@brokenanew - Thank you for also confirming this. I'm still learning how to set my seating die correctly and crimp. For now I'm just messing with empty rounds and continuing my reading.
First thing if not mentioned is getting a reloading manual. I use the Lymans 49th. They have all case specs.
I do have a manual. I picked up Hornady's 8th Edition Reloading Handbook
I have a Smith & Wesson M&P15. I have swapped out the stock 16" barrel for a BCM Standard 14.5" Mid Length Barrel
along with a few other cosmetic changes.
This is an oft repeated myth based on hearsay, and conjecture, that has in fact, been debunked in this thread and others - see my post on this topic. While this is true for 308, it is NOT true for 223 - LC are not materially and consistently any less volume than commercial. In fact the opposite may be true in many cases: see the chart and look for LC06 - they held the most.
As some one else said, "Be wary of those who want to tell you what they think they know. They may NOT."
And we use English language spelling here, not texting-child phonics.
@Marco Califo - thanks for setting that strait