The .50 BMG 800 grain boattail bullet pen

 

This is by far the most popular pen we sell and also one of the most difficult to make.

It uses the standard .50 BMG once-fired cartridge for the base of the pen. The pen tip is milled from a real 800 grain solid brass boattail bullet that we order from reloading suppliers. The tip of the bullet is blunted to allow for drilling, then a 5/64th inch hole is carefully drilled through the tip to allow the pen cartridge to extend and retract.

This is a picture of the unmodified bullet...
...and after the milling is complete and the transmission is installed

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The biggest challenge is getting the tiny hole drilled into the tip of the bullet:

Due to the stresses placed on the tiny drill bit, we lose about 20% of the bullets to tear-outs and broken bits. That's why the 800 grain bullet pen is one of the most difficult pens to make.