603,
I have a Redding FL sizer too. I don't use it however as it squeezes the neck to much, and when the expander ball is dragged back out it expands the neck too much. The cases end up with an OD of .2895-.2900". As we know the OD of a loaded bullet is .2900-.2905, so that means the bullet grip is only .0005. Fine for a bolt gun, but not a lot for an auto-loader.
[ATTACH=CONFIG]19914[/ATTACH]
If your sizer is squeezing the neck the same as my Redding to .2780 (no stem), and after seating and fired expands to .300, that is a lot of stretch. But the splits could be from an unsupported neck at time of firing.
55,
If 603 measures his spent cases at .300 then that is plenty of room in the chamber to release the bullet. But...if his Redding is like mine and only holds the bullet by .0005 of neck tension then the bullet is able to move when slammed into a semi auto and comes to a sudden stop. The bullet moves forward with inertia and jams into the lands. As we know with throat jammed bullets there is a spike in pressure at firing. With 603's generous .300 chamber the case at the neck is unsupported at the time of the pressure spike. The unsupported necks split. If the case neck is properly expanded and sealed/supported against the chamber wall then there is no reason for the split.
The Forster without the expander ball squeezes the case neck to .286. The bullet goes in and it is now .290 = .004 of neck grip. That's why I prefer the Forster to Redding - it works the brass less, and grips the bullet more.
I have a Redding FL sizer too. I don't use it however as it squeezes the neck to much, and when the expander ball is dragged back out it expands the neck too much. The cases end up with an OD of .2895-.2900". As we know the OD of a loaded bullet is .2900-.2905, so that means the bullet grip is only .0005. Fine for a bolt gun, but not a lot for an auto-loader.
[ATTACH=CONFIG]19914[/ATTACH]
If your sizer is squeezing the neck the same as my Redding to .2780 (no stem), and after seating and fired expands to .300, that is a lot of stretch. But the splits could be from an unsupported neck at time of firing.
55,
If 603 measures his spent cases at .300 then that is plenty of room in the chamber to release the bullet. But...if his Redding is like mine and only holds the bullet by .0005 of neck tension then the bullet is able to move when slammed into a semi auto and comes to a sudden stop. The bullet moves forward with inertia and jams into the lands. As we know with throat jammed bullets there is a spike in pressure at firing. With 603's generous .300 chamber the case at the neck is unsupported at the time of the pressure spike. The unsupported necks split. If the case neck is properly expanded and sealed/supported against the chamber wall then there is no reason for the split.
The Forster without the expander ball squeezes the case neck to .286. The bullet goes in and it is now .290 = .004 of neck grip. That's why I prefer the Forster to Redding - it works the brass less, and grips the bullet more.