Just saw the sticky on this and it helps a lot. I measured 39 Hornady 162 Amax and the ogive length difference of 0.011" using a Sinclair Nut (7mm hole) and dial caliper. Is this a lot of variance? Is this the same measurement (bearing surface) as described in the article using the inserts on a dial caliper? I will measure another 400 bullets if this is a proper technique, but if not, someone please tell me. If not, I will get the right equipment to do it. Thanks. Ron.
Sorting bullets ?
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Guess I will have to upgrade from my old Sinclair Hex Nut. Seems there are many devises to do this. Assuming my measurements are close to correct, does anyone know if 0.011" is way much? I noticed green and yellow box were not bad. No mention of red box. Does that mean what I think it does. Thanks. Ron.
The word ogive has different meanings to different people, that's part of the problem. Yes is the answer, but not the whole answer. There are some good articles by B Litz available on his site (Applied Ballistics) that illuminate "ogive" pretty well. I would add that the sloppy use of language by all of us helps to confuse the issue. Read this. Below is part of a post from another thread that's pretty good too.
While I think technically the ogive is the area from the main body diameter to the tip, functionally most people that I know use the term 'ogive' to refer the point where the body diameter transitions to the curve of the nose. Sometimes there is a bit of confusion as the 'ogive' diameter in that sense is markedly different from the 'ogive' diameter where the typical bullet seater makes contact. Bearing surface is the distance from where the body gives way to the ogive at the front of the bullet to where the body transitions to the boat tail at the rear - i.e. the portion that is actually in contact with the rifling. Think I got most of that reasonably correct
I found this thread doing a search for acceptable SD for shank length (bearing surface). I sorted 1K a-max and found a very narrow bell curve distribution, but was surprised that 2 SD each side of mean was .630 - .640. These were sold as "seconds" which is why I bothered to sort them at all, but a hundredth between top and bottom is the same % as a 2 gr spread in 140gr class bullet weight! Seemed like a lot.
I would love to find a way to easily measure the consistency of the ogive shape bullet to bullet.
'Easily' would cost $$$... as in purchasing a tool-room grade optical comparator (never used one, but supposedly they are the correct tool for this sort of thing) and hiring someone else to measure and compare each boolit. I'm guessing return-on-investment would be poor, though 
In a somewhat more serious vein... I had thought that perhaps something like this would be a good use for something like a Raspberry Pi, using some of the gpio pins to control a small motor to slowly spin the bullet and then perhaps some software like SimpleCV to take images polled from a USB microscope and comparing the dimensions via a program written in Python, and have it display the results on a small local web server... sadly its one of those things that I know enough about to have the idea, but not enough to actually carry thru with myself at this point.
In a somewhat more serious vein... I had thought that perhaps something like this would be a good use for something like a Raspberry Pi, using some of the gpio pins to control a small motor to slowly spin the bullet and then perhaps some software like SimpleCV to take images polled from a USB microscope and comparing the dimensions via a program written in Python, and have it display the results on a small local web server... sadly its one of those things that I know enough about to have the idea, but not enough to actually carry thru with myself at this point.
I'll bring the beer, make snide comments and stand around while you puzzle through it if you want to team up on the project. Sounds like a cool process.
I found as much as .027" difference between ogive to base on my Hornady 168 gr A-Max. It caused some serious accuracy problems for me but once I got it figured out I haven't had any more problems. This is a link to the 308 forum I belong to and you can see what I had to do to rectify the problem.
Need advice ? - Reloading - 308AR.com Community
Need advice ? - Reloading - 308AR.com Community
