Can anybody tell me if there are tools, where you can measure the Ogive from a bullet with?
So, I have a bullet and want to know which ogive it has?
There I need a tool for...
Hope somebody can help me out?
Without spending a fortune, I would get as close as possible with a digital camera, crop, enlarge, print and compare with drawn overlays or templates.
Here's how I have it
Bullet die makers decided they needed a term to verbally reference bullet shape. The thinker in the crowd came up with "ogive" and the resultant definition. Everyone was happy for a while...until an industrious individual figured out a some method to dispute the "exactness" of a particular claim concerning the ogive of a bullet. That sent the thinker back to the drawing board and he returned with the additional terms "secant" and "tangent". Currently, a die maker makes a bullet in his finished die, holds it up to the light and declares the ogive. Based on the manner in which the curved part meets the straight part he may or may not add the additional term - but will in all cases if pressed.
This terminology and its use has satisfied the consumer for all this time....until now. We all knew it was sure to happen just didn't know when.
I have measured ogives and shoulder angles using a digital photo print out. As Boyd said, enlarge it several times the original size, draw a center line, and then establish a measurement ratio using a caliper. Then use a drafting compass to try different ogive diameters until you hit the one that comes the closest.
An 8th grade geometry student can do it. Something much harder is trying to figure out Wilbur's post.
Theres an ogive chart in hatchers note book. you hold the bullet to the chart and you can see what ogive you have.
I kinda like Wilbur's post,
Actually, I like all of Wilbur's posts,
Bullet die making is an Art, it is not an exact science. The bullet your die produces is subject to many variables, not just the cavity of the point die. From a consumer standpoint, the finished bullet you recieve from you bullet maker is an individual entity,the exact description of it's ogive will not aid you in discovering it's accuracy potential or seating depth/load preference. It's accuracy potential is subject to your reloading finesse/experience-- Art ? If you are a one powder, one neck tension,one seating depth kind of reloader you may never experience your bullets full potential.
p.s. Trasch,if you are trying to duplicate a bullet that you have,you can send a couple to Brian Niemi or other die makers and they can get a new die close, but chances are it won't be an exact duplicate. Best bet would be to cut Brian Niemi or David Detsch or George Ulrich loose and request a good shootin' set of bullet dies for your application ( 100-200 br,etc.) These guys know what works ( for them and for you), and they are all very good at their art.
Last edited by Nader; 05-25-2011 at 12:12 AM.
OK, ogive. It ain't a guess.
Ogive is expressed in diameters. Not calibers, diameters. A 7 ogive on a 30 IS NOT the same curve as a 7 ogive on a 6mm.
Here's a way to describe the ogive. We'll draw a bullet ogive on the wall.
- take a soup can and nail it to the wall laying "flat." (or you can just draw a soup can if'n you're artistically inclined and don't want nailholes in your wall....just don't get mixed up and draw a soupcon, wouldn't be prudent)
- now measure the diameter of the soupcon (ooops, soup can) let's just say it's 2 inches.
- now reach up a couple feet above the can and hang a plumb bob on the wall so it comes down in line with the end of the can (oops, there's a nail-in-the-wall!) Now you've got a layed down soup can with a vertical string hanging down juuust in line with the end.
Now comes the tricky part.
- measure up the string 6 diameters from the bottom of the can, in this case that will be 12 inches (6 diameters times 2 diameters) above the bottom or 10" above the top of the can.
- now DRIVE ANOTHER NAIL! (get used to it)
- hook a string to the nail, grab a pencil or a scribe (or even a sawzall if you want a permanent record) and draw an arc from the bottom of the can extending out like the bottom half of a bullet. If you want BOTH sides so's it looks like a bullet then repeat the procedure from the bottom side. (Just don't use the sawzall for this mark unless you want a sheetrock "bullet" to carry in your pocket.......)
- you've just described a tangent ogive.
You'se can do these all over the walls if you want to describe different ogives.
NOW, secant ogive. Move the nail..... keep the length of the string the same but move the nail so that it still intersects at the same point, the corner of the can (not con, no)
- you've just described a secant ogive.
useta'could you could search "ogive definition" on the WWW and get some good pix.
no longer, all pix I found were flawed
BTW, the way the realio-trulio dudes do the deed is using a cool device called an Optical Comparator which projects a hunnerd times enlarged image on the wall (no nails) for most 'scruciatin' accuracy. Said image is projected onto a grid........Cool tools indeed optical comparators, definitely better than sliced beets.
The guy didn't ask for a tutorial on bullet making or on ogives, he simply asked if tools were available to measure an ogive.
"BTW, the way the realio-trulio dudes do the deed is using a cool device called an Optical Comparator which projects a hunnerd times enlarged image on the wall (no nails) for most 'scruciatin' accuracy. Said image is projected onto a grid........Cool tools indeed optical comparators, definitely better than sliced beets. "
Mind bending thread fer sur...
I know of no device to measure an ogive >>accurately<< other than the Optical Comparator the die makers use.....
the Optical Comparator is what I use. An it's a Lufkin. Not that it's important.
Originally Posted by Cheechako
Ohhh, sorry Cheech
Although a picture is undoubtedly worth a thousand words, evidently the reverse is not always true.
A couple of other things... According to Hornady, for their secant ogives, the string is twice as long. And according to Dan Lilja, locating the nail gets a bit complicated. Hornady's drawing is a bit sketchy. If you draw a bullet that has a truncated cone for the ogive (straight line from end of shank to edge of meplat), whatever radius that you use for a secant ogive can be used to draw arcs that have pivot points where the profile of the cone intersects those of the shank and the meplat. Where these arcs cross is the the pivot point for laying out the curve of the secant ogive. (pictures would still be a lot better)