Steve4102,,There is some truth to those tests for sure but not in all situations.I usually seat .005 off the lands for long range ammo and I have tried as far as .025 off the lands Both with accuracy and no crimping.I also tried jamming into the lands and didn't see any accuracy loss or over pressure either( it was a lighter powder charge though!!)I have used full length lee pacesetter dies @625yrds with surprisingly excellent accuracy and I have also used my collet die( while checking shoulder displacement with a mic)with great accuracy..I would not be a bit surprised to not lose accuracy by using the collet die,and maybe even gain a little(but I dought it
).I was very surprised when I used regular LC brass full length sized,23.8gr of H4895,winchester primers and seated them to magazine feed length and gotten great accuracy..No special case prep and I used a cheap lee perfect powder measure for charging the brass..I have shot at least 100rnds @ 600yrds with under M.O.A. accuracy,One 5 shot group was near 3 inches..Its the combination and consistency that is bringing it together IMO..I think the ar design and Sandbags diserve most of the credit along with a great cartridge,, The 223,Oh im sure those awesome 77gr SMK coasters have something to do with it as well>