300 AAC Blackout cutting jig

prusaprinters

This is a jig for cutting 223 Remington / 5.56x45mm NATO cartridges down to 300 AAC Blackout cartridge size using a Chicago Electric 4" mini hobby table saw.  It has a dado on the bottom to fit the table slot just to the right of the blade, and a fitting on top for the cartridge to be cut.  Print this jig out of inexpensive PLA ( the cheapest that won't glop up your printer is fine) as it will be be getting some rough treatment and won't last forever.  There's no moving parts.  Give it at least 20% infill, it does not need to be solid.  Print upside down, with support from the base plate.  The make pictured used up a spool of green PLA before finishing in red.  To use: The jig is made for a specific purpose and requires careful adjustment and double checking to ensure the saw and jig can be used properly and safely.  Adjust the blade to be nearly the height of a shell's thickness.  Tighten the blade guard on the saw to allow the jig to pass underneath it.  Put on safety glasses and some good heavy leather saw gloves and turn on the saw.  Drop a 223 Rem cartridge in the top, and hold the cartridge in place (downward pressure with first or second finger) while applying some forward pressure to the jig and slide the jig and cartridge into the blade.  This is not an amazingly powerful saw (but it's cute!) and you'll be able to get about halfway through the cartridge before you have to let off the forward pressure and allow the motor to bring the saw blade back up to speed.  Two or three passes are usually necessary.  If the cartridge remains in contact with the blade too long, it will sink too much heat and begin to melt the plastic jig… if this happens slap the jig on the table upside down to dislodge the hot cartridge (when/if stuck to the jig) and finish that shell later after it cools.  Buying a saw blade that will handle brass will most certainly be worth the extra expense if you plan on converting a large number of shells.  The chopped shell needs to be formed using a 300 Blackout sizing die in a reloading press, followed by trimming the mouth to make the cartridge length the 300 Blackout trim-to-length of 1.348" - 1.368".  Toss the sawed-off nipples into your scrap brass bucket.  Be safe, and happy reloading!  For fun and extra credit (ha ha) lookup the price of empty 223Rem and 300BLK cartridges and see if you're making ‘money’ on each converted cartridge.