So let the die touch the shell holder when I FL resize for max feeding reliability?
No, buy case gages, like this Wilson type, and using the gages, see just how far the shoulder has moved. Then push the shoulder back about 0.003"
I have a 80's vintage Marlin 336 that has a huge chamber.
The shoulder was cut so deep that the rim of a fired cartridge almost hangs out of the case gage. The extra volume created by this huge chamber is such I am 2 grains over maximum loads recommended by reloading manuals, to get 2150 fps with a 170 grain bullet.
These are my two best loads at 100 yards, and they are over the maximum in reloading manuals.
Full length resizing cases that come out of a chamber like this will simply cause case separations in short order. In this rifle, I slathered new cases with sizing lube, or paste wax, so the case would not grip the chamber walls on the first firing. Once the case was fire formed to the chamber, and the shoulder only set 0.003" back, the risk of case breakage due to excessive shoulder to base headspace was eliminated.
I also cannot set the bullet deep enough to touch the lands. Tried that as an experiment using a 170 grain bullet. The bullet was barely inside the case mouth, I inserted it into the chamber, and was expecting the throat to soft seat the bullet. Instead, no bullet set back at all. The combined length of case and bullet was so long that it would not eject from the loading port and I had to remove the lever, and then the bolt, to get the cartridge out. After examining the bullet and finding no marks, I concluded the throat was way the heck up the barrel. Then on, I simply seated to the bullet cannelure.
I am of the opinion that Marlin used a new reamer in my rifle, a reamer so large they could cut a lot of chambers before it wore out.