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Rifles, Reloading, Optics, Equipment
Reloading
300WM - Factory ammo "overpressure" signs
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<blockquote data-quote="SMK1000plus" data-source="post: 1956198" data-attributes="member: 93846"><p>It seems your Hornady factory load brass is @ 0.18" (18 thousandths) under your datum measurement of your once-fired brass. Your once-fired brass datum is right-on for the SAMMI spec of 2.276" (2.196" to shoulder/body junction, plus 2.356" to shoulder/neck junction, equals 4.522", then ÷ 2 equals 2.276" to center/datum).</p><p></p><p>0.018" is a LOT of case stretch! Most of my 300 Win Mag. factory ammunition runs @ 0.004 to 0.006" under to the 2.276" datum of my once fired brass. It makes sense that it would show up just in front of the case belt, as the belt is actually setting the headspace and holds the case head end relatively stationary. The brass must flow forward to reach the chamber shoulder and the powder column would cause the brass to stretch behind it, that micro-second of initial ignition.</p><p></p><p>Try another Lot# ammunition or a different brand.</p></blockquote><p></p>
[QUOTE="SMK1000plus, post: 1956198, member: 93846"] It seems your Hornady factory load brass is @ 0.18" (18 thousandths) under your datum measurement of your once-fired brass. Your once-fired brass datum is right-on for the SAMMI spec of 2.276" (2.196" to shoulder/body junction, plus 2.356" to shoulder/neck junction, equals 4.522", then ÷ 2 equals 2.276" to center/datum). 0.018" is a LOT of case stretch! Most of my 300 Win Mag. factory ammunition runs @ 0.004 to 0.006" under to the 2.276" datum of my once fired brass. It makes sense that it would show up just in front of the case belt, as the belt is actually setting the headspace and holds the case head end relatively stationary. The brass must flow forward to reach the chamber shoulder and the powder column would cause the brass to stretch behind it, that micro-second of initial ignition. Try another Lot# ammunition or a different brand. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Reloading
300WM - Factory ammo "overpressure" signs
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