LiveLife
Member
OK, let's cover some basics.Quick question, has anyone run into any issues not applying crimp to 9mm ammo?
First, most of neck tension comes from friction with case wall against bullet base further down the case neck towards the bottom of bullet base where the case wall is thicker. Here's a listing of case wall thickness .200" below case mouth - https://www.thehighroad.org/index.p...nd-bullet-setback.830072/page-3#post-10713822
Keep in mind that taper crimp is applied near the case mouth where the brass is thinner but this won't increase neck tension as much as friction from resized case wall further down the case neck from thicker case wall. Here's a listing of case wall thickness .100" below case mouth where taper crimp is applied - https://www.thehighroad.org/index.p...nd-bullet-setback.830072/page-3#post-10712225
This is why increasing the taper crimp won't increase neck tension.
And this myth busting thread tested the neck tension of various case wall thickness brass using NO TAPER CRIMP as flared case mouth was just returned flat on the bullet - https://www.thehighroad.org/index.p...neck-tension-and-bullet-setback.830072/page-4
So no, not using taper crimp is OK if you have sufficient neck tension from properly sizing the brass and using brass with thick enough case wall.
Besides, autoloading straight walled cases headspace on the chamber with case mouth and if too much taper crimp is applied, round won't headspace on the case mouth rather held by extractor.
And as many have posted, especially with plated bullets, using too much crimp will indent/cut into the plating (which may cause leading of barrel) and deform/reduce the bullet diameter and decrease neck tension that could cause bullet setback.
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