefore turning the extractor to the bottom position the same as when the handle was on the opposite side of the bolt. Also the recess at the rear of the bolt which allows the firing pin to travel forward to fire the weapon is once again in the right position. As this bolt is now rotated the opposite way to open it has also been machined with the chamfer on the right of this gap on the bolt which will force the firing pin sear to ride up the chamfer when rotating and so pulling the firing pin away from the front of the bolt. 
     This invention therefore allows one to change the rifle from being right handed to left handed simply by removing the bolt handle from the right hand side of the bolt and fitting it into the left hand side of the bolt. 
     The bolt handle interlocks with the firing pin assembly holding it in place and the firing pin spring forces a sleeve around the firing pin into a recess  42  in the bolt handle to hold it in place and to prevent it from coming out of the bolt body. 
     To remove the bolt handle the firing pin sleeve which sticks out at the rear of the bolt has to be depressed a small amount and the bolt handle can then easily be removed and put into the same aperture from the opposite side where when fully in position it will again be held in place by the firing pin sleeve and spring. 
     List of numerals used in drawings: 
       10  bolt action 
       11  lug pairs on bolt 
       12  receiver 
       13  lug pairs on bolt 
       14  bolt 
       15  firing pin rear end 
       16  bolt handle 
       17  extractor 
       18  ejector 
       19  left aperture 
       20  bolt head 
       21  right aperture 
       22  cam surface on receiver 
       23  apex of cam surface on receiver 
       24  cam surface on bolt handle 
       25  apex of cam surface on handle 
       26  central zone of receiver 
       27  chamfers on lugs 
       28  forked part of handle 
       29  chamfers on lugs 
       30  hole in bolt for firing pin 
       31  circumferential slots in bore of receiver 
       32  left hand hole in bolt for handle 
       33  right hand hole in the bolt for handle 
       34  longitudinal slot in receiver bore 
       35  longitudinal slot in receiver bore 
       36  sear 
       37  groove for firing pin flange 
       38  trigger 
       39  recess at rear of bolt 
       40  chamfer to left of recess at bolt rear 
       41  chamfer to right of recess at bolt rear 
       42  locking formation in forked part of handle