.308 Ammunition Case

This is a 3D-printed case I designed to hold 20 rounds of .308 ammunition. The silhouettes are extruded up just past the halfway point of the round giving it a secure hold and a satisfying 'click' when pressing in a round. It should fit brand or bullet tip style, as long as it has a normal .308 casing.

Key Features:

• Click-Fit Silhouettes: Each round is held in place, even when the case is shaken or bumped. After "rigorous testing" which consisted of using this as a fidget toy and clicking a round in and out a few hundred times, it has retained its firm hold. Although I'm sure it will wear with prolonged use, it should require a ridiculous amount of regular use before it would wear out.

• Print-in-Place: The entire model prints as one piece. The only supports required, are already included in the CAD design, so you don't have to consider that.

• Sealing: The case has a raised profile on one side and a corresponding groove on the opposite side. While not airtight, it provides a barrier to dust and grime, and aids alignment between the lid and base.

• Latching Mechanism: I gave this a 'bolt-action' style latch, it is rotated up and pulled back to unlock and slid forward and rotated down to lock. the tab fits flush with the profile of the case when in the locked position. (NOTE: For the time being I would avoid printing this in in 0.2 and above layer height. The pin has issues initially breaking free and rotating with thicker print layers , see print settings below.)

Future V2 Updates:

• The next version will include an actual TPU gasket for a tighter seal. My attempts in the current version to include a gasket didn’t perform as intended, so I’m reworking the latch mechanism for better, evenly distributed holding pressure to allow for a good seal.
• V2 will also introduce an optional spring-loaded bolt-action latch, utilizing a standard ink pen spring, making it easy for anyone to assemble without special parts. This feature requires minor assembly, so it will not be completely print-in-place like the current version.

My Print Settings:

• Printer: Bambu Labs P1S
• Nozzle: 0.4mm
• Layer Height: 0.12mm
  • 0.2 can work, but it has been prone to braking the tab off the bolt pin when trying to rotate the bolt latch initially after printing. (it can be done but takes some special attention and is a risk)
  • I suggest printing one of the test prints for the bolt latch before printing the entire case at 0.2 layer height. The test prints are just the latch section and take around 20 mins to print. They will let you test if it will work with your printer and settings before printing then entire thing.
  • I will update this once I have found the right combinations of tweaks to the model to allow 0.2 to print reliably.
• Material: Matte PLA (I plan to print in ABS for additional strength in future iterations)

Print Time: Approximately 7.5-8 hours with the above settings.

Feel free to test different materials or settings, but keep in mind I’ve only tested the design with the above materials and settings. Your results may vary.

If you have made it this far…

I’m currently working towards an engineering degree, and time for extensive model testing and refinement is a bit scarce. As a result, some aspects of the design might not be fully optimized, and occasional oversights will happen. For that reason, this model is and will remain available as a free download. I will continue to make improvements when possible and any feedback on the model is invaluable and always appreciated.

If you feel the design and final print have met your expectations, a “buymeacoffee” donation would be an appreciated gesture. You can contribute via the link here if you’re so inclined. https://buymeacoffee.com/overton_prints