The Firing Line Forums - View Single Post - 40 Cal Taper crimp doesn't work on 135 gr Nosler HP??

drail · August 10, 2012, 06:16 PM

Bullet dia. and expanded case dia. are the problem. The case is either overexpanded or the bullet is under dia. No type of crimp will hold the bullet in the case. The case's neck tension is what holds it. Measure the expander button from your die and measure the bullet. If the expander button is not at least 4 or 5 thous. smaller than the bullet it is not going to allow enough case neck tension. The crimp serves ONLY to remove the flare from the case, that's all it does. I would almost bet that your previous loadings with those dies were allowing some bullet movement as well. But check the dia. of the new bullets first. Every set of pistol dies I have ever owned had an expander button that was oversized. I have turned them down to slightly less than bullet dia. in a drill press. They won't pull or setback now. Variations in case wall thickness can result in insufficient neck tension also. Some brands of brass are thinner than normal.

August 10, 2012, 06:16 PM	#2
drail Junior member Join Date: February 2, 2008 Posts: 3,150	Bullet dia. and expanded case dia. are the problem. The case is either overexpanded or the bullet is under dia. No type of crimp will hold the bullet in the case. The case's neck tension is what holds it. Measure the expander button from your die and measure the bullet. If the expander button is not at least 4 or 5 thous. smaller than the bullet it is not going to allow enough case neck tension. The crimp serves ONLY to remove the flare from the case, that's all it does. I would almost bet that your previous loadings with those dies were allowing some bullet movement as well. But check the dia. of the new bullets first. Every set of pistol dies I have ever owned had an expander button that was oversized. I have turned them down to slightly less than bullet dia. in a drill press. They won't pull or setback now. Variations in case wall thickness can result in insufficient neck tension also. Some brands of brass are thinner than normal. Last edited by drail; August 10, 2012 at 06:22 PM.