Rifle with interchangeable barrel

Rifle with interchangeable barrel having an interchangeable barrel formed by attachment of a barrel to a receiving block which has locking lugs and is provided with alignment structure for aligning the interchangeable barrel with other components of the rifle and having a threaded passageway to receive a screw such that the interchangeable barrel may be easily removed and replaced.

TECHNICAL FIELD OF THE INVENTION 
The present invention relates to fire arms, and in particular, rifles 
having interchangeable barrels. 
BACKGROUND OF THE INVENTION 
In the past there have been a number of attempts to produce various types 
of firearms with interchangeable barrels. Most of this effort has been 
concentrated on shotguns designed to accommodate different barrels. Some 
of these attempts are shown in U.S. Pat. Nos. 4,989,359 and 2,529,733. 
However, with shotguns, being area-fire weapons, there was not great 
concern about small variations in fit of the barrel which effect accuracy. 
Also, there have been attempts to place interchangeable barrels on 
pistols, together with interchangeable cylinders, as shown in U.S. Pat. 
No. 4,297,801. 
An attempt to provide a rifle with interchangeable barrels is shown in U.S. 
Pat. No. 3,611,611, which requires the use of a concentric sleeve over the 
barrel to provide a rifle with an interchangeable barrel. This system 
suffers the disadvantages that it is complex and there is the possibility 
for slack between the rifle barrel and the sleeve, which can affect 
accuracy each time a barrel is removed and replaced. 
There has been a continuing need to provide a rifle with interchangeable 
barrels which are both easily and quickly changed while maintaining 
accuracy of the weapon. The present invention provides a rifle with 
interchangeable barrels which conserves cost, allows the shooter to use 
one stock with which he is familiar and comfortable, and provides 
comparable weight and balance to the total firearm even when the different 
barrels are attached. All these factors are believed to be helpful to 
maintaining accuracy by allowing the shooter to maintain the same feel and 
touch, even though different caliber barrels are utilized. A major 
shortcoming of prior attempts to provide an interchangeable barrel for a 
rifle has been to achieve alignment of the barrel and sight system to 
maintain accuracy. Thus, interchangeable barrels have been successful in 
shotguns because minor variations in accuracy do not have much effect with 
these area-fire weapons. Interchangeable barrels or barrel inserts have 
found some use with pistols, but again in uses where accuracy is not a 
paramount concern. There has not been a successful large bore hunting 
rifle which uses interchangeable barrels. It is believed that this is 
directly attributable to difficulties with zeroing the weapon each time 
the barrel is changed. The present invention now permits use of 
interchangeable barrels for rifles which do not require rezeroing the 
weapon each time the barrel is changed. 
Thus, the present invention satisfies a long-felt need and offers 
substantial advantages to the shooter. These advantages include being able 
to use the same stock assembly trigger housing and bolt guide 
configuration for the different barrels. Thus, the shooter continues to 
utilize the basic components with which he is familiar and comfortable. 
When the weapon is shouldered, it will come to his accustomed shooting 
position, unlike using separate rifles of the desired caliber where 
variations in stock length, shape and thickness require an adjustment for 
each different rifle. Also, the shooter has the advantage of being 
familiar with the same trigger pull and bolt action, thus further 
enhancing consistent habits which improve marksmanship. The rifle of the 
present invention also has the advantage that for a single stock assembly, 
a number of different rifle calibers may be used, thus allowing a hunter 
to take one stock and several barrels in a convenient-sized case for air 
travel to hunt large game and small game on one trip without the need to 
carry two or three different complete firearms in bulky containers such as 
long rifle cases which are frequently over four feet in length. The rifle 
of the present invention also offers the advantage that the system and 
mechanism for achieving the interchangeability of the barrels, each with 
its own sight system, allows the consistent return to zero each time the 
barrel is removed and replaced. Thus, the shooter only needs to zero the 
barrel initially. After that, the mounting mechanism allows the barrel to 
be removed and replaced without the need to rezero the rifle when barrels 
are changed. Thus, for example, when the hunter is on a trip in the 
wilderness, he may change barrels without the need to rezero the barrel. 
Without this feature, interchangeable barrels are not practical for the 
hunter, as many times he does not have the facilities, targets and other 
equipment necessary to accurately rezero the barrel while in the field. 
SUMMARY OF THE INVENTION 
The present invention relates to a rifle with interchangeable barrels. The 
interchangeable barrel of the present invention can be used on rifles 
which may be bolt action, semi-automatic or automatic. In one aspect, the 
invention provides for a receiving block which is easily interchangeable 
with other components of the rifle to provide for a quick change of the 
receiver block and its attached barrel such that it will align identically 
each time it is replaced. The receiver block forms a passageway with first 
and second ends. The first end of the passageway is threaded to receive a 
barrel of desired caliber. The second end of the passageway has locking 
lugs extending into the passageway for engagement of locking lugs on a 
rifle bolt. The receiver block also has an alignment structure for 
positioning the receiver block such that the vertical surfaces of the 
rifle bolt locking lugs and the receiver locking lugs will fit tightly 
together when the receiver block is mounted in place. The receiver block 
can also be provided with structure to provide alignment such that the 
axis of the receiver block will align with the axis of the rifle bolt 
travel to form a substantially single axis. 
In another aspect, the invention relates to a receiver block as described 
above together with a barrel affixed to the receiver block. Yet another 
aspect of the present invention relates to an interchangeable barrel 
comprised of a barrel affixed to a receiver block of the present invention 
and having a sight mounted thereon. 
Another aspect of the present invention relates to a rifle assembly with 
interchangeable barrel wherein a rifle bolt guide assembly is provided 
having a mounting member attached thereto for removably mounting a 
receiver block and barrel thereto. The mounting member has an alignment 
structure to provide for alignment along the axis of the firearm of the 
receiver locking lugs with the bolt locking lugs such that they mate 
together and also to align the axis of the receiver and barrel with the 
axis of the bolt travel such that they form substantially a single axis.

DETAILED DESCRIPTION 
FIG. 1 shows a preferred embodiment of the present invention. The 
interchangeable barrel of the present invention may be used with any type 
of rifle such as bolt action, semi-automatic or automatic. While the 
invention is described and illustrated with relation to a bolt action 
rifle, the invention may be applied to any type of rifle. In FIG. 1, there 
is a receiver block 10 which defines a passageway therethrough along axis 
A--A. Passageway 12 has a first end 14 and a second end 16. First end 14 
is adapted to be connected to a barrel of desired caliber, such as by use 
of threaded surfaces on the inside of the passageway 12. At the second end 
of the passageway are locking lugs (not shown in FIG. 1) protruding from 
receiver block 10 partially into passageway 12. These locking lugs are 
dimensioned to cooperate with corresponding locking lugs 18 on bolt 20. 
Any desired number of locking lugs and locking lug configurations may be 
used, but at least one locking lug is used. Preferably, two or more 
locking lugs are used on rifle bolt 20 with two or more corresponding 
locking lugs on receiver block 10. Receiver block 10 has alignment member 
22 downwardly extending therefrom. Alignment member 22 may be of any 
desired shape which serves to mount the receiver block 10 in bolt guide 
assembly 26 and align the receiver block 10 in operative relationship with 
bolt 20 along axis A--A such that locking lugs 18 of the bolt 20 will 
engage locking lugs in the receiver block 10. This happens when the 
locking lugs cam together to lock the bolt in position for firing. 
Alignment member 22 may also serve to align receiver block 10 such that 
axis A--A of receiver block 10 corresponds and aligns with bolt axis B--B. 
Axes A--A and B--B are aligned to form a substantially single axis C--C of 
the assembled rifle. Preferably, alignment member 22 is provided with a 
passageway 24, shown in phantom, for receiving a threaded screw to attach 
receiver block 10 to bolt guide assembly 26. The alignment of receiver 
block 10 and bolt 20 must be such that axes A--A and B--B meet to form a 
substantially single axis C--C (called the rifle axis herein) and that 
both be held in the proper operative position along the axis. Bolt guide 
assembly 26 is mounted on stock 28, shown in phantom. The rifle axis is 
that common axis extending through the barrel, the receiver and the bolt 
of the assembled rifle. 
Bolt guide assembly 26 has a wall 30 defining a passageway 27 to guide the 
bolt 20 along its axis B--B. Bolt guide assembly 26 has a first end 32 and 
protruding mounting member 34 for mounting of receiver block 10 to the 
bolt guide assembly 26. Protruding member 34 defines a channel 36 for 
receiving alignment member 22 of receiver block 10. Protruding member 34 
also contains passageway 38 positioned such that it will be aligned with 
passageway 24 of receiver block 10. The stock may be configured such that 
a passageway 40 is provided in the stock to align with passageway 38 of 
bolt guide assembly 26, thereby allowing a threaded bolt or screw to be 
passed through it. Alternatively, the stock may be made so that it ends 
before passageway 38. Receiver block 10 is attached to protruding member 
34 by inserting alignment member 22 into channel 36. A threaded bolt or 
screw can be passed through passageway 38 and engage threads in passageway 
24, permitting receiver block 10 to be firmly held against protruding 
member 34. 
Between the bottom of depending member 22 and the bottom of channel 36 
there should be a small space provided when the two parts are drawn 
together. This prevents small grains of sand or dirt from interfering with 
the fit of rifle bolt 20 and receiver block 10. A space of about 0.01 
inches or greater is sufficient for the purpose. Very close tolerances 
should be maintained between the rear of depending member 22 and the rear 
wall of channel 36 (rear indicating the direction away from the muzzle of 
the barrel). Preferably, the tolerance is about 0.002 inches or less. This 
will ensure that recoil forces are transferred from the depending member 
of the receiver block to bolt guide assembly 26, thereby sparing strain on 
the threaded bolts or other attaching mechanism utilized. Further, it is 
advisable to shape the parts so as to create void spaces adjacent to 
surfaces 42 and 47 when the receiver block and mounting member are drawn 
together such that dirt and small grains of sand or other particulate 
matter will not interfere with the flush fit of the mating surfaces 42 and 
47. In a preferred embodiment, the attachment structure 22 is positioned 
midway along the receiver block and midway between pairs of alignment 
surfaces 42. While the attachment structure may be positioned behind or in 
front of the mating surface(s), that position is less desirable because as 
the two parts are drawn together, torque may be applied such that 
alignment of the rifle components is compromised. 
Preferably, a second alignment structure is also provided in the form of 
one or more alignment surfaces 42 dimensioned to mate against 
corresponding alignment surfaces on protruding member 34 (shown in phantom 
in FIG. 1). Alignment surfaces 42 and corresponding alignment surfaces on 
protruding member 34 serve to align axis A--A with axis B--B such that 
they form substantially one axis (the rifle axis), thus permitting axial 
engagement of locking lugs 18 with locking lugs in receiver block 10. 
FIG. 2a is an enlarged view of the receiver block of FIG. 1. Like numbers 
refer to like elements. FIG. 2b is an end view from first end 14 of 
receiver block 10. From this view, one may see the receiver block locking 
lugs 44 which have a flat surface 45 which is perpendicular to axis A--A 
of the receiver block, and an angled surface 46 which is at an angle to 
the axis A--A of the receiver block to provide a camming action when 
engaging the locking lugs 18. FIG. 2c shows an end view of the receiver 
block 10 from the second end 16 of the receiver block. Like numbers refer 
to like elements. FIG. 2d is a bottom view of receiver block 10, and 
again, like numbers refer to like elements. 
FIG. 3 is a partial frontal view of FIG. 1 and like numbers are used to 
refer to like elements. Alignment surfaces 42 on receiver block 10 are in 
a plane at an angle to a perpendicular plane passing through the rifle 
action when held in the normal firing position. Also, locking lugs 44 of 
receiver block 10 can be seen. (For purposes of clarity, the barrel is not 
shown in either FIGS. 1, 2 or 3.) Alignment surfaces 42 mate with 
alignment surfaces 47 of protruding member 34. In a preferred embodiment, 
alignment surfaces 42 form a dovetail or partial "V" shape and extend 
generally parallel to axis A--A. In a preferred embodiment, the alignment 
surfaces 42 are in planes parallel to axis A--A. It is not necessary that 
the mating surfaces be in planes parallel to axis A--A. For example, the 
alignment surfaces may be in planes at acute angles to the axis A--A. As 
shown, all of surfaces 42 need not be in the same plane. Alignment 
surfaces 47 are in planes corresponding to mating alignment surfaces 42 on 
the receiver block. As shown, one or more alignment surfaces may be used, 
and they can be in more than one plane. The alignment member 22 transfers 
recoil directly to bolt guide assembly 26 when the firearm is discharged. 
This prevents undue stress on the threaded screw attaching receiver block 
10 to mounting member 34 which otherwise might damage or harm the threaded 
bolt. The force of recoil is transferred from the rear surface of 
depending member 22 to the rear wall of channel 36. FIG. 2e is a 
cross-sectional view of the receiver block. Alignment surfaces 42 and 47 
are illustrated as flat surfaces. They are dimensioned such that they will 
mate with one another when receiver block 10 is positioned over protruding 
member 34 and tightened into position. While the surfaces are shown as 
flat surfaces, they may be of any desired configuration. 
FIG. 4 shows a cross-sectional area of a receiver block 10 and a barrel 50. 
Like numbers in FIG. 4 refer to like elements in FIGS. 1, 2 and 3. Desired 
barrels are combined with a receiver block to form a unified barrel and 
receiver block combination referred to herein as an interchangeable barrel 
51. Once the barrel 50 is screwed in receiver block 10 and head space 
adjusted, the barrel 50 and receiver block 51 will remain as a single 
interchangeable barrel unit. Thus, a number of receiver blocks combined 
with different barrels give the shooter the ability to change barrels when 
desired. Standard barrels which can be used include 30.06, 308, 270, 243, 
25.06, 6 mm, 22/250, and 280. Additionally, magnum barrels can be 
accommodated, such as 458 Winchester, 416 Remington, 375 H & H, 338, 340 
Weatherby, 300 Winchester, 300 Weatherby, 7 mm Remington, 264, and 257 
Weatherby. The same receiver block design can be used for each different 
barrel. The same bolt is utilized for each of the standard calibers, and 
the bolt should be long enough to extract the longest of the cartridges in 
the standard used calibers. Normally, a second rifle bolt will be provided 
for the magnum calibers. The magnum rifle bolts generally only differ from 
the standard bolt in the configuration of the face of the bolt which meets 
the rear of the cartridge. Again, the length of the magnum rifle bolt 
should be of a length sufficient to extract the longest of the cartridges 
in the magnum calibers. For convenience, we will refer to the combination 
of the receiver block 10 and barrel 50 as the interchangeable barrel 51. 
Thus, a hunter may take in a convenient-sized case, a stock with the 
trigger assembly and the bolt and bolt guide assembly as one piece, and 
one or more interchangeable barrels. For example, he can take a magnum 
barrel for large game and a smaller standard barrel for smaller game. 
Furthermore, each interchangeable barrel is preferably equipped with a 
sight system, such as a scope, mounted on the interchangeable barrel. In a 
preferred embodiment, each interchangeable barrel will be mounted with a 
separate scope. Once the sight is aligned for that interchangeable barrel, 
there is no need for rezeroing each time the barrel is removed and 
replaced. Thus, the first practical interchangeable barrel is provided for 
a hunting rifle where accuracy is required. 
FIG. 5 shows an exploded view of another embodiment. In FIG. 5 is shown 
base piece 80 having a first end 82 and a second end 84. On the first end 
of base piece 80 is mounting member 86 for mounting of receiver block 10. 
Base piece 80 also includes magazine well 88, shown in phantom, for the 
receipt of drop-in magazines for the different types of cartridges which 
can be used with the rifle. In this embodiment, base piece 80 receives a 
sliding bolt assembly 90, shown in phantom. The second end 84 of base 
piece 80 is attached to stock 92, shown in phantom. Mounting member 86 is 
provided with alignment channel 94 for receiving alignment member 22. 
Aligning surfaces (not shown in FIG. 5) are also provided on member 86. 
FIG. 6 is a frontal view of base piece 80 showing alignment surfaces 96 
which are designed to mate with corresponding alignment surfaces on 
receiver block 10. A passageway 98 is provided through member 86 for the 
passage of a screw to draw down and removably affix receiver block 10 to 
mounting member 86. The same features regarding the alignment surfaces as 
discussed with the previous FIGS. 1-4, also apply to the embodiment shown 
in FIGS. 5 and 6. FIGS. 5 and 6 illustrate that it is not necessary for 
the bolt assembly 90 to be rigidly attached to the mounting member 86 for 
attaching receiver block 10. By use of base piece 80, the barrel may be 
rigidly attached to the base piece 80 and bolts slidably engaged to base 
piece 80 such that the locking lugs of the bolt cooperate with the locking 
lugs of the receiver block 10. 
Base piece 80, and in particular mounting element 86, should be of a 
dimensionally stable material which is nondeformable. Dimensionally stable 
materials may be steel, aluminum, steel alloys, some very hard plastics, 
or other materials. Most wood is not considered dimensionally stable or 
nondeformable. Wood will swell and shrink with variations in moisture and 
temperature. Further, wood being relatively soft, will give way and 
compress under sufficient pressure, such as that exerted by a screw. Thus, 
the mounting element must provide a rigid connection between the 
interchangeable barrel and either the base unit or the bolt guide assembly 
(as the case may be) to provide consistent zeroing. It may be possible to 
treat certain woods with plastics or other material whereby they could be 
rendered dimensionally stable and be used for the mounting element, if 
such treatment would produce a mounting area that was dimensionally 
stable. 
In the preferred embodiment, there are two alignment structures. The first 
is the alignment structure which provides proper alignment along axis C--C 
to provide proper positioning of receiver block 10 at a point along axis 
C--C such that when the rifle bolt is closed, locking lugs of the rifle 
bolt and of the receiver block will be held tightly together. The 
alignment surfaces principally serve to align axis B--B and axis A--A such 
that they form the single axis C--C which is substantially straight. This 
function is also served by alignment member 22. Thus, many other shapes 
may be utilized which achieve these same purposes. Thus, for example, in 
FIG. 7 a receiver block 100 is shown which has an alignment channel 102 
and an alignment member 104. It is provided with threaded passageway 106 
for receiving a threaded bolt. Mounting member 108 has an upwardly 
protruding alignment member 110, alignment channels 112 (shown in 
phantom), and passageway 114 for passage of a screw to engage threaded 
passageway 106. FIG. 8 shows an end view of the apparatus of FIG. 7. It 
shows that alignment member 104 is in the shape of a " V" and is received 
by a corresponding V-shaped channel 112 in mounting member 108. The "V" 
formed by surfaces 104 is truncated and has a flat bottom 105. This 
provides clearance between the bottom 105 and channel 112 when the pieces 
are drawn together. Thus, small particles of dirt in the bottom of channel 
112 will not interfere with the fit. Thus, channel 102 and alignment 
member 110 cooperate to properly align the receiver block at a point along 
the axis defined by the rifle barrel. Surfaces 104 cooperating with 
V-shaped channel 112 function to align the axis of the bolt with the axis 
of the barrel such that they form a single axis. 
FIGS. 9a and 9b show yet another embodiment, where FIG. 9a shows the side 
view and FIG. 9b shows an end view. In FIG. 9a, receiver block 120 is 
provided with an alignment member 122 disposed along the axis D--D of the 
receiver block and is provided with a threaded passageway 124. Mounting 
member 126 is provided with a corresponding channel 128 and passageway 
130. Like numbers refer to like elements in FIG. 9b. In this embodiment, 
positioning of the receiving element along axis D--D is achieved by 
alignment of passageways 130 and 124 and the passage of a screw 
therethrough. Alignment of the axis of the receiver with the axis of the 
bolt is achieved by alignment protrusion 124 engaging channel 128. Thus, a 
number of other possible constructions also may be used. 
The releasable attachment structure may be of any suitable construction 
which provides for releasable mounting of the receiver block onto the 
mounting member of either the base or of the bolt guide assembly, as the 
case may be. FIG. 9c shows a partial side cross-sectional view of an 
alternate embodiment. It shows receiver block 150 generally in the shape 
as described before. However, a chamber 152 is provided in depending 
element 154 which has a slotted opening 156. See FIG. 9e. The slotted 
opening receives a t-shaped retaining bar 160. The t-shaped retaining bar 
160 is held in base 162 which defines a passageway 164 having an upper end 
166 and lower end 168. The upper end of the passageway has a shoulder 170 
which acts as a spring stop for spring 172. Spring 172 acts upon spring 
engaging surface 174 of the t-shaped retaining pin 160 and provides 
tension downwardly. The lower end 168 of passageway 164 can be threaded to 
receive nut 176 which holds the bar 160 and spring 170 in the base 162. As 
shown in FIG. 9d, which is a top view of the base 162, and FIG. 9e, which 
is a bottom view of the receiver block 150, when the head of the t-bar 160 
is properly aligned it will pass through the slit opening 156 in the 
bottom of receiver block 150. After passing through, the t-bar is rotated 
in chamber 152 such that the edges of the bar 160 cannot be withdrawn 
through the slot 156. As shown in FIG. 9c, the spring tension of spring 
172 pulls the t-shaped bar 164 and the receiver block together. To 
disassemble the rifle, the spring 172 is compressed by pushing on handle 
178. The t-shaped top 180 of bar 160 is rotated until the bar may be 
extracted through the slot 156. As shown in FIGS. 9c, 9d and 9e, a channel 
182 is provided to receive alignment number 154 to properly index the 
receiver block 150 with the remaining rifle parts not shown. 
In another embodiment shown in FIG. 9f, a threaded bolt 190 may be part of 
the receiver block 192 either formed integrally therewith or attached 
therewith by welding or other suitable methods. This threaded bolt then 
passes through a passageway such as passageway 38 shown in FIG. 1, and a 
nut may be threaded on the end to pull the receiver block and the base 
together. In yet another embodiment shown in FIG. 9g, the releasable 
structure may be composed of a spring clamp 200 acting on a clamping 
surface 202 of receiver block 204. As shown in FIG. 9g, spring clamp 200 
is mounted on base 206. The clamp 200 shown is a spring action weighted 
clamp; however, a threaded clamp could also be used. As shown in the 
figure, the spring clamp 200 is mounted on base 206. It is comprised of a 
lever arm 208. On the first end, the lever arm is mounted to clamping jaw 
210, which is preferably mounted on a pivot pin 212 so that it may pivot. 
On the second end of lever arm 208 is the surface for manipulation 214. 
Placed along the second end is a spring 216 which forces the second end of 
arm 208 outwardly about arm pivot pin 218, thereby pushing clamping jaw 
210 inwardly into contact with the receiver block 204. To release the 
receiver block 204, the second end 214 of the lever 208 is pushed 
inwardly, thereby causing the clamping jaw 210 to rotate out to the 
position shown in phantom. The receiver block 204 may then be slid over 
and up. As shown, the base has one permanent side 220 having an angled 
shoulder 222 forming one side of a dove-tail, and the clamping jaw 210 
acts as the other side of the dove-tail. Alternatively, the clamp could be 
designed so that the clamp jaws constitute both sides of the dovetail. 
FIG. 9h shows a side view of the embodiment shown in FIG. 9g. The base 206 
is provided with channel 222 to receive alignment structure 224 extending 
from receiver block 204. 
The foregoing description of the invention is illustrative and those 
skilled in the art will appreciate other variations of the invention not 
explicitly shown may be used.