In .270 win. I had 5 Winchester brass, 5 Winchester plated and 5 Remington brass. All 1x fired range brass. These 5 plated were just in with the bunch, usely I have just brass on hand. All got possessed the same and fired through my .270 bolt action. After firing I found the brass in each brand needed to be trimmed as expected but the plated cases didn't budge, not at all, JUST the same length as I trimmed them to before loading. How come ? Obviously I don't load plated, will plated always behave that way ?