What is the proper term for measuring from the bullet ogive?

[mikld]

Would anyone knowingly use a 17 caliber tool to measure a 30 caliber
round?

Reason for my post;

Actually base to ogive would be a comparative measurement dependent on the diameter of the measuring tool, i.e. The measuring tool diam. would have to be included in the specs.

Example: C.B.T.O. at .177 diam.

[Duncan74]

What?

[Duncan74]

Some of yalls comments are like outter space talk. Some of the comments have nothing to do with my question that I asked.

This thread is completely off subject now.

[Duncan74]

The question I had has been answered. Thanks for all your help.

[cw308]

I agree. Till the next time, Be Safe.

[Metal god]

I use a comparator to take that measurement and refer to it in my notes as my comp measurement . I do how ever like the CBTO or even better BTO

Many , MANY guys use the term case/cartridge head space which distinguishes it from head space which is a chamber measurement .

[nhyrum]

Originally Posted by AllenJ

I saw in a publication stated as "Cartidge base to ogive" or "C.B.T.O." I've always used that to descibe it.

+1 on that

Sent from my SM-G920V using Tapatalk

[Dufus]

The only abbreviation I have ever seen is CBTO.

[schmellba99]

I just simply call it "Ogive Measurement". Nothing fancy for me, I know what it means and how I came about such a measurement.

Some of you folks get way, way, way, way too wrapped up in simple semantics....

[pnac]

This answer your question,mikld, the .177 I gave was purely a hypothetical for illustration. My tool for measuring .30 cal is .296 diam. I believe.

My reasoning is that I want the measuring tool diam close to bore diam of the rifle so, say, .010 of meas. to ogive translates to .010 adjustment of my seating die. Or close,anyway.

[Duncan74]

I like this abbreviation much better than what I was using in my notes. This is what I have decided to start using in my notes. Thanks.

[F. Guffey]

This answer your question,mikld, the .177 I gave was purely a hypothetical for illustration. My tool for measuring .30 cal is .296 diam. I believe.

If your .30 caliber is .296 it is too small in diameter, my 30 caliber barrels have two diameters one is supposed to be .300" and the other .308". Meaning the bullet will imprint on the rifling between the two diameters and then there is the bullet friendly bevel.

So when using a transfer I imprint the bullet, I know that makes them ugly but once I determine the beginning of the rifling I do not have to start over the next day.

F. Guffey

[flashhole]

You misinterpreted his post. He's referring to his tool dimension, not his barrel dimension.

[F. Guffey]

You misinterpreted his post. He's referring to his tool dimension, not his barrel dimension.

This answer your question,mikld, the .177 I gave was purely a hypothetical for illustration. My tool for measuring .30 cal is .296 diam. I believe.

There is no way to misinterprete if he finishes with "I believe" and I start with:

If your .30 caliber is .296 it is too small in diameter

He believes means he does not know and if I start with if means if the diameter is .296" he could drop his tool thorough the barrel.

F. Guffey

[tomhh]

I like the name OgAL as the name for this measurement.

[RC20]

From the bullet ogive TO WHERE????

Ogive is the curve of the bullet's forward portion. Hornady defines both a tangent and a secant ogive.

Your question is unclear to me, exactly what you are measuring, from where to where??

Oh come on. Its perfectly clear, sheese.

[RC20]

Lets call it COL. (Cartridge Ogive Length)

I just have it listed as OG or write Ogive. as I am not 44 AMP its clear to me I would not measure the bullet ogive on one end and to the moon on the other.

As the Ogive is only really relevant ot seating a bullet to as consistent a depth as you can, its a self fulfilling prophecy at it were.

[Tinbucket]

...to rifling begins..... Leade.

[44 AMP]

Lets call it COL. (Cartridge Ogive Length)

ok, what point on the ogive??

From the base of the case to ..what point?

Ogive is the curve of the forward portion of the bullet. What point on that curve are you using for the reference point? and, why?

[Metal god]

From the base of the case to ..what point?

Well that depends on if your asking for a standardized area or just a place you should use . I'd think there are a couple ways to go about this . Let's say if we were looking to have a SAAMI spec for this it would be the area .020 smaller in diameter then the caliber/bullet . So a 308 bullet would be measured on the ogive area measuring .288 . I just made up the .020 maybe .010 or .015 smaller would be better , That's for those with a higher pay grade . That way it does not matter the caliber . You just use the proper insert diameter .

If it's for a reloader just measuring/comparing . It does not really mater as long as you use the same insert on everything in that caliber . If you're not looking at or have a standardized area to measure to or from then just pick a diameter insert and always use that diameter and insert . Keeping in mine that the closer the diameter of the insert is to the diameter of a given caliber/bullet the better and more consistent it should be .

Meaning if you're measuring a 308 you would not want to use a insert diameter of .100 or something . Generally the closer you get to the tip of the bullet the more inconsistent it is likely to be .

There is a third option I see and that's making a cast of your chamber and throat or slugging the barrel to get the exact diameter of your bore . Then use an insert diameter a few thousandths smaller then your lands or maybe even the same size . Keeping in mind this method would be firearm specific .

I see all three working . Some better then others but all should get you where you're going .

[F. Guffey]

Ogive is the curve of the forward portion of the bullet. What point on that curve are you using for the reference point? and, why?

Why? I do not like starting over every day as though I was waking up in a new world and nothing I learned yesterday is going to make my life easier today. The only way a person can wake up in a new world everyday is to forget what he learned yesterday or does not have a clue.

Reloaders are too busy trying to reinventing the wheel; the wheel has been invented and America has been discovered/found. And then it comes to one of those 'and then' moments.

What point on that curve are you using for the reference point? and, why?

Why? 'again'; the question should be 'HOW?'. If I want to know where the bullet contacts the rifling I look at SAAMI specifications. The two diameters of the 30 caliber barrel are .300" and .308". And then! it get complicated; the reloader must know the distance from the .300"/.308" diameter of the barrel to the bolt face. Deterring the distance from the contact point between the rifling and bullet has never driven me to the curb.

I drill the primer pocket/flash hole out of the case to a diameter that will accommodate a cleaning rod. I size a case then seat a bullet with all the bullet hold I can get (everyone else uses reduce neck tension), they reduce neck tension by shredding the neck until it looks like a squid. 'AND THEN! I remove the bolt and chamber my test case, after chambering my test case I use a cleaning rod to push the bullet out of the case until it contacts the rifling I make sure the rifling imprints on the bullet. 'WHY DO I DO THAT?' This is not about being kind to your bullet, it is about imprinting the beginning of the rifling on your bullet so tomorrow you are not required to start over. After I imprint the rifling on the bullet I measure the diameter. The complicated part? The diameter can only be from .300" to .308" and then there is a slight bevel/chamfer. The bullet hits the chamfer at the smallest diameter.

Again, after I push the bullet into the rifling I take my test case our of the chamber and then set it up in my seating die. For those that are keeping up I do not measure the distance from my imprinted bullet to the case head, I use my test case as a transfer meaning I transfer the dimensions of the chamber to the seating die 'BECAUSE! I want to seat my bullet 'off the lands'. When I set my seating die up on my test case I am 'ZEROing' off the lands. If I want .025 off the lands I lower the seating stem .025". And if tomorrow I do not want to start over like I learned nothing today I can save my test case with all the bullet hold I can get. Others are required to start over because they reduce the bullet hold of the neck by turning it is to something that looks like a quid.

And then someone should wonder about the imprinted bullet on my test case; the imprint on the bullet is for tomorrow, it is not necessary to start over everyday.

F. Guffey

[higgite]

Originally Posted by Metal god

If it's for a reloader just measuring/comparing . It does not really mater as long as you use the same insert on everything in that caliber . If you're not looking at or have a standardized area to measure to or from then just pick a diameter insert and always use that diameter and insert . Keeping in mine that the closer the diameter of the insert is to the diameter of a given caliber/bullet the better and more consistent it should be .

It doesn't get much simpler than that.

[44 AMP]

What point on that curve are you using for the reference point? and, why?

Why? 'again'; the question should be 'HOW?'.

No, the question is "why", I already know how. "Why", in context, meaning why pick that particular point on the ogive, to use as your reference point?

The OP was a very "open ended" question, I think, all it asked was if there was a term for "measuring from the ogive.."

"from" implies a "to". From the ogive to some unspecified point. Many are assuming the point is the rifling. Some the base of the case, or the boltface. The OP DID NOT SAY.

From where on the ogive??
What point on the ogive is it being measured from? The most forward point where the bullet is still full caliber? From the point where it is .010 smaller than full caliber? .020", .030"???

Again, the OP did not say. Without more information, it is neither simple, nor perfectly clear, to me.

I also cannot see what the point of such a measurement might be. OK, so you want to keep the bullet a given distance off the rifling..fine. Each bullet type, style, brand, weight, is slightly different. The measurement can only apply to one specific bullet, and since that is the case, why measure from an unspecified (and possibly difficult to repeat) point on a curve, when you could just use the overall total length and get the same results (bullet .xx" off the rifling)?? (once you know what that distance is, for the specific bullet)

What keeps popping up in my mind is the example of a .30 cal Hornady 220gr RN, and their 150gr Spire point. Measuring "from the ogive" (to any given point) will give you different results (IF you are consist about where on the ogive your data point is...) because of the vastly different ogives of these two bullets.

[F. Guffey]

Keeping in mine that the closer the diameter of the insert is to the diameter of a given caliber/bullet the better and more consistent it should be .

It doesn't get much simpler than that.

If the insert is the diameter of the bullet the insert will be .308" for the 30/06, the way I have it figured the bullet will slip through the Insert.

One more time, the two diameters for the 30/06/308 caliber bullet is .300" and .308" meaning the 'measure from' has got be between those two diameters. The diameter will not change from day to day but after continues use the length will chamber because of throat erosion.

F. Guffey

[F. Guffey]

What keeps popping up in my mind is the example of a .30 cal Hornady 220gr RN, and their 150gr Spire point. Measuring "from the ogive" (to any given point) will give you different results (IF you are consist about where on the ogive your data point is...) because of the vastly different ogives of these two bullets.

I am referring to a diameter, when I know the diameter of the rifling all I have to do to find the contact point on the bullet . It is not magic; I find the contact point on the bullet by measuring the diameter of the bullet. I can measure the diameter of the bullet three different ways. A tool maker with minimum shop skills can make a tool that measure the distance from the contact point to the top of the bullet in in short time and make the measurements as fast as the reloader can pick up and put the bullet down.

The datum finds the contact point on any bullet if the reloader knows the diameter of the datum. Again, there is a lot about the datum the reloader does not understand. And then again, again; I do not make bullet friendly datums, I want my datums to cut the bullet so I can see and measure.

F. Guffey