of a virgin Remington .222 Mag casing, then partially neck sized with the .224 donut, then a fire formed casing and a Hornady .204 Ruger casing for comparison.



You cannot just run a .222 Mag casing up into a .204 Ruger die. You must do as Mark suggested above and size to the .204 size a tiny bit at a time, making sure you stop when you can close the bolt with a high degree of difficulty. The shoulder of the .204 Ruger is pushed out toward the mouth of the case, the shoulder is 30� instead of 23� and the result is a much shorter neck with a larger case capacity.



I adjusted my full-length die so it would size just a small portion of the top of the .222 Mag case neck. The object here is to be able to get a crush fit with the .224 portion of the casing making it somewhat difficult to close the bolt. That pushes the casing head back into the bolt and eliminates any headspace problems. You don't have to seat the bullet so it jams into the lands this way. Just make sure you have a crush fit. With the right load of powder you will get a perfectly formed .204 Ruger casing when done.







I was seating 40 gr. V-Max bullets so they were .005 to .006" into the lands initially, but with the crush fit that is not necessary IMHO. I now use 32 gr. V-Max bullets, seat them far from the lands, and they are accurate enough so I can go prairie dog shooting with them if I don't try to make any 250 to 300 yard shots.

Hey GHD and Sliverfox,

Would you mind letting me know how you fire form .222 mag brass for .204's? Do you just neck down to .20 at the right length to headspace correctly and fire form? Thanks in advance.

Doc RD

That is basically it. I made a die for my 20 Tactical but if I only had factory dies I'd keep turning it down until the bolt would just close. I use 25 grains of 748 with a 32 gr Vmax for a chrono'd 3700 fps. I haven't done much load development with the formed cases yet.