After reading several posts here over the months, I have ordered a S-P Bullet Comparitor along with their Chamber Gauge. I 'm hoping this will allow me to remove some of the variables (at least in my own mind!) by taking measurements relative to the bullets ogive (sp?)rather than its point.

How can I best use this information when setting up my seating dies?? It seems to me
(& I maybe wrong!)that in an ideal world I should use a seating die which index's to the bullets ogive rather than one which rely's on a central post which pushes on the bullets "variable" tip whilst carrying out the seating operation. So are there any other
styles of seating die out there, or is this a
non issue??? I currently use a standard RCBS
"O" ring press and would prefer not to buy a new one at this point.

Pete

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Originally posted by Pete E:
After reading several posts here over the months, I have ordered a S-P Bullet Comparitor along with their Chamber Gauge. I 'm hoping this will allow me to remove some of the variables (at least in my own mind!) by taking measurements relative to the bullets ogive (sp?)rather than its point.

How can I best use this information when setting up my seating dies?? It seems to me
(& I maybe wrong!)that in an ideal world I should use a seating die which index's to the bullets ogive rather than one which rely's on a central post which pushes on the bullets "variable" tip whilst carrying out the seating operation. So are there any other
styles of seating die out there, or is this a
non issue??? I currently use a standard RCBS
"O" ring press and would prefer not to buy a new one at this point.

Pete

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Pete According to the type /style of bullet that you are loading many of the better type seaters use the ogive to press the bullet into the case, RCBS Comp.seater and Forster Ultra seater use a hollowed shaft that contacts the ogive or at least not the point of the bullet, check your seating stem and if you use a pointed bullet such as V Max check to see if the tip hits the seater shaft and if so you can drill it out alittle more and the shaft will contact the bullet on the area near the ogive, then use the SP setup to measure the seated depth and keep seating the bullet untill you get the match to your measurements of the rifle chamber and then lock the seater at this point, without a micrometer top it is trial and test to find the correct s/p match, good luck and good shooting!!

It took me a while to get consistent readings with my SP, and also with the RCBS Precision Mics before that. I do two things that help me get consistent seating depths. First is when measuring the bullet initially, I jam it hard into the lands. Enough so that I have to use a cleaning rod to push it back out. That gives greater consistency than just a gentle jamming of the bullet. The other thing I do is I build a dummy round with a bullet seated in a neck sized case which just touches the lands. To do this I seat it out about .010" to insure contact with the lands with the fired and sized case. I color the bullet with a Marksalot and chamber it and read the marks on the bullet. I color it again, and continue do this to seat it the approriate distance to just barely touch the lands. In this manner you can reset any die to zero after you start messing with seating depths and changing the die setting while developing loads.

There is a difference between the measurement using the unfired case you get from SP and a neck sized case fire formed in that chamber, which is why I double check the measurements as above to insure you know where off the lands your gun shoots best.