Home Forums Hunting & Shooting Ask The Gunwriters Full Length vs Neck Sizing

The first step was checking the necks for thickness variation. Close to 50% showed in excess of .002 with half of those being closer to .003. My normal cutoff is .0015 but I relaxed a bit on these cases as I knew I'd be touching up the necks with the neck turner.

When deburring the flash holes and lightly chamfering the flash hole from the inside, it became apparent that my chamfering tool (it uses an internal collar inside the case neck to pilot it) was only touching about half of the floor of the case. Long story short...the floor of these cases was 'tipped', for lack of a better term. My solution to that was to open the necks with a .338 expander and with the cases in a holder in the mill vise, I went in with a .312 end mill and squared up the 'floor' of the cases. The worse case took .016 to clean it completely so that's what I cut all of them to.

To neck them down to 6, they first went through a 308W seating die, then through a succession Redding Body Dies: 308W, 7-08, 260 Rem and 243W. I knew what the chamber neck length was from doing a CerroSafe cast and verified the end of the neck wasn't going to 'stack up' against the end of the neck area of the chamber, so I pushed the shoulders back with a standard 243W full length die (that I had shortened .075 based on the chamber cast). I just used a single case at that point and kept pushing the shoulder back in .005 increments until the action would j-u-s-t close with a skosh of resistance and set the die to that point.

They all then went through the shortened 243W full length die, the cases were trimmed to the same length, the necks were expanded over a .241 expander and the inside of the necks were cut with a .242 reamer to make them round and straight. Then they were neck turned with the .241 expander, neck/shoulder area was stress relieved at 450 for 15 seconds, washed in acetone, left to dry. Finally, they were full length sized again with a shortened 243W Type 'S' F.L. Bushing Die.

They were ready to rock at that point. After firing them all the first time to f-form them, the primer pockets were then uniformed.

Target was the first 3 shot group @ 100 yds. when fire forming. The shot at 11:30 is the fouler. I gave the scope two down and two right shot the little three shot 'weather report' .420 group....it actually measures quite a bit bigger than it looks. It shows a 9:00 pick up I missed on the flags. With f-formed cases, 5 shot groups at 100 are well under 1/2". Pretty decent for a falling block rifle with an oddball case, I think.

Hope this helps. -Al