Poper
Member
I've been loading my own ammo for going on 30 years now. However, I still occasionally learn something here and there.
Many years ago, a good friend of mine (now deceased) gave me a Stoney Point Bullet Comparator for Christmas. I have never used it until tonight because I prefer the RCBS Precision Mic for setting my seating depth in relation to the bullet ogive and for setting the sizing die to precisely set the fired case shoulder back .002".
I discovered tonight that even an Old Dog really can learn something new.
I was perusing my Berger Bullets manual for appropriate .30-06 loads using the 168 grain VLD and inadvertently slipped and ended up back toward the front of the manual and into the section titled "Effects of Cartridge Overall Length (COAL) and Cartridge Base to Ogive (CBTO)". I am not sure exactly what it was that caught my eye and started me reading the section, but after doing so, I now understand why even after carefully sorting bullets by weight and diameter and seating with an RCBS competition die, I would still often get variances greater than .015" when measuring the loaded rounds with a Precision Mic. It also explains why a couple years ago I got significantly better groups from a batch of .308's I had loaded and seated the bullets painstakingly, and singly, to within .001" when measured to the ogive with the Precision Mic. It was really labor intensive, but the difference in the groups was very significant.
Back to the Stoney Point Bullet Comparator... After reading in the Berger manual that the precise location of the bullet ogive in relation to the base of the bullet often varies as much as .025", and sometime more, and that this dimension can be accurately measured with the Hornady (formerly Stoney Point) Bullet Comparator, I dug out the unopened one Russell gave me so many years ago. Within a few minutes I was measuring bullets and confirming exactly what the Berger manual said.
Moral to the story: The Precision Mic is a great tool to set your sizing die, set your seating die and to check your CBTO length. However, it is necessary to measure and sort bullets for the precise location of the bullet ogive in relation to the bullets' length to be able to precisely set the ogive in the same CBTO length which automatically provides a consistent throat-jump dimension which is, as we all know, essential for maximum accuracy performance with our gun-specific tailored loads.
Sorry so long. I kind of got caught up in the "AH-HA!" of the concept and I wanted to share it.
Poper
Many years ago, a good friend of mine (now deceased) gave me a Stoney Point Bullet Comparator for Christmas. I have never used it until tonight because I prefer the RCBS Precision Mic for setting my seating depth in relation to the bullet ogive and for setting the sizing die to precisely set the fired case shoulder back .002".
I discovered tonight that even an Old Dog really can learn something new.
I was perusing my Berger Bullets manual for appropriate .30-06 loads using the 168 grain VLD and inadvertently slipped and ended up back toward the front of the manual and into the section titled "Effects of Cartridge Overall Length (COAL) and Cartridge Base to Ogive (CBTO)". I am not sure exactly what it was that caught my eye and started me reading the section, but after doing so, I now understand why even after carefully sorting bullets by weight and diameter and seating with an RCBS competition die, I would still often get variances greater than .015" when measuring the loaded rounds with a Precision Mic. It also explains why a couple years ago I got significantly better groups from a batch of .308's I had loaded and seated the bullets painstakingly, and singly, to within .001" when measured to the ogive with the Precision Mic. It was really labor intensive, but the difference in the groups was very significant.
Back to the Stoney Point Bullet Comparator... After reading in the Berger manual that the precise location of the bullet ogive in relation to the base of the bullet often varies as much as .025", and sometime more, and that this dimension can be accurately measured with the Hornady (formerly Stoney Point) Bullet Comparator, I dug out the unopened one Russell gave me so many years ago. Within a few minutes I was measuring bullets and confirming exactly what the Berger manual said.
Moral to the story: The Precision Mic is a great tool to set your sizing die, set your seating die and to check your CBTO length. However, it is necessary to measure and sort bullets for the precise location of the bullet ogive in relation to the bullets' length to be able to precisely set the ogive in the same CBTO length which automatically provides a consistent throat-jump dimension which is, as we all know, essential for maximum accuracy performance with our gun-specific tailored loads.
Sorry so long. I kind of got caught up in the "AH-HA!" of the concept and I wanted to share it.
Poper
lol , I've been using my old Starrett tools and a reading off the ogive for years , but I bit my lip and said nothing , as I'm a young man of only 44 years , and only been handloading for 16 years , glade to see I have been doing it right , lol.. I use to do it with a bushing and a dial indicator , a few year back I bought the Hornady Comparator , much faster, Glad to see I need not change my ways (well with bullet seating anyhow 
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