Case length and resizing

[Pieter C. Voss]

I have about 300 30-06 cases for my '03 Springfield with which I shoot one or two 200 yd. highpower matches a month plus weekly practice sessions of 50-70 shots. I necksize with a Lee collet die and expand with a tapered drift which has a line engraved around it at the point where it enlarges the case mouths to about .312. I was using a Lyman M die but thought I might be working the brass a bit much so have lately adopted this method. Also this results in a tighter grip on the bullet. All my brass was trimmed when new to 2.482 for uniformity but when I recently measured them a good number have shortened to about 2.475. These were resized with a Redding body die but any increase in length was negligible, maybe a thousandth or two. My loads are mild--the Ed Harris load of 16g 2400 behind the SAECO 315 or Lyman 314299 sized .311. I guess I have a couple of questions; Where did the brass go? and Would it be worthwhile to sort brass by length? I have separated the short ones but now am wondering if the rest of the lot should be sorted by length. Pete

[uscra112]

One of the curses of light loads in the .30-06. Mild loads in cases which headspace on the shoulder are notorious for having that shoulder move back. What happens is that the primer explosion drives the case forward in the chamber, but the powder burn does not create enough pressure to shove it back again. Check all your cases, using a gage that measures length to the shoulder. (a Wilson case length gage is a necessary part of .30-06 reloader's kit. Midway has them.) Do it soon. Because the shoulder is pushed back, you have a headspace problem. You may also observe the primers protruding from their pockets after firing shortened cases. Do not under any circumstances fire those cases with full loads. A dangerous case separation just forward of the head is likely to occur. Such excitement you can do without.

The brass hasn't disappeared. The reason you're seeing the OAL reduced is that the neck is being carried back along with the shoulder.

I have on occasion rectified such cases by lubing them with lanolin (case lube) and firing a very reduced load. The case will slide back in the chamber easily and the shoulder will be blown forward again. The chamber must be then completely cleared of the lube before firing any heavier loads! With the lube in there, the case does not grip the chamber walls, and the bolt thrust becomes enormous at full-load pressures. Rifles have been blown up by this ! This is why I use lanolin based case lube - it is easily and completely removed with warm water.

One way to reduce the shortening of the cases is to drill out the flash holes to about .085". But cases so modified must never ever be used with full loads.

My own permanent solution is to use a rimmed cartridge when I want to shoot light loads, and not the -06.

[Pieter C. Voss]

ucra--thanks for the reply. I should have said that I checked the short cases with a Wilson case length gage and no shoulder setback is indicated. It occurs to me that possibly variations in case wall thickness might account for the shorter cases. In that case, I ought to weigh cases and see if the lightest are shortest, or maybe the heaviest. Shifting gears somewhat, I do want to shoot some matches with a rimmed cartridge, namely the 303 Brit. in a nice SMLE No.4 MK I . The clubs where I shoot have occasional vintage military matches. Pete