Originally Posted by Mikecr
The basis of my argument is that standard FL dies don't always match individual chambers. They often oversize (like the entire neck), and sometimes they counter bump with too much body(depending on chamber to die).
There are many posts here with one problem after another from FL sizing. Not so many from those who size only what they need.
Agree on that necks are often sized too much, that is why I recommend the bushing die or conversion as the go to die.
As to the "counter bump with too much body, not sure what you are referring to exactly.
if sizing the lower body, yes that can happen compared to optimal, but that will not lead to shoulder/case neck separation or other measurable negative accuracy effects in a "factory chamber and barrel". If talking shoulder bump, that is die adjustment and nothing else, which is the major problem people talk about.
as to all the posts on FL dies, 95% are due to improper adjustments!
I have more than several sets of die conversions from JLC and not one has experienced the issue you talk about not enough springback.
Plus if that is an issue, Jim should be able to see that right off when he measures them and tell you to by the small base body die from redding which would solve that problem. Plus that will not happen in a factory chamber as they tend to be on the large size if anything.
As to the basis that FL dies do not match, that same arguement applies for NS only. Absolutely no different other than using a NS bushing die being able to control the neck, which is only one part of the chamber and brass dimensions.
My point in reality is why try to buy a standard die (NS or FL) IF max accuracy is key even in a factory chamber. Go for a custom honed bushing die and control ALL aspects of the brasss. Not just the neck and it can be done for $100.
Beats trying to keep track of how many firings and sorting cases into 4 or more batches and running each loaded round thru the gun to see if it chambers.