SPRING OPERATED SHOTGUN SPEED LOADER A Thesis Presented to the faculty of the Department of Mechanical Engineering California State University, Sacramento Submitted in partial satisfaction of the requirements for the degree of MASTER OF SCIENCE in Mechanical Engineering by Kit Winslow Spelman FALL 2015 © 2015 Kit Winslow Spelman ALL RIGHTS RESERVED ii SPRING OPERATED SHOTGUN SPEED LOADER A Thesis by Kit Winslow Spelman Approved by: __________________________________, Committee Chair Dr. Akihiko Kumagai __________________________________, Second Reader Professor Kenneth Sprott ____________________________ Date iii Student: Kit Winslow Spelman I certify that this student has met the requirements for format contained in the University format manual, and that this thesis is suitable for shelving in the Library and credit is to be awarded for the thesis. __________________________, Graduate Coordinator ___________________ Dr. Akihiko Kumagai Date Department of Mechanical Engineering iv Abstract of SPRING OPERATED SHOTGUN SPEED LOADER by Kit Winslow Spelman Statement of Problem To reload most modern day firearms a button is pressed to release the installed magazine and another magazine is inserted into the firearm. The second magazine has been preloaded with ammunition making the process quick and efficient way to reload a firearm. A shotgun does not have a detachable magazine which slows down the reloading process. Once all the ammunition from the shotgun‟s magazine has been depleted more shells are inserted through the loading port into the magazine one at a time. This process can take a long time since a shotgun can hold up to (8) shells. If someone practices and practices they can become very efficient at reloading quickly but this process is still not as fast or efficient as a detachable magazine. The purpose of this paper is to design a new invention that will auto feed shells into a shotgun quickly, and reliably as possible. This new design will be accomplished by designing a magazine re-loader that will house up to (8) shells. The shells will be pre-inserted into the loader ready for use. Once a shotgun is ready to be reloaded, this new loader will be held up to the loading port, activated by depressing a release button on the side, and a spring will load shells into the magazine of the shotgun. Since this method will be faster and more efficient that v reloading shells by hand, this product will be more appropriately called a Spring Shotgun Speed Loader or SSSL. Conclusions Reached The final design was not able to hold all (8) shells and keep the length of the SSSL a manageable size. The length of the final design is 35.33” long overall and can house up to (5) shells instead of the intended eight. Transferring all shells into a shotgun takes less than ½” second successfully and repeatedly. The goal was achieved in which the SSSL works and loads all (5) shells but the design could be improved to make the SSSL easier to use by shooter. A second iteration will come in the future that will address: ease of loading the shells into the loader, reduction of overall length and faster alignment to the shotgun. _______________________, Committee Chair Dr. Akihiko Kumagai _______________________ Date vi TABLE OF CONTENTS Page List of Tables .................................................................................................................................. ix List of Equations .............................................................................................................................. x List of Figures ................................................................................................................................. xi Chapter 1. INTRODUCTION ..................................................................................................................... 1 Background ........................................................................................................................ 1 Problem.............................................................................................................................. 2 Current Products ................................................................................................................ 3 Purpose .............................................................................................................................. 6 2. CONCEPT PROTOTYPE ......................................................................................................... 7 3. SPRING FORCE DETERMINATION ..................................................................................... 9 Why a Spring? ................................................................................................................... 9 Force Sensor Setup .......................................................................................................... 10 Force Sensor Measuremnt ............................................................................................. 104 Spring Sourcing ............................................................................................................... 17 4. DESIGN ................................................................................................................................... 20 Design Overview ............................................................................................................. 20 Shell Angle Determination .............................................................................................. 20 Angle Shell Prototype ...................................................................................................... 33 SSSL Alignment .............................................................................................................. 34 Shell Opening Determination .......................................................................................... 36 Push Button Release Design ............................................................................................ 42 vii Main Body Design ........................................................................................................... 44 Grip Design ..................................................................................................................... 46 Pusher Design .................................................................................................................. 48 End Cover Plate and End Stopper Design ....................................................................... 50 5. FABRICATION ...................................................................................................................... 53 6. TESTING ................................................................................................................................. 58 Release Button Testing .................................................................................................... 58 Pusher Testing ................................................................................................................. 60 Shell Loading ................................................................................................................... 63 Accidental Release Button Triggering Testing ................................................................ 65 Spring Testing ................................................................................................................. 67 7. ANALYSIS OF THE DATA ................................................................................................... 77 8. CONCLUSION ........................................................................................................................ 81 Appendix A Individual Part drawings ........................................................................................... 87 Appendix B Interlink Electronics FSR 402 Specifications ............................................................ 93 Appendix C Arduino Specifications .............................................................................................. 95 Appendix D Arduino Programming Code w/ 5 lbs. & 10 lbs. Verification .................................. 96 Appendix E Shotgun 12 GA. Shell Measurements ........................................................................ 99 Bibliography ................................................................................................................................ 100 viii LIST OF TABLES Tables Page 1. Force results from tests on loading shells. ..................................................................... 16 2. Testing springs specifications. ....................................................................................... 70 3. Spring test loading data, original training shells. ........................................................... 73 4. Spring test loading data, using new shells. .................................................................... 76 ix LIST OF EQUATIONS Equations Page 1. Voltage output equation. ................................................................................................ 12 2. Newton to Grams to lbs conversions. ............................................................................ 13 3. Hooke‟s Law .................................................................................................................. 70 x LIST OF FIGURES Figures Page 1. Parts of a shotgun. ...........................................................................................................