Decaping mandrels made easy.

[RBHarter]

I use a 7/16 grade 5 bolt for RCBS dies as it saves threading the rod but makes for a lot of cutting on smaller calibers. I cut the bolt head off w a hack saw in the drill press . And then set about cutting the bolt down to a more or less square line of the desired neck ID , leave it a little over size for finishing . For this part I use a 12 in double cut %@*&$ that cuts wide fast and rough. The next step is to smooth the whole thing down and shape the rod . For my uses I like to cut the point under .200 , this allows neck ups from 22 to whatever. A vital point to remember is to cut the shank portion smaller than the expander portion by a fair margin as the sizer takes the neck down a ways below the nominal dimension so in an 8 mm cut it to .300 or so. For the universal decapper I use smaller crs rod 30-31 cal get 5/16 down to 25 which I use 1/4 in bolts .

To get a decaping pin I run the mandrels down on to a 1/16 inch drill bit secured in the drill vise . I drill about a 1/2 in into the mandrels. This generally results in a centered pin hole that is straight. At this point I like to slick up the mandrel and polish the expander . Last step . I drill for a set screw . I've had good luck w/10-32 s and using the Allen type screws. The set screw is for the headless pins so they can be changed out. As far as tapping a through drill works best.

[Crumb Castle]

That is pretty slick!

[larryw]

Sweet.. That's very nice work RB.

[RBHarter]

It was needed for a 7.62x39 that has a 316x305 bbl I wanted to shoot cast in.

[scotland]

That is neat. Wish I had the talent and the equipment.