JGFLHunter

Ok I'll try to explain better in different way in different sections.
All cases were trimmed the same length and made to same overall length
example - trimmed to 1.672" total length - 2.260"

1. Whenever you shoot ammo, shouldn't the case expand and become longer then previously before firing? But to answer your question, after firing my ammo I wanted to see if the cases were longer in length. Most cases were actually shorter than what they were before being shot. I hope that's clear. Are cases supposed to be shorter after they have been shot? So like in example, the case length before was 1.672" and after being fired was 1.670". Shouldn't the case be longer?
Different subject
2. I was testing crimp and non crimp bullets from magazine to chamber, without firing to see what actually happens to the total overall length of the ammo. I found that without a crimp on the ammo, in my AR, the total overall length increases between .007-.010". So like example the 2.260" would actually end up being 2.267" etc.
The ammo that had a crimp using the FCD instructions (maximum crimp I believe) the total overall length of ammo was .002" longer. Are there any good videos to actually see how to crimp and how to do it properly? Is that heavy a crimp safe to use?
3. The bullets do not get set back but actually are being pushed forward (even with heavy crimp as stated above) Is that a huge deal in terms of accuracy and performance in general?
Different subject
4. How do I set the die to the deminsions from a fired cartridge? I did measure inside the mouth(fired cartridge) and after running through the FL die to compare the to, the mouth or neck (where you seat bullet) was actually smaller (.007") than the fired case.

I really hope this makes sense, I'm trying to explain it best I can. Thanks for the patience