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What squad am I on?
TriStar TT-15 Combo
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“Choot em”

I’ll get a few like that now and then. Every time I see one I kinda wonder what causes it but after a while you’ll chuck a hull in the press and know it’s gonna do it.
 

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Premium Member
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6,614 Posts
Which part of the crimp are you referring to? The fact the crimp depth may be too deep? Or the fact the petal folds are sphinctered? The former might give me pause because crimp depth has an impact on chamber pressure. If the latter? Shoot 'em.
 

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The petal folds.
I would pay more attention to the crimp depth. Yours look too deep. Here is what Hodgdon says about the impact of crimp depth on pressure:

Crimp Depth Velocity Chamber Pressure
0.030″ (too loose) 1,308 fps 9,300 psi
0.050″ (normal reload crimp) 1,329 fps 10,500 psi
0.070″ (too tight) 1,351 fps 11,900 psi
0.090″ (very tight crimp) 1,363 fps 13,100 psi
 

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Crimp Depth Velocity Chamber Pressure
0.030″ (too loose) 1,308 fps 9,300 psi
0.050″ (normal reload crimp) 1,329 fps 10,500 psi
0.070″ (too tight) 1,351 fps 11,900 psi
0.090″ (very tight crimp) 1,363 fps 13,100 psi
Wow, what do you know. A direct relationship between pressure and velocity !

Nebs - any chance Hodgdon mentioned what hulls they used for this test data ? Just a hunch, but I bet there is some variation in the hulls these days regarding how well they can resist "opening up" upon ignition. The more they resist, the higher the pressure can go. Like - I would say Gun Clubs might be at the higher end of resistance, and paper hulls or some of the very flimsy cheapo hulls at the lower end of resistance.
 
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