Here is an un-scientific experiment:
My 44 die set (carbide resizer) has the expander stem polished down to the point that loaded rounds are "wasp waisted" so as to provide plenty of neck tension. I loaded three lubed Keith 250 gr. cast bullets in unprimed empty cases without applying any crimp. Inserted into an inertia bullet puller and gave it several healthy whacks on my block of 2x4 used for this purpose. All three bullets pulled enough by the third "whack" to have tied up the cylinder on my Smith.
I selected three more pieces of brass of the same brand, seated lubed bullets but this time with a heavy roll crimp. After the third whack on the 2x4, there was no noticeable movement of the bullet. I tried to make the "whacks" equal (I told you it was un-scientific) and added two more whacks each on the crimped cartridges. At this point, the bullet had moved slightly, but still not enough to tie up the cylinder of my Smith.
Why crimp? This is my answer........ Have a nice Easter Sunday.
