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Posted: 1/30/2016 12:25:24 PM EDT
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From what I can see it looks like the Winchester brass had too much crimp on the bullet.
It is common for really old brass and brass that has been reloaded many times to develop split necks. If this ammo was purchased new recently from a store you might contact Winchester and send them some fired brass in the original box that contains the lot number. If it's reloaded by you or someone else it's obviously toast. The amount of crimp on the case mouth is more than I have ever seen before. BTW - I never crimp bullets except for magnum pistols or lever action rifles. .0025" to .003" neck tension is plenty to hold a bullets securely in the case. |
The bullet crimping is a touch over the top, but being that this is M855 that is not intended to be reloaded anyways, may not get any resolve out of win for it cracking the necks at the deeper crimps on the first firing instead.
LC M855 and the bullet crimps are not as severe instead. 
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Don't know if it's what you have, but Winchester has a recall on some of their M855
http://www.winchester.com/library/news/Pages/product-recall-556mm-m855.aspx CY6 Greg Sullivan "Sully" SLR15 Rifles TheDefensiveEdge.com (763) 712-0123 |
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