Best tool to measure base to ogive

[emcon5]

The hacksaw and the magic marker tell you when a dummy or gauge round is seated to zero bullet jump. But if you are using hollow point match bullets with nearly 0.015" variation in overall bullet length, you can't use the COL of any other bullet but that one to get a consistent determination of the ogive-to-base number. You can, however, improvise pretty nicely. Instead of an exact bullet comparator, you can often just invert a resized case over the bullet and measure the total length of the dummy/gauge cartridge and resized and inverted the case. Repeat that measurement as you seat the bullet down, with the difference being your bullet jump.

Right, but you can set your seating die which seats on the ogive (which should not have any significant variation, at least on good bullets) rather than the point (which as you say can vary quite a bit) using the same bullet you can get an acceptable result.

Use the split case to get a OAL for that bullet to the rifling. by "that bullet" I mean that specific projectile, not that box, not that brand, not anything else, that individual one.

Do it several times and measure OAL each time, make sure you are getting consistent results.

Now take that bullet and your cut case and put them in your press, and adjust the seating stem until the seated bullet matches the OAL you measured, plus however much jump you want. The ogive-to-base length should be pretty consistent for that bullet (here I mean that box/brand/make/model of bullets).

Can I say to the third decimal point what the base to ogive measurement is? Of course not, but that is not something that has any value to me. As the barrel wears, what you want that value to be is going to change anyway as the throat moves back.

[hounddawg]

Fguffy- There are at least two companies that are selling datums

they sell references from mechanical drawings that are used to define the geometry of the object ? how much do they get for one? I want to see this for myself. I also bet you can't post a pic of your mythical datum collection

[F. Guffey]

they sell references from mechanical drawings that are used to define the geometry of the object ? how much do they get for one? I want to see this for myself. I also bet you can't post a pic of your mythical datum collection

That almost qualifies as 'talking it to death'.

Again, for years I have insisted the Sinclair/Hornady too was a comparator, reloaders insisted they could go from the Hornady tool to SAAMI specs; when doing so they insisted they were missing something. The datum used on the Sinclair/Hornady too has a radius, if it was a datum it would have a sharp edge. The sharp edge is what I identifies as being case unfriendly. And it goes on and on, I will say again, you would not recognize a datum if you saw one.

F. Guffey

[F. Guffey]

Right, but you can set your seating die which seats on the ogive (which should not have any significant variation, at least on good bullets) rather than the point (which as you say can vary quite a bit) using the same bullet you can get an acceptable result.

It does not have to be that way; a reloader without shop skills if left hit and miss methods or seating and checking and seating and checking etc. if they get it correct they have to start all over the next day. And then there are the squid lipped cases, just shred the neck with a hack say, I know, it makes sense to all reloaders, I did say there were a lot of reloaders that seem to be challenged, I believe reducing bullet hold is a bad habit; if spreading the neck has something to do with neck tensions, shred away.

F. Guffey

[hounddawg]

da·tum
ˈdādəm,ˈdadəm/Submit
noun
1.
a piece of information.
2.
a fixed starting point of a scale or operation.

https://www.google.com/search?q=datu...hrome&ie=UTF-8

a datum is not a physical object, why you insist they are is beyond me. Misinformation is the bane of forums

[F. Guffey]

a datum is not a physical object, why you insist they are is beyond me. Misinformation is the bane of forums

I know what it is and I know where it is; all I need to know is the diameter. When I started reloaders were referring to the datum as a line, to help them an arrow was placed near the line identifying it as a datum line; then there was the rational, the rational finished with saying, "and that is how they do it".

You should have been there when I said the datum was not a line, I said it was a circle/round hole; the circle/round hole for the 30/06 case is
.375"

And at this rate you will never get around to measuring the length of the chamber from the datum to the bolt face.

F. Guffey

[JeepHammer]

Not a physical object, it's a 'Starting' or 'Zero Point' to start from.
As in starting from ZERO and counting up.
It's very real and no measurement, any number, can't be accurate without a fixed ZERO point.
Even though it's 'Nothing' you can't measure accurately without it, so it's the MOST important 'NOTHING' mankind has ever seen.

Datum is also the center, or tipping point in ANY balance measurement.
When your scale is showing ZERO, that's the Datum Point for positive or negative readings for weight measurement.
Without an accurate ZERO, there is no accurate measurement of weight, just a relative comparison.

Which brings us back around to RELATIVE measurements, comparing one weight or length to another...
Without knowing the EXACT measurement of your chamber throat, you can NEVER get an ABSLOUTE measurement of ogive on any particular profile of bullet.

This means taking any particular bullet and finding EXACTLY where it contacts lands in the bore.
With a bullet on an extension, copper tube, seated long in a case, etc, there is no way to make a PRECISE adapter for a measuring tool.
I simply use copper tubing that crimps/swages down on the specific bullet I'm using, solder it in place, and use the tubing as an extension to turn the bullet in the actual chamber throat.

This gives me a scratch on the bullet at exactly the part of ogive the bullet where ogive contacts bore.
That scratch allows me to make a simple adapter for a caliper or micrometer with a PRECISE sized hole for the bullet I'm using, in the chamber it's being fired through.

Much like a Datum Line based case shoulder adapter, but since I don't champfer or round the mouth of the gauge hole, it's direct read, not a comparator or guess based on the 'Average' contact point on a bullet.

What I will never understand is...
How you can get this far along, this advanced in making a reload that fits the specific chamber, and NOT know how to make a squared off, direct read adapter from simple bar stock, and NOT own a precision set of drills or know how to lap/home a hole to exact size.

'General' or 'Average' tools are for 'General' or 'Average' reloaders.
When you get this far along, NOT owning a Harbor Freight caliper, knowing how to read a micrometer, owning basic PRECISION tool is a requirement since you are past the 'Go/NoGo' general use gauges & comparison tools, it's time to step up to precision tools...

Just like the old saying,
'Horsepower costs money, how fast do you want to go?'
Precision costs money ,how precise do you want to measure?

[JeepHammer]

As for 'Drawings', good luck with that!
The 'Drawing' DOES NOT take into account wear on rifling buttons, wear on chamber tools, throat erosion from bullets and gas jets slamming into it...
Let's not forget, the 'Certified' chamber drawing has about ZERO to do with what the chamber reamer maker did. Finding a chamber reamer that exactly matches SAAMI drawing is next to impossible since chamber reamer makes produce what sells, and for DECADES users have demanded off specification (users 'Twist' on what they call a 'Better' chamber).

I cut Chambers in three steps, throat, shoulder, body since I have a hell of a time even special ordering chamber reamer that are exactly SAAMI, and it's ALWAYS a crap fight on the phone with sales staff since they want to sell you 'There Improvements' instead of what you want...

And, again, we are back around to using the SPECIFIC bullet you intend to use, and getting a gauge line on that bullet from the actual throat you are trying to fit...
Anything else is 'Relative', 'Conjecture', 'About', 'More Or Less', anything but specific.

[cw308]

You guys should work for the manufactures , reloading doesn't sound like fun. I remember when I first started to reload , I was happy when it just went bang without blowing my face off. Then when you get into accuracy , it's a different ball game . Now I wish I paid more attention . If it wasn't for sports I'd still be in high school. I must say though your posts are informative , even if it's out of my league. Thanks Guys.

Chris

[JeepHammer]

Call it 'Human Error'.
The error is to believe the sales hype on any given packaged product.
Someone is TRYING THEIR BEST to sell you something...

When you are dealing with YOUR specific firearm, or YOUR specific brass coming out of your press,
They would have to show up and PRECISELY MEASURE your specific set up to produce anything that precisely fits YOUR firearm.
The problem is, they don't.

I remember a thread not to long ago about a guy having issues with cartridge over all length.
I said to simply make a round that fits into his magazine so he knows it mag/feed,
The get an 'L' bracket & hose clamp from the hardware store, put the 'L' along side his case Go/NoGo body gauge, drop that functioning round in the gauge, and the lower leg of the 'L' should touch the bullet point, tighten down the hose clamp...
Now his gauge show him over length rounds at a glance.
Long rounds wouldn't seat in the Go/NoGo gauge.

People blew up! Some said you NEVER modify a gauge in any way, some said to measure each round with a caliper/micrometer, one even implied the gauge would some how make the round unsafe to shoot...
I guess the idea was too simple to grasp.

Once you know the precise ogive diameter of YOUR throat, that diameter hole can be drilled in exactly the same kind of gauge 'L' lower leg.

This will give you a quick reference gauge to tell if ogive is going to hit the throat or not.
It's NOT an exact, absloute measurement, it's a 'Quick Gauge', just like the case body gauge is a quick gauge you started with.
It's now a Datum line on the shoulder to ogive quick gauge, since case quick gauges index (Zero, Datum) off the shoulder.
Simply tells if you got the ogive too far forward... Like all quick gauges, it's a Go/NoGo indication.

*IF* you can make a consistent case, (human error)
*IF* that case fits the chamber, (human error)
*IF* you don't screw the case up during loading, (human error)
*IF* you can seat a bullet consistantly, (you guessed it, human error)

THEN you need a way to measure the ogive to case base.
Case gauge checks the case (for human error) and since the bullet sticks out the end of the case gauge, a simple bracket (L or U shaped) hose clamps on the gauge body,
Drilled with your chambers specific diameter ogive hole, gives you a Quick Gauge to check your work.

Like I said before, the ONLY way to know EXACTLY what the ogive diameter is in the first place is to use the specific bullet you intend to fire,
Put an extension on it so you can get it in and out of the front of the chamber,
I use cheap copper tubing with a bullet sacrifice soldered onto their bullet,
And put the bullet against the throat in the chamber, turn the tubing about 1/6 turn and extract.

This will show you EXACTLY where the rifling lands scratched the bullet.
This is the EXACT spot the rifling will hit that particular bullet, expressed in a circle around the bullet (diameter hole) you will need to make a direct read adapter or a quick gauge.

Go to ANY hobby machinist or machine shop, anyone with a lathe.
Have a piece of bar stock first pilot drilled for center, then drilled/reamed out until the hole is big enough to reach the line on your test bullet.
Then simply face the bar stock off square, and cut it off square.
This is your direct read adapter for precision measuring equipment.
The adapter goes in the measuring tool & gets measured. This is the number you subtract from total.
Then you put a completed round in the adapter and measure again, subtract adapter from total, exact ogive to base measurement.

The adapter will be fairly short, it only has to cover the distance from bullet ogive scratch to a little past the point of the bullet. Small enough to misplace...
If you want to attach to to a caliper, then add about 5/8" for the attachment slot and screw.
See case Datum length adapters for slot/screw attachment.

The same size hole drilled into an L or U bracket attached to a case gauge will give you a quick reference gauge, Go/NoGo, based on the shoulder of the case, this means you MUST make CONSISTANT Datum length cases...
If your bullet is seated too long, the case won't seat in the gauge.
If it's seated too short, there will be a gap between bullet and adapter you attached.

This isn't difficult or expensive, it's just necessary for precise measurements.
The cost will be about the same in total as for 'The Nut' which is 'One Size Fits Nothing' since there is no way to order one that fits YOUR chamber. It's a general comparison tool for general use...

[cw308]

Jeephammer
In a way I do that with my rifle . I first used the Go Gage in my rifle chamber with a stripped bolt ( Rem 700 ) using only the housing , closing the bolt the bolt dropped with no resistance . added .002 shim there was a very slight resistance . To me that is zero headspace , for a 308 my chambered 1.632 , from there I take that measurement to size my case an measuring with my RCBS Precision Mic . Wouldn't that get me close to exact . I use the same bolt an sized case to find my ogive setting .

Chris

[T. O'Heir]

None. Ogives have nothing to do with OAL. OAL is measured from the pointy bit to the flat bit.
"...a gage..." Is a word that is misspelt.
"...a datum..." Is a random spot on a curved surface.
"...digital head space gage..." No such thing. A headspace gauge is nothing more than a go/no-go gauge that tests tolerance.
"...RCBS Precision Mic..." "It’s an indispensable tool for safe, accurate loads that extend the life of rifle brass." Is marketing BS.

[F. Guffey]

"...a gage..." Is a word that is misspelt.

I have a Starrett Machinist handbook, it goes back to about 1908; from the beginning to the end as in from page one to the last pace Starrett uses gage. I also have a Starrett catalog form about 1915, same thing; Starrett list all gages as being 'gage'. I am not the only reloader on this forum that has a Machinist Handbook, again, same thing.

I was cleaning up a few micrometers, about 80, one of the small micrometers had a 1896 patent, it seems they made the same gage for close to 50 years without the patent date.

I am going to stay with Starrett, John L. Hinnant used a drawing of a go-gage, He used another version of the spelling, and that is OK.

F. Guffey

[TailGator]

It is my understanding that machinists regularly spell "gauge" as "gage" and that it is thus an accepted alternate spelling. I see it all the time in reloading forums.

[cw308]

I don't really care about the spelling of the word Gage . A question I asked JeepHammer am I wrong by checking sizes my way? I'm not a machinist , I'm not in the big league's. It's a great hobby for me , without going so deep . Is my system of sizing OK.

[JeepHammer]

cw308,
I mean no disrespect by this at all, but I wasn't aware you had a 'System' or even method of measuring the ogive contact point. You mentioned 'The Nut' which is a random, generic comparator adapter.

I thought you were asking how to specifically measure YOUR chamber so you could find YOUR Chamber to bullet contact diameter on a specific bullet shape.

Defining the issue, you MUST know precisely what the diameter of your chamber throat is.
A bullet in an extension works to find that diameter.
Epoxy a bullet on a wooden dowel rod, epoxy or solder one to a piece of tubing, set/crimp one REALLY LONG in a case, doesn't matter as long as the bullet reaches the throat.

Plug that bullet into 'The Nut' and see where your actual bullet profile lands...
You might get lucky and 'The Nut' is correct, or 'Close Enough'.

Without the actual throat diameter with the bullet you are wondering about, since it's a taper on a taper, you won't know.
Once you have that diameter off the test bullet, you can make a REALLY CLOSE guess with all other bullets since the taper on .308 bullets doesn't change a crap load unless you start shooting round nose!

'The Nut' will be fairly close, but it's not YOUR chamber...

[reinert]

I use the Hornady Lock-N-Load system, and for how I shoot, and for how I reload, it works fine. The system I have is the bullet comparator with the basic insert set (.224, .243, .257, 277, 284 and .308). My interest lies in good hunting ammo, and I'm not terribly concerned about making one hole groups with any of my rifles; if I hit the same hole twice (or more) whilst shooting for group over my daypack, GREAT! I just want good ammo that's going to work through the action with good hunting accuracy when that moment of truth comes along in the field. I am completely confident with my hunting reloads, and have been successful enough in the field to say so.

The other tool that goes with the comparator set is the Hornady straight O.A.L. gauge. This uses a modified case for each/any caliber you want to make measurement on, and it too, works very well for me. I used to do the bullet marker bit, but always found it wanting for a better way. I have it now. You just put what bullet you want to use in the modified case, insert/chamber the tool, move/slide the bullet forward 'till it touches the rifling, lock the tool, back it out and measure with the comparator set (you MAY need to lightly nudge the bullet out of the rifling with a rod after extracting the tool). Measure your free bore to wherever you want it, and your done; set your seater die accordingly. Whenever you change to a different weight bullet, you just run the system to measure the new specs on the new bullet. Easy, and safely accurate (IMO).

I pretty much use Hornady bullets in all three of my '06s, my 6mm Rem. and my .223. Generally, if I'm looking to buy bullets, and if I see on the shelf that there's a couple of boxes that are of the same lot, I'll buy them both, and use the Lock-N-Load tools without any thought as to ogive consistency. I figure the ogive on the 200 pills I just purchased should be fairly consistent. Anyway, I like the Hornady system very well to measure the proper C.O.A.L. on my reloads (as I use them). These days, my .223 bolt gun gets shot the most.

Though I haven't used it yet on any "testing," I did buy a modified case for my two M336s. It'll be interesting to see what kind of free bore they have if I decide to try a "custom" 30-30 load. They might have to be fed singly in those old Marlins.

[cw308]

I tried an have the Hornady Lock - N - Load thought it wasn't so precise .I like using a stripped bolt seating the bullet long , going through lowering the seat until the bolt closes without any resistance. Where doing the same thing , only I'm using my bolt . It does take time but I find it dead on . I use a case with .001 headspace . Found the same way as ogive setting .

[cw308]

JeepHammer
I think your mixing me up with someone else . I never used that hex nut , I know of it but never gave it a try . The comparator I do have but found the PM Mic easier and I double check with the comparator . Even measuring powder with the RCBS ChargeMaster 1500 I dump that charge into the pan on the GemPro 250 scale . I take my time I'm only loading 30 rounds of 308 to shoot every Sunday weather permitting . My rifle is blueprinted , so I only blame myself if my groups open up . 2500 rounds down the second barrel ,

[JeepHammer]

OK with me, sorry if I confused you with someone else.
I don't shoot bench rifles much anymore, I'm down to one, and I have the load worked out for it.
I do usually get an idea of the throat opening diameter when I'm building a rifle, most people ignore it anyway so it's no deal.
Since I make the case/round gauge out of the excess barrel the gauge is usually within 0.001" or less of what the actual chamber is, but that's before you hammer the throat with bullets.

Unless you are trying to get a specific distance off the lands, it's usually just seating the bullet long and letting the bolt push the bullet back to zero. Once chambered, you simply eject and measure and set your bullets from that point minus what ever freebore you want. (Bullet jump, or what ever people are calling it today).

[cw308]

JeepHammer
I tried soft seating an remove the case an measure , the problem the rifling would grab on the the bullet an pull it out slightly every time . You can cut steel , I have enough problems with wood . Easier to buy those mindless tools . Thanks for all you help full information . Respectfully.

Chris

[F. Guffey]

JeepHammer
I tried soft seating an remove the case an measure , the problem the rifling would grab on the the bullet an pull it out slightly every time .

Too much time is wasted on trying to prove 'it can be done'; I have never been a fan of squid neck cases, I am the fan of 'all the bullet hold I can get'. With bullet hold I am not required to start over the next day and the day after that etc. etc..

F. Guffey

[JeepHammer]

Simply remove extractor and open bolt, the test round will be left in the chamber with no extractor.
Then you GENTLY push/tap it loose from the rifling with wooden dowel rod or brass tipped cleaning rod.
(Never stick anything steel down a barrel from the muzzle)
Don't hit it harder than needed to dislodge the bullet and the case/bullet will come right out without moving the bullet in the case.

Don't know if it will work for everyone, but the last time I did one, I wedged a bullet into the plastic end of a chamber protector and got the ring on the bullet.
Not all chamber cleaning adapters will have the right size plastic nipple on the end, this was just a fluke, but it might work for someone...

As for the adapter being metal, who says it has to be metal?
A good hard wood that's really dry would work, but would swell with humidity.
Hard synthetic is rigid enough for measuring force, and works as easily as wood.
Derlin comes to mind immedately.

[F. Guffey]

Simply remove extractor and open bolt, the test round will be left in the chamber with no extractor.
Then you GENTLY push/tap it loose from the rifling with wooden dowel rod or brass tipped cleaning rod.
(Never stick anything steel down a barrel from the muzzle)
Don't hit it harder than needed to dislodge the bullet and the case/bullet will come right out without moving the bullet in the case.

A waste of time; a reloader with shop skills and a fundamental understanding of transfers would have the project under control and finished.

And bullet hold: it helps if the reloader is a fan of bullet hold, I am the fan of bullet hold; I want all the bullet hold I can get.

F. Guffey

[jmorris]

A waste of time

Kind of what I was thinking after 49 posts.

“Best tool for making relative measurements from an irregular sufface to a flat surface”, would be a better title.