A friend has a brand new Ruger Mark II varmit rig in .22/250. He reloads on a Dillon Press. Marty came by a few minutes ago with some cases. On several of them the primers backed out, not all the way, mind you, just about one-thirtysecond of an inch.The load is not hot, right at 34 grains of AA 2520. Anyone out there have any explains why the primers might be backing out of this round. The bullet is seated to .01 inch off the lands. Thanks for any replies ... Tom Purdom

Too much headspace in the brass. He is oversizing the cases and setting the shoulders back too far.

It may be a combination of headspace, as Bob338 said, and a light load. There is enough pressure to push the primer back against the bolt face but not force the case back. Try raising the powder charge .5 grains at a step until the case comes out with the primer flush. Adjustthe sizer die so that it just touches the case shoulder on a fired case that rechambers easily. You can do this by smoking the case shoulder with soot from a match or candle and adjusting the die down until it just contacts the shoulder, or use the RCBS headspace gauge or the Stony Point tool. If you don't set the shoulder back more than about .002" you should get good case life and reliable chambering.

These guys got it right--believe em'!!

Your chamber may need to be polished. If it is ruff it will keep case from sliding back.

wrong conclusion roundbutttt,
if the case did not have the shoulder pushed back toooo far during resizing, it goes nowhere during firing....your comment will have the heads of the cases moving backward to contact the breech face while the sidewalls are remaining stationary during the combustion/expansion milliseconds. This leads to case head seperations after three to 6 firings.....what a waste of good brass.

ShondorP

[ 12-23-2002, 04:21: Message edited by: ShondorP ]

This happens even with fire-formed cases.I would increase my charge if this is happening to many rounds.Sometimes it happens to the first two or three and then stops when the barrel heats up.It can happen many times in freezing temperatures.Again,if you don't want this to happen increase your charge.