Cy Soto Posted April 22, 2009 Share Posted April 22, 2009 Will over-crimping a case significantly increase the case pressure? Thanks! Link to comment Share on other sites More sharing options...
bompa Posted April 23, 2009 Share Posted April 23, 2009 Too much taper crimp might leave you with a loose bullet that will set back while feeding.. Set back causes higher pressures thus maybe big problems.. Crimp only enough to remove the flair,bell,case tension should hold bullet securely during feeding.. On a revolver case a heavy roll crimp might be called for but not on an auto case.. Link to comment Share on other sites More sharing options...
mecury Posted April 23, 2009 Share Posted April 23, 2009 As far as Isaac Newton is concerned.............YES Link to comment Share on other sites More sharing options...
Steve J Posted April 23, 2009 Share Posted April 23, 2009 Too much taper crimp might leave you with a loose bullet that will set back while feeding.. ?? Seems to me the tighter the taper crimp the more secure the bullet and the lesser the chance of bullet set back. How is the opposite possible? I can't wrap my head around that one. Link to comment Share on other sites More sharing options...
bompa Posted April 23, 2009 Share Posted April 23, 2009 To much taper crimp will resize the bullet and the case,the brass case will have some spring back where as the lead core of the bullet has none.. Thus you have a loose bullet.. Try it with a unprimed case,why waste a primer and powder,and see what happens..Do the bullet test,press the round against the bench and check for set back.. Link to comment Share on other sites More sharing options...
G-ManBart Posted April 23, 2009 Share Posted April 23, 2009 Not so much in auto ammo. In revolver ammo where you're crimping into a cannelure it would make more difference, but it's still a slight change. Neck tension (technically "bullet pull") should be determined by how much the case gets resized and the diameter of the bullet more than anything. Pick a target diameter for your crimp, set it and leave it there. For .40 and 10mm .420" seems to work perfectly in pretty much any gun. Go bigger and it'll hang up in some guns and smaller will start to cut into bullet jackets, or allow the bullet to seat too deeply. For 9mm, 38 Super/SC something around .378-380" should work fine. For .45acp you'll want something around .468-470" should work fine. Link to comment Share on other sites More sharing options...
Steve J Posted April 23, 2009 Share Posted April 23, 2009 To much taper crimp will resize the bullet and the case,the brass case will have some spring back where as the lead core of the bullet has none..Thus you have a loose bullet.. Try it with a unprimed case,why waste a primer and powder,and see what happens..Do the bullet test,press the round against the bench and check for set back.. :lightbulb: ahh. Lee even says that their FTCD will size the bullet. I load Zero FMJs so it's not really an issue for me. Link to comment Share on other sites More sharing options...
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