9mm data question

skizzums · January 24, 2015, 06:01 PM

loading up some 9mm 90gr. sierra jhp. weird data. I am using titegroup, current hodgdon manual

80gr TAC-XP 3.0gr-3.6gr 32,9kpsi
90gr GD 4.7gr-5.0gr 30kCUP
95gr sie same as above

why would the tac-xp take a lighter charge at a lower weight equaling a higher pressure? how can the bullet be that different to take a 20% lower charge on a 10% lighter bullet. obviously, I think I should just stick with the 90gr data, since the tac-xp is an all copper bullet, but I am just wondering why the copper bullet makes THAT significant of a difference when oal is within .01 of each other

someone school me on copper bullets please......

noylj · January 24, 2015, 09:23 PM

TAC-XP is a monolithic copper bullet that increases pressure quite rapidly, so data has to be much lower for the same pressure. Added to that, the monolithic bullets, for a given weight, have to be much longer--thus increasing pressure more.
ONLY use jacketed lead-core data for jacketed lead-core bullets and only use monolithic data for monolithic bullets.

January 24, 2015, 06:01 PM	#1
skizzums Senior Member Join Date: July 1, 2013 Location: Douglasville, Ga Posts: 4,615	9mm data question loading up some 9mm 90gr. sierra jhp. weird data. I am using titegroup, current hodgdon manual 80gr TAC-XP 3.0gr-3.6gr 32,9kpsi 90gr GD 4.7gr-5.0gr 30kCUP 95gr sie same as above why would the tac-xp take a lighter charge at a lower weight equaling a higher pressure? how can the bullet be that different to take a 20% lower charge on a 10% lighter bullet. obviously, I think I should just stick with the 90gr data, since the tac-xp is an all copper bullet, but I am just wondering why the copper bullet makes THAT significant of a difference when oal is within .01 of each other someone school me on copper bullets please...... __________________ My head is bloody, but unbowed

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January 24, 2015, 09:23 PM	#2
noylj Senior Member Join Date: October 21, 2007 Location: Between CA and NM Posts: 858	TAC-XP is a monolithic copper bullet that increases pressure quite rapidly, so data has to be much lower for the same pressure. Added to that, the monolithic bullets, for a given weight, have to be much longer--thus increasing pressure more. ONLY use jacketed lead-core data for jacketed lead-core bullets and only use monolithic data for monolithic bullets.