Your customer has requested you service his favorite family heirloom - a World War II Arisaka Type 2 Paratrooper rifle (also called aTERA - Teishin Rakkasan Assault/Raiding Paratrooper).
After you take note of the serial number, you notice the retaining pin used to secure the barrel/forearm assembly to the receiver appears to be missing the D-ring. The D-ring is intended to aid the shooter in pulling the wedge to disassemble the rifle for transportation. After bringing it to the customer's attention, he has requested you create the D-ring.
1. If you can’t find a physical sample or blueprint of the part you are trying to create, how else can you get measurements for the part?
If I were not able to find any schematics or blueprints for a specific part I was trying to create, I would need to find another way to find the measurements for the part. You can start by looking at some older catalogs for the firearm in question. With the invention of the internet came endless knowledge and resources. Most things have been scanned and uploaded nowadays and with the right amount of searching you can find them. Even if the owner’s manual hasn’t been printed for 100 years, there will be someone out there who had the training material and has uploaded it. However, some firearms companies choose not to release their firearms schematics, and this makes things a little harder. If this is the case you may need to find a friend or another customer with the same firearm and ask them to inspect it for the part you were missing. This would allow you to get the exact dimensions of the part and even tell you what the part was made of. All else fails, start measuring the space the part occupied and make the new part based on those measurements. This can take some trial and error so take your time.
2. How might you determine the material to construct the part from?
It can assume that the part needed to fix the missing component on this World War II Arisaka Type 2 Paratrooper rifle would be made of steel. This is not always going to be the case, but this missing d ring on the pin that connects the barrel and foregrip to the rifle’s action and stock needs to be durable. This is the pin that threads into the rifle during assembly and not having the d ring to tighten or loosen the threaded pin can be a pain. A softer metal like lead or aluminum being used for this purpose could bend, break, or become distorted because the connection point is prone to stress while carrying and general usage. It is possible the original was a different metal and this is the reason it is missing. By knowing the purpose of the part, you can usually determine what material should be used to create it.
3. How would you test the part for quality?
Beginning with a high-quality steel usually is a good place to start if attempting to create a good quality part. Once the part has been machined you can check its fit and finish to ensure that the piece you created meets the need of the part that was broken or missing. Knowing it is a quality metal and that it fits my needs I would then move on to test firing the rifle but only if the customer intends to use the firearm. Because this is a family heirloom, it may not ever need to fire so be clear with your customer as to whether they want a functioning rifle or just a display one.
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