Cases Stretching
Quote from Reloader on July 7, 2012, 9:02 pmMy friend and I recently purchased a RL550b and have been loading ammo for a couple of months (.223 for AR15). We noticed that every now and then a case would not extract properly or get really stuck in the chamber. We started looking around for what could be causing the problem and we found out that during the resizing operation that our cases were stretching. We are trying to set our headspace to set the shoulder back about .004 but found out that when the expander ball comes up through the neck it seems to be pulling the shoulder out about .004 or so longer than the fired dimensions.
We use One Shot case lube on the outside of the case should we be hitting the inside of the case neck with it as well?
When examining the expander ball we also noticed that it seems to be a little off center of the mounting stem as well. Probably only about .002 or .003 off. Is that enough for it to cause the expander ball to stretch the case?
Thanks,
Jim
My friend and I recently purchased a RL550b and have been loading ammo for a couple of months (.223 for AR15). We noticed that every now and then a case would not extract properly or get really stuck in the chamber. We started looking around for what could be causing the problem and we found out that during the resizing operation that our cases were stretching. We are trying to set our headspace to set the shoulder back about .004 but found out that when the expander ball comes up through the neck it seems to be pulling the shoulder out about .004 or so longer than the fired dimensions.
We use One Shot case lube on the outside of the case should we be hitting the inside of the case neck with it as well?
When examining the expander ball we also noticed that it seems to be a little off center of the mounting stem as well. Probably only about .002 or .003 off. Is that enough for it to cause the expander ball to stretch the case?
Thanks,
Jim
Quote from Reloader on July 9, 2012, 3:01 pmAll bottleneck cartridges stretch during the firing/resizing process. No lube will prevent this. When the cartridge is fired, brass flows on the inside of the case from the base towards the neck. Resizing the case extrudes this brass, making the case longer. All bottleneck cases must be trimmed,typically every 2-3 firings. Trimming needs to be done after resizing.
All bottleneck cartridges stretch during the firing/resizing process. No lube will prevent this. When the cartridge is fired, brass flows on the inside of the case from the base towards the neck. Resizing the case extrudes this brass, making the case longer. All bottleneck cases must be trimmed,typically every 2-3 firings. Trimming needs to be done after resizing.
Quote from Reloader on August 31, 2012, 4:09 pmAs Dillon stated, bottleneck cartridges must be measured after re-sizing, and trimmed to spec dimension. I have also been checking straight wall brass after the second firing (M1 Carbine and .45 Colt) and found stretching past spec measurement in specific manufacturers. Again, size, de-prime and measure. Do not put a new primer in until trimming is done. If you use hand held Lee trimmers, the primer pocket has to be empty. A bench top lathe trimmer can work with a new primer inserted, but I personnaly do not want a live primer installed during this operation.
As Dillon stated, bottleneck cartridges must be measured after re-sizing, and trimmed to spec dimension. I have also been checking straight wall brass after the second firing (M1 Carbine and .45 Colt) and found stretching past spec measurement in specific manufacturers. Again, size, de-prime and measure. Do not put a new primer in until trimming is done. If you use hand held Lee trimmers, the primer pocket has to be empty. A bench top lathe trimmer can work with a new primer inserted, but I personnaly do not want a live primer installed during this operation.