Design of Tube Magazine Fed Bolt Action Rifle—Caliber .30-30 Winchester

ET 494: Senior Design II

Advisor: Dr. Junkun Ma

Instructor: Dr. Cris Koutsougeras

Student: Dallas Clayton Daigle

Table of Contents.

1. Abstract………………………………………………………..…2

2. Background……………………………………………………....3

3. Objectives…………………….....………………....………….....6

4. Mechanism Description……………………………………….…9

5. Breakdown of Designed Components and Methods…………......10

6. Cost Analysis…...………………………………………..……....38

7. Deliverables………………………………………………….......39

8. Conclusions……….………………………….……………..……40

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1. Abstract

The focus of this project is to design and model an action and components for a firearm

chambered in .30-30 Winchester that is fed from a tubular magazine running under the barrel of

the firearm, much like the popular Marlin 336. However, unlike the Marlin, this design utilizes a

bolt action, rather than a lever action. This objective of this design is to eliminate the problems

with the Marlin’s lever action design, namely the fact that it has an exposed hammer that needs

to be manually depressed to decock it, which is a large safety concern. Using a bolt action

instead of the lever action will allow the exposed hammer to be removed, and put in its place a

safety mechanism that completely disengages the firing pin, creating an action that is much safer

for shooters. The final design will consist of an internal mechanism designed around a bolt action

that will reliably and safely move a round from the magazine to the headspace of the barrel while

preventing another from leaving the magazine, fire this round, and extract and eject the spent

round; repeating this cycle until the magazine is empty.

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2. Background

The Marlin 336 is a classic firearm that is beloved by many. However, it was designed in

1948, and it is based on a design from 1893, and is not without flaws. It is the one of the highest

selling American firearms of all time, surpassed only by the Winchester Model 1894, which is

also made for the .30-30 Winchester. This shows that there have been little to no significant

design developments surrounding the heralded .30-30 Winchester cartridge in many years. The

following design, when complete hopes to change that by eliminating some of the issues that the

standard lever action design has.

Fig 1. Marlin 336 diagram.

Figure 1 shows the working parts of a Marlin 336. The mechanism’s lever action design

utilizes an exposed hammer to strike the firing pin and discharge the round. This is fine, unless

the user decides that they do not wish to fire upon their target. In which case, they must pull

trigger, and with their thumb on the hammer, control it as it moves down into the safe position.

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This can be extremely dangerous for inexperienced shooters, as they may accidentally release the

hammer, and cause a negligent discharge that could lead to property damage, or worse. It is also

worth noting that figure 1 shows many moving parts, which in the event of a complete

disassembly or repair, can prove problematic.

Figure 2. A simple/standard bolt action.

Figure 2 shows a diagram of a standard bolt action. Notice how the exposed hammer is

removed and that the firing mechanism is contained within the bolt by having the firing pin

under spring pressure. In this way, when the trigger is pulled, it releases the tension on the firing

pin, which moves forward and strikes the primer on the round. This design allows for a safety

mechanism that can totally disengage the trigger from the bolt, which is much safer than having

to manually depress the hammer. The bolt action also allows for fewer moving parts inside the

action’s housing/receiver, which leads to increased simplicity and reliability. Problems with bolt

actions arise when rounds like the .30-30 Winchester are considered. As figure 3 shows, it is a

rimmed cartridge, which often causes feed problems from the box or internal magazines

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commonly seen in bolt actions because the rim frequently catches on carriers on feed ramps. This

is why tubular magazines are the commonplace for this round.

Figure 3. Dimensions of the .30-30 Winchester.

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3. Objectives

The principal objective of this project is to design and develop a mechanical feeding/firing

mechanism that can reliably and safely complete the firing ejecting feeding reloading

cycle. The final mechanism needs to repeatedly perform this action under the many stresses

applied by the different individual movements of metal parts within the action. The

chamber/barrel/headspace needs to be designed to handle a working pressure of 42,000psi

(290Mpa). It must also be able to handle variable or dynamic working pressures from rounds

with a weight range of 125-180 grains, where 1 grain=1/7000th of 1lb. The magazine assembly

will need to hold 5-7 rounds and be able to load them into the action singularly. The whole

system should also be light and compact, with internals that are simple and reliable. It needs to

be easily disassembled for cleaning, and need little maintenance to run smoothly. For this, the

494 semester, the main objective(s) were to modify, redesign, and test the early prototype design

constructed last semester; build a 3D SolidWorks model of it such that the design may be tested

and simulated until deemed finalized and functional; and then to produce a 3D printed physical

prototype model for final function analysis and display. The methods to which the SolidWorks

model was constructed will be covered in section(s) 5 and onward.

Initial research, discussion, and conceptualizing early on last semester led to a design utilizing

a round carrier sitting atop multiple leaf springs that would be compressed by the force of the

magazine spring pushing the round onto the carrier. The carrier and round would then be pushed

up by the leaf spring force, where the round could be picked up by the bolt and loaded into the

headspace. In short—there is no way this design would work. It would be too complicated and

rely too heavily on the magazine spring for it to be feasible.

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Through more discussion, researching, and conceptualizing, the following mechanism shown in

figure 4 was decided to be the most suitable to meet the needs described previously. Figure 4 was

created by modeling each individual part in the CAD software SolidWorks, then using the mate

command in the assembly mode of SolidWorks to form the complete prototype model of the

mechanism. While this was a valid design in concept, in practice it did not meet the needs for

this project yet. The prototype modeling, simulation, and analysis processes exposed multiple

design flaws that needed to be revised and repaired, namely at the interface between the carrier

and the receiver, so those two items had to be re-designed. The re-design of these parts and

interferences led to other parts and areas needing to be revised or re-designed also, leading to the

finalized design shown in figure 6.

Figure 4. A 3D model that was constructed in SolidWorks showing the outer assembly with

visible hidden lines giving a view of the inner mechanism(s). Created last semester.

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Figure 5. A 3D exploded assembly diagram showing the individual parts of the mechanism.

Created last semester.

Figure 6. A 3D model that was constructed in SolidWorks showing the outer assembly with

visible hidden lines giving a view of the inner mechanism(s).

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Figure 7. A 3D exploded assembly diagram showing the individual parts of the finalized

mechanism.

4. Mechanism Description

The mechanism shown is centered around the carrier, which is shown in figure 8. The carrier

is the most important part of the entire system and has been designed to not only transport the

cartridge from the magazine to a position where it can be picked up by the bolt, but also to act as

the magazine retention device when the bolt is in its open most position, and to engage the

secondary magazine retention when the bolt is fully closed. It is held in place by a pin that allows

it to pivot upward and downward, as shown in figures 5 and 7.

The mechanism functions as follows: When the bolt handle is rotated upward and the bolt is

pulled back, a leaf spring applies an upward force on the carrier causing it to travel upward in an

arc. This allows the magazine retention device to be disengaged into a rest position, and for a

round to move backward onto the carrier. As the bolt continues to move backward, the carrier

continues to move upward on its arc into its resting position, placing the new round in position to

be picked up by the bolt when it travels forward. While the bolt is fully opened and the carrier is

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in its resting position, the feature on the bottom front of the carrier acts as a magazine retention

device, effectively keeping other rounds from exiting the magazine during the charging cycle. As

the bolt starts to travel forward, the round is moved forward into the headspace or into battery.

As this forward motion happens, the bolt face runs along the ridge of the carrier, pushing it down

into position where it re-engages the magazine retention device to prevent the magazine from

emptying itself.

5. Breakdown of Designed Components and Methods.

The following sub-sections will break down and discuss the design, function, dimensions, and

placement within the mechanism of each individual component. Each section will show last

semester’s model, followed by the current one and discussion of the changes. All parts were built

in the Computer Aided Design software SolidWorks. The construction of each part will be

discussed in their respective sections.

Before any model could be created however, the needed geometry had to be established. For

many cases, it was an assumption based on the dimensions of the round, which are shown in

figure 3. Since this is a new design, most of the dimensions were left to my discretion. Because

of my being new to SolidWorks, I attempted to design and dimension all of the parts by hand

before modeling. This proved to be a huge waste of valuable time and energy because as I

discovered, the dimensions are almost constantly changing due to different changes in part

geometry and understanding. It would have been a far better investment of time to just go into

SolidWorks and dimension as I went.

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5.1 The Carrier.

As mentioned previously, the carrier is the most important part of the entire mechanism. Its

leaf spring assisted pivoting allows it to act as transport for the round from the magazine to the

headspace, act as the secondary magazine retention device when the bolt is open, and to engage

the primary magazine retention device when the bolt is closed. The unique geometry of the

carrier was specifically designed to meet those demands. Referencing figure 8, it can be observed

that the carrier has several geometric features that allow it to be a multi-functional component of

the mechanism. By designing the carrier in such a way, the entire mechanism can be simplistic,

which aids in both reliability and disassembly. However, the uniqueness of the carrier could

cause it to be difficult to manufacture initially, but that issue is inherent in most any design

component that is newly designed or custom.

The design shown in figure 8 was a good start, but it would take a further 5 versions before I

settled on something that could be called finalized. The design length from last semester was too

short, which led to an insufficient arc length, and a considerable gap between it and the

headspace when in its upmost position. The walls also needed to be thinned to allow for a better

fit, and the right side needed to be tapered towards the front to allow the pivoting action to be

fully effective. These changes can be observed in figure 9.

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Figure 8. Carrier design model from last semester.

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Figure 9. 3D SolidWorks model of the round carrier. Note the geometric features that allow the

carrier to serve multiple purposes, such as the ridge that allows the carrier to be forced

downward by the forward motion of the bolt, the lip on the bottom front that acts as the

secondary magazine retention when the bolt is open, and the taper that allows it to pivot to an

almost resting position.

Before the carrier could be modeled, its travel arc needed to be calculated to establish the path

that the carrier takes when pivoting. To do this, I needed to acquire the arc length of travel using

the formula(s):

S=θr. Or S=2 r∗π∗θ360°

Where S is Arc Length, θ is the travel angle in degrees, and r is the arc radius. Doing a quick

trig calculation using a predetermined y travel of .645” and the following formula gives us our

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angle, which is then plugged into the formula above with the known radius of 5.5” to give our

arc length. This arc helps establish the dimensions for the secondary magazine retention device.

tan−1 .645 } over {5.5=θ=6.69 °

S=2(5.5 )∗π∗ { 6.69° } over {360 ° } =.642 ”

To build the carrier, a .66” by 1” square was drawn on a plane in the sketch mode of

SolidWorks, then extruded 5.5” using the boss extrude command. This created a .66” by 1” by

5.5” block that represents what one might start with in a machine shop. The ability to create

blocks of material and use the extrude cut command to cut out geometric features is highly

advantageous because it allows the drafter or designer to create his or her models with the end

fabricator in mind.

Figure 9. The .66” by 1” by 5.5” block that was created in SolidWorks and used as the starting

point for creating the carrier geometry.

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After creating the starting block, a new sketching plane was created on front face, and on it, a

rectangle was drawn. This rectangle was .35” from the bottom, .508” wide, and it went through

the top. The extrude cut command was then used to cut out this channel 2.65” inches deep into

the block to create the channel for the round to ride in once it leaves the magazine. The carrier

has a hole bored through the side, 3.85” from the front. This hole is where the retention pin will

go to hold the carrier in place. This pin is also the support that allows the carrier to rotate around

the center point of the pin, while preventing the carrier from moving in the X or Y direction. This

is known as a pinned support in Strengths of Materials.

Figure 10. The process used to create the channel for the round to be transported. Also note the

pin hole.

To create the ridge that moves the carrier down, a similar process was used. In this case, a

sketch plane was created on the side of the carrier, and on it, the outline of the ridge was created,

as shown in figure 11. Then, the extrude cut command was used to remove the material

necessary to leave the finished geometry. Because having two ridges would prevent the carrier

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from moving up into the bolt path, one of them needed to be leveled off. To do this, another

sketch plane was created, this time on the rear. A rectangle that contained all the material I

wanted to remove was created, which in this case was the rightmost ridge when observing from

the rear. Then, the extrude cut command was used to level off the right side of the carrier,

leaving just the one ridge to control the location of the carrier relative to the bolt.

Figure 11. The sketch plane showing the outline of the geometry used for the creation of the

carrier ridges in SolidWorks.

The same methodology was used to create the rest of the geometry: Create a plane, draw a

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sketch of the geometry, then boss extrude or cut extrude to add or remove material to create the

needed geometry. The creation of the magazine retention lip can be observed in figure 12.

Figure 12. Creation of the magazine retention lip or secondary magazine retention device in

progress.

Since the processes for creation of the geometry on subsequent parts were fundamentally the

same, they will be touched on more briefly than in this section, unless they need to be expounded

upon.

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5.2. The Barrel.

Initially, the intention was to completely design a new barrel. One that had the ideal amount of

rifling, was the ideal thickness to remain safe under the round’s pressure, and was harmonically

stable to achieve maximum accuracy. However, after doing the calculations for the needed barrel

thickness and ideal rifling ratio, I discovered that the standard barrels available are already very

close to the ideal case, so a custom job was no longer necessary. For redundancy purposes, I

went ahead with my calculations, but only used the ones for the headspace pictured in figure 14,

and not the entire barrel. That data is as follows.

To find the minimum safe thickness of the barrel/headspace, I needed to use the thin-walled

pressure vessel model. The maximum chamber pressure for the .30-30Win is 42ksi. This will be

used as our internal pressure. The diameter of the .30-30Win is .308”. This will be used as the

inner diameter. I chose a barrel length of 20in. Consulting the Statics and Strengths of Materials

Textbook by Robert Mott, I decided that based on the load conditions, a design factor of 2 should

be used. Understanding that stress equals force per unit area, I came to the conclusion that the

stress (In this particular case, thin-wall Hoop Stress) will be its maximum at the headspace, and

its minimum at the muzzle, so the headspace should be considered first. Through one of SELU’s

faculty, Mrs. Amanda Brown, I was put in contact with a former metallurgist from Remington

who informed me that the standard material for firearms purposes is ANSI 4140, so that was

chosen as the material for this project. ANSI 4140 OQT900 has a yield stress of 173ksi, and with

the chosen design factor of 2, this gives us the design stress: σ d=173 ksi

2=86.5 ksi.

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Now that all the necessary data has been compiled, the necessary wall thickness and outer

diameter can be found using the “gunsmithing version” of the thin-walled hoop stress equation,

which is as follows:

σ=(P)(Di)

2(t)

Where P is the pressure, Diis the inner diameter, and t is the wall thickness, which is the

unknown in this case. After re-arranging, and inputting all data, the needed wall thickness can be

found:

t=¿¿

Now that we have the necessary wall thickness, we can find the outer diameter, or Do by doing

the following calculation(s):

Do=Di+2 (t )=¿

To find the diameters and wall thickness at the muzzle, the same calculations must be done,

but with the addition of Boyle’s Law (P1V 1=P2V 2 ¿ to find the equivalent pressure at the

muzzle. After calculating the volumes and re-arranging, we get the pressure at the muzzle and

can solve for the wall thickness and diameter at the muzzle.

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P2=P1V 1

V 2=

(42 klb¿2 )( .121¿3)

1.49 ¿3 =3.407 ksi

t=1.05 ksi∗¿

86.5 ksi=.012= Wall thickness

Do=Di+2t=.308 + 2(.012¿=.332 = {D} rsub {o

The above calculations were perfomed for an ideal case where no friction exists, and the

rifling lands and grooves are not present. The real values for the muzzle end would be much

thicker. In fact, the outer diameter would be almost the same at any cross-section throughout the

length of the barrel. Using another formula, the ideal rifling twist rate could be found. That

formula is:

Twist Rate=3.5∗V 0.5∗D2

L

Where V is the velocity, D is the round diameter, and L is the length of the round. When

inputting the necessary parameters, the result is that the ideal twist rate is 1:12” or 1 full rotation

every 12 inches, which is the standard for this round. This discovery, combined with the above

calculations, led to the decision to use a standard barrel if this design were to ever go into

production.

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Creating the 3D model of the headspace was relatively simple. After sketching half of the

geometry around a center line, the revolve extrude command was used to extrude the sketch

around the center line to build the model shown in figure 14.

Figure 13. Current 2D representation of the headspace resulting from calculations and created in

SolidWorks.

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Figure 14. Current 3D model of the headspace sectioned to show the inner geometry. Created in

SolidWorks.

Some changes were needed for the headspace/chamber design for this semester. The addition

of an improved functional extractor to the bolt model (Section X.Y) led to some small

dimensional changes and a remodel because of dimensions being dependent on each other. I also

noticed when preparing the models for 3D printing and analysis that the end dimensions on the

model were completely wrong, which meant I had modeled it incorrectly, and that it had to be

redone. The use of parametric design was useful here because I was able to simply change the

driven dimensions and rebuild the model instead of starting from scratch, which saved

considerable time. The current models are shown in figures 13 and 14, with the previous models

shown in figures 15 and 16.

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Figure 15. Previous 2D representation of the headspace resulting from calculations and created in

SolidWorks last semester.

Figure 16. Previous 3D model of the headspace sectioned to show the inner geometry. Created in

SolidWorks last semester.

Once the model was complete and correct, I was able to legitimately put my calculations and

data to the test of Multiphysics simulation and analysis through use of the software COMSOL.

Once I saved the SolidWorks file of the headspace in a STereoLithography (.STL) file format, I

was able to import the model into COMSOL for analysis. Once the model was imported and the

geometry was established, I could establish the parameters for analysis. I chose structural steel as

the test material instead of creating a new one to save time. Structural steel is actually a weaker

material than what I used in my design calculations, but this will actually be advantageous

because it illustrates the level to which my design was over-engineered. I declared a stationary

study with solid mechanics physics because I wanted to observe the effects of stress/strain and

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force/pressure at a singular moment in time. Under boundary conditions, I set the front and rear

of the model as being fixed to simulate them being mounted to the barrel and receiver, then

declared a 290mPa (42ksi) load on the inner wall of the chamber. In this way, I could observe the

stress in headspace at the moment of firing and check for stress concentrations or failures. I

formatted the model with a normal mesh, to ease the load on the computer to expedite the

calculation time. I set up the study to calculate the distribution of the 1st principal stress, then

produce a 3D plot of the stress distribution across the model with exaggerated deformation.

Observing figure 17, it can be seen that there are no major stress concentration that could point to

a structural failure, and that the overall stress is relatively low, which shows that my design is

valid and strong.

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Figure 17. COMSOL model showing the 1st principal stress distribution across the model with

exaggerated deformation.

5.3. Magazine Retention Device.

The magazine retention device is extremely important because it regulates the cartridges

leaving the magazine. In this case it makes sure that only one cartridge leaves the magazine per

loading cycle. It basically functions as a simple lever. When the round carrier comes down, the

lip on the bottom pushes down on one end of the device, which pushes the other end up as it

rotates on its pin, blocking the exit of the magazine and preventing more rounds from leaving

and causing feeding problems. To create its model, all that I needed to do was draw its outline on

a sketch plane, and boss extrude it to create the main geometry. Then, after creating another

sketch plane on the top, two rectangles were drawn on this plane and cut extruded to make the

device fit in the groove in the magazine tube.

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Figure 18. 3D model of 1st magazine retention device. Created last semester.

The model shown in figure 18 is the version 1 model that was created last semester. The

changes in the carrier, receiver, spring setup, and overall configuration led to a necessity to

redesign this part. The redesigned magazine retention device is shown in figure 19. The overall

design changes actually allowed this part to become simpler in design, which is a positive

change. The length was shortened, the part was made slimmer, and the location in the overall

assembly was changed slightly to compensate for the increased length of the carrier and to allow

for the addition of its operating spring.

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Figure 19. Current (3rd) iteration of the magazine retention device.

5.4. Tubular Magazine.

After some online research, it was discovered that a standard tubular magazine for the .30-

30Win had an outer diameter of .650” and an inner diameter of .560”. This made modeling the

magazine a relatively easy task. A circle with the above dimensions was created and boss

extruded to create the main body, and then a rectangle was drawn on the front plane and extrude

cut was used to create the geometry for the magazine retention device. Noting figure 20, it can be

observed that there is no clearly defined method to which the magazine end cap and spring will

be affixed. This is because the model shown in figure 20 is the 1st iteration from last semester.

For this semester, I used the extrude cut command in SolidWorks to design and create a sort of

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rotating locking lug to hold the endcap, and thus the magazine’s internals, in place. These

changes can be observed in figure 21.

Figure 20. 3D model of the 1st magazine design in SolidWorks. Created last semester.

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Figure 21. Current 3D model of the tubular magazine. Note the addition of the locking lug

channel for the end cap. Created in SolidWorks.

Once I created the tubular magazine and its functional components (Follower and End-Cap) I

mated them into a mechanical assembly using the assembly mode of SolidWorks. This assembly

is shown in figure 22. Also, once I started construction of the final assembly, this mechanical

assembly was incorporated into that assembly as a sub-assembly.

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Figure 22. Magazine assembly completed in SolidWorks assembly mode with hidden lines

showing the internals.

5.5. The Bolt.

For this project, it was my original intention to use a standard bolt because designing an

operational bolt from scratch is a project that would take more than a year by itself. Because of

cost and availability, I decided to design around the Mosin-Nagant bolt, which is pictured in

figure 23. This bolt was chosen because I currently have two on hand, and acquiring a firing pin

that can be made inert for legality/display purposes would have been an easy and inexpensive

task. However, this choice had major downsides. The design for this bolt is old, with its current

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iteration being produced since 1891. Because of this, no solid dimensions could be found

anywhere (which is a problem that will come up again in section 5.6) for me to create a model of

this bolt to use in the SolidWorks assembly. To get around this, I created a pseudo-model using

the outer diameter of the bolt (which I was able to find) to use in the 3D model. Using what little

data I could find, I created and designed a bolt rear and bolt body based on the Mosin-Nagant

bolt (complete with extractor and ejector channel) that could fit together and be used in the

physical model for basic cycling function. This bolt would in no way be close to real function,

but could be used in a physical prototype model to simulate bolt handle rotation behavior and

basic mechanical function. The bolt rear and body are shown separately in figure 24, and

assembled together in figure 25.

Figure 23. The Mosin-Nagant bolt considered for the design.

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Figure 24. 3D model of bolt body and bolt rear separately. Created in SolidWorks.

Figure 25. Bolt sub-assembly. Created in SolidWorks assembly mode.

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Analysis for the bolt was relatively simple. Once the .STL file was imported it was as simple

as setting the boundary conditions and load on the locking lug, and letting solver do its job. The

stress distribution is shown in figure 26. The only area of concern is the base of the locking lug

where there is a relatively heavy stress concentration. Adding a fillet in that location would

alleviate this concentration.

Figure 26. COMSOL generated 3D stress plot showing distribution and exaggerated

deformation.

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5.6. Receiver/Housing.

Last semester, I had initially intended to use the Mosin Nagant receiver that went with the bolt

previously discussed in section 5.5. Throughout a large portion of last semester, I was designing

with that receiver in mind. However, when it became time to model everything, I ran into the

same problem from section 5.5. The age of this design made it to where there were no accurate

or legible dimensions to use to model the receiver. Because of that, I was forced to design a new

receiver/housing, and I have been modifying it to fit the needs of this design ever since. There

have so far been seven different iterations of the receiver that I have designed and modeled, and

it is still imperfect, but effective enough for the needs of a prototype. The early (Left-handed)

version is shown in figure 27, with the most recent one in figure 28.

Figure 27. The early receiver design from last semester.

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Figure 28. The current receiver design. Note all of the features allowing it to effectively house its

components.

For this semester, I designed many features on the receiver to allow it to be an effective

housing. The pin holes were moved and changed to account for changes in part geometry, a cut

was made in the left front to account for the larger ridge on the carrier, features were added on

the bottom to attach the bottom floorplate that was discussed last semester to facilitate cleaning

and disassembly, and tolerances were changed and improved across the board. Also, an area to

attach the barrel was modeled, but not threaded due to a lack of standards.

Despite all of these improvements, it is still imperfect, namely in the Strengths of Materials

department. When I originally came up with the design, it was simply a housing to contain the

functional parts of the mechanism. A display model, if you will. Over time, this housing has

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evolved into a functional part of the mechanism itself, which means it has become a theoretically

load bearing part because the pressure from the detonation of the powder would be transferred

through the bolt and into the receiver as an equivalent force. The problem is that, as the

receiver/housing has in theory evolved into a load bearing element, its geometry has not. This

was evident when I ran the analysis on this part. As evidenced in figure 29, if the receiver is

exposed to the full equivalent force of the rounds firing pressure, there is a catastrophic failure.

Figure 29. 3D plot of the stress and deformation on the receiver when subjected to the total load

of the force at the moment of detonation. Created in the simulation module of SolidWorks. This

would be considered a catastrophic failure in the firearms world.

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Figure 30 shows how the distribution of stress should look. There is a stress concentration in

the lower corner (Where it would be wise to place a fillet) but limited deformation. To achieve

this, I had to lower the load force by a full magnitude. This analysis shows that the receiver is not

strong enough to manufacture as is for any task other than a display variant, which was the

original intended purpose. If I were to increase the wall thickness in all areas by 70-100% while

maintaining all inner dimensions, I believe it would hold up effectively. This would not be a

hugely difficult task, but there is not enough time left for that kind of modification at this stage.

Figure 30. 3D plot showing stress distribution under a lessened load at the moment of firing.

Created in SolidWorks simulation module.

The reason the analysis for this part was done in the SolidWorks simulation module instead of

COMSOL was because the receiver was too complex to be imported into COMSOL from

SolidWorks. Doing the analysis in SolidWorks was actually easier and more intuitive, which I

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keep in mind for future reference. All I had to do was declare a material for the part, set up the

parameters (Boundary loads, fixed constraints, etc.) and let the study solver do the rest.

5.7. Other Hardware/Parts.

It can be noted in almost all of the figures in this document that none of the springs needed to

operate this design (Magazine Spring, Carrier Spring, Magazine Retention Spring, etc.) are

present. This is because the intension is to buy them and install them in the physical model,

rather than attempt to model them. In fact, I did model three of them. One of them is shown in

figure 31, but getting them to behave as springs in the models was next to impossible, so the idea

was scrapped in favor of simulating their presence in the SolidWorks animator. The same can be

said for the screws to hold the floorplate. They were not modeled because they would be bought

once the physical model is created.

Figure 31. Unused spring model created in SolidWorks. Modeling was dropped in favor of

simulation.

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6. Cost Analysis.

As far as cost is concerned, ideally the product would be priced competitively in comparison

with the main models on the market. However, it should also be somewhat cheaper than its

competitors as to draw customers to a new and currently unproven design. The Marlin 336 has

an MSRP range of $479.99 - $649.99, while the MSRP on the Winchester Model 94 is $1199.99.

The D-M1 also needs to be priced competitively with other bolt-action rifles, since it should also

be able to draw consumers from other bolt-action hunting rifles. The MSRP range for low to

mid-range bolt-action rifles is about $275.00 - $650.00. One of the main selling/design points of

this product would be its simplicity, which gives it a boost in reliability, but also allows it to be

sold at a cheaper price because of the increased ease in manufacturing. However, since it is a

completely new design, it would have to be sold at a higher cost initially because it has never

been manufactured before and thus companies must alter their manufacturing centers to allocate

the new product. After it has been manufactured for some time (1-2 years, most likely) the price

will be able to be dropped to a lower and more permanent point. Considering all of this data, it

would make sense to initially offer this product at a price somewhere in the range of $450.00 -

$550.00, and after some period of time, drop the range down to $250.00 - $450.00, depending on

sales/number manufactured.

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7. Deliverables.

Continue and complete a finished mechanism design.

Build detailed 3D model prototype in SolidWorks.

Hand/COMSOL analysis on system.

3D printed plastic display model of system.

Re-evaluated/Continued Cost Estimation.

All of my deliverables were completed in line with my timeline and proposed list of

deliverables, with the exception of one, which is currently ongoing. The 3D printed model has

been delayed due to a failure with the campus’ 3D printers. I prepared all of my files to be

printed, converted them to .STL, and sent them to be printed. It was that afternoon when the

printers went down, before any of my parts even made it into the printing queue. It is a very

upsetting series of events, but my advisor and I are doing our best to find a solution. The

University is supposed to get a new printer next semester, and Dr. Ma is going to let me know so

I can come have my parts printed. Until then, the 3D printing stage is in limbo.

9. Conclusions.

Overall, it has been an enriching and rewarding time working on this project and putting my

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skills to the test. At this point, I am satisfied with the level of progress that I have achieved on

this design, and even though it is far from perfect I feel that it is more than impressive for my

first solo design. Throughout this entire project there have been numerous obstacles and trials to

overcome. Almost every part in the design needed to be revised and redesigned several times to

meet the ever changing parameters and needs of the design. One of the most difficult, but also

most rewarding aspects of the project was learning the CAD software SolidWorks. It was

extremely hard to teach myself the ins and outs of such a complex program, but the skills I’ve

learned will prove extremely valuable in moving forward. There were many instances wherein I

ran across a problem in which I had to do heavy research to develop the skill or skills I needed to

make progress with the design. Those obstacles have taught me self-reliance and time

management, along with many other things that will certainly aid my professional career. . I

would like to thank my advisor, Dr. Junkun Ma, for his counsel and encouragement over the

course of this semester. I would also like to thank Mrs. Amanda Brown for her ongoing support,

and for helping me in gathering materials data for this project. And, of course, I’d like to thank

Dr. Cris Koutsougeras, for managing and overseeing this course and all the work that such a

large undertaking entails.

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