Measuring Ogive to Base

[Poconolg]

I am now using the Sinclair Hex Nut with a caliper to measure ogive to base for my 22-250 cartridges. It seems to be working well. I am looking for a tool that will give even better results. I was told the Redding Instant Indicater will give even better results. Has anyone used this tool for this purpose or is there a better tool out there?

[Unclenick]

Better in what way? The instant indicator, I believe, will allow you to measure the difference from the shoulder to the bullet ogive, which is what determines bullet jump to the lands. But call Redding to confirm this. I made my own tool for before the Instant indicator came out. The Redding tool uses their bushing die inserts to serve as measuring diameters, so you get to choose whether to measure a diameter that tells you where the bullet will touch the lands or to measure one where your seating die pushes on the bullet.

[cw308]

RCBS Precision Mic , started with Hornady comparator the Mic is used for headspace an ogive measurements . Tried them all , wish I knew of the Mic , would have saved money in the long run , very easy & accurate tool to use , check it out .

[RC20]

( edited response to CW308)

What advantage over the comparator?

Bullet ogive would look to vary more than the limits of the tool.

[Poconolg]

I want to make sure my bullets are seated to within 1 1 thousands of an inch. I want to do anything to improve my groups. Right now I am shooting 5 shot groups at 100 yds under 1/2 inch. I shoot 8 5 shot groups a week. Of those 8 groups 2 or 3 are 3/8 of an inch and at least once a week or every 2 weeks I shoot 1/4 inch groups. I want more consistent ammo to shoot better. Also what do you think of using JB every couple of weeks to clean the barrel. Right now I use Butches Bore Shine and a bronze brush every 25 rounds.

[RC20]

JB bore paste? I think that is like that stuff they used to show on TV that lets your engine run dry. It actually works. But then it also destroyers the bearings insie of 10 hours or some such. Tried in WWII by the USAAC and it was not worth destroying an engine over.

Ok, frank view. Just because you can measure it does not mean it has relevancy on accuracy.

Efforts are best spent in other areas, more shooting, neck tension, minim shoulder bump back.


I will defer to others, but I don't believe even .005 get you anything.

You can measure powder down to the 1/10 of a grain, how you hold your file affect the velocity variations more than 2 or 3/10 of power difference.

Ergo, once you are at 1/10 a scale that measures .0005 does you no good. A tenth above or a tenth below give you 2/10 accuracy and that's is far more than good enough.

[RC20]

I have not used BBS.

What I do use is Carbon Killer 2000 for the most part. If I am looking at copper (usually in older guns) I use Bore Tech Eliminator .

With the CK2k I use a nylon brush, with an eyedropper . Put it on when the gun is still warm at the range run it through, saturate it on the far end, run it through 4 of 5 times.

Then the last pull through I saturate it, pull it out and run a dry patch through.

There are some similar but that stands up as equal to the best.

I have a boroscope and can confirmed how clean it gets a gun, including some grungy mil surplus guns that now look brand new.

A bit of copper is merely coating over rough areas, that's ok.

I have looked at some seriously rough barrel that shoot fine.

The issue is not shooting, its cleaning. Rough barrels are harder to clean. The CK2k is a big change and help.

[Jim Watson]

want to do anything to improve my groups. Right now I am shooting 5 shot groups at 100 yds under 1/2 inch. I shoot 8 5 shot groups a week. Of those 8 groups 2 or 3 are 3/8 of an inch and at least once a week or every 2 weeks I shoot 1/4 inch groups.

That is exceptional accuracy for anything but a dedicated benchrest rifle.
Do your larger groups have obvious "out" shots or are they uniform, just bigger?
What rest and technique do you use?

[Poconolg]

Many times I shoot groups and they are 3/8 or under except for the flier. If I didn't count the flier I would always shoot in the 3's or 4's. If I didn't count the flier I would only be cheating myself.

[mehavey]

I want to make sure my bullets are seated to within 1 1 thousands of an inch.

Tell us again what your precision requirements are.
"1[space]1"[sic] thousandths doesn't compute no matter how I interpret it.

[RC20]

.001, it makes sense to me as far as the precision.

It does not make sense as far as having any affect on accuracy.

Bench rest shooters do it in the ones with common seating methods.

[Unclenick]

1 1 thousands = one one-thousandth, I expect. It's a common colloquial usage that is redundant, as merely saying "one thousandth" or "two thousandths" instead of "two one-thousandths" covers the meaning in modern usage.

I agree, though, that as far as bullet jump goes, that level of precision is lost in the noise of other factors. The variation, within the same box, of bullet ogive length between where the ogive will contact the throat and where the seating die contacts the ogive will see to that. About 0.002" is as close as I've been able to achieve using sorted components without a second seating step.

Additionally, none of the tools except, from what I see for the instant indicator, tells you the critical piece of information for rimless bottleneck cases, which is the distance between the shoulder the case stops against and the and part of the ogive that contacts the throat. The Precision Mic and Hornady comparator inserts will do it in two steps. For the PM, use the case thimble with a loaded round to measure the shoulder datum distance from the base, then swap in the bullet ogive thimble and measure that, recording the difference between the two measurements. Then go to the next round and repeat. Sort the loaded ammo into lots by matching those differences. For the Hornady tool, measure all your loaded rounds with the case comparator insert in the caliper adapter, sorting by the result, swap in the bullet comparator insert and measure them all again, resorting by matching the differences in the two measurements. If you want to get really anal, with either instrument, sort all rounds by the initial shoulder datum results and then sub-sort within each group by the difference in that measurement to the ogive location measurement result.

As to which tool you use, that is mostly personal preference to my mind. The Hornady is quicker, but it takes more skill to make a caliper repeat as consistently as the PM does. See which one you are comfortable with. Or get the instant indicator.

[Poconolg]

This is for unclenick. At 100 yds does 1 or 2 one thousands of an inch really matter for accuracy?

[Unclenick]

If you are talking about adjustments to bullet jump, I don't believe so. Too many top match shooters, based on their loading methods, have more round-to-round differences in their loads than that. Also, too many folks have the experience that altering seating depth in relatively big increments does more for load tuning than benchresters used to accept. Berger has a good article on this. The late Dan Hacket had the experience of a 0.030" change in seating depth from 0.020" off the lands to 0.050" off the lands making an improvement from 0.5" groups to 0.2" groups with a 220 Swift (little 50 grain pills). If he'd spent his time fiddling with 0.019", and 0.021", trying to identify improvements, I think he'd have shot the barrel out before he got where he actually needed to be.

I have looked at lots of targets from guys playing with numbers in the single digits of thousandths of seating depth change like that, trying to spot an improvement and have come away with the impression, from what I know of the nature of random error and the tendency of the human brain to fail to identify it correctly, they were "seeing improvements" that were actually just random. If they were shooting five or six groups of each load to prove them and using radial standard deviation or even mean radius instead of group diameter as a measure, I think they would mostly have been discouraged to find no clear improvement. They would find the groups at each such small difference in seating depth traded places all the time as to which was smallest.

If you want to improve groups, I think it's much more important to eliminate finished cartridge runout, learn to seat primers properly, find a forgiving powder charge that doesn't mind if you are off a half a grain (because even if you hold your charges to a tenth, you will inevitably get into weather or other conditions that affect the load equivalent to a half a grain of charge error anyway). Finally, play with changing bullet position in 0.03" steps like Berger does. Make it 0.020", if you are more comfortable with that, but don't waste barrel life on 0.005" changes. Bullet variation is going to give you that anyway, over time, so you want the seating depth as forgiving as you want your powder charge in order that bullet tolerances don't move you off your best spot.

[RC20]

Basic question:

I know Berger did it with their VLD (from memory)

Has anyone done a test with other bullets and are there differences in the various profiles?

I seldom do less than .010, but that's from what I have seen of variation that it needs to be at least that to make any difference and I suspect no less than .020 is more likely.

[Unclenick]

As I mentioned, Dan Hackett reported moving a 50 grain Nosler BT from 0.020" to 0.050" off the lands in a .220 Swift to get five-shot groups down from an average of 0.50" to about 0.20". So we know it can happen with regular bullets.

[hooligan1]

I move bullets in an out in every load Ive tried in my rifles, and what I have found is that some bullets like a jump of .100 or more even, and some only .010.
And yes Unclenick you can wear a rifle out testing every measurement and still not be happy..
Im happy if a rifle will consistantly shoot 3/4 moa or less.

[cw308]

RC20
To your question , what advantage over the comparator. I find the Mic holds the case level & also is used for headspace adjustments. For me it works better an that's what the OP was asking . If you like the comparator thats your call.

[RC20]

That is all I was asking.

I like to find out why it works for someone else.

Some of it I adopt and some either its not an issue for me or I am vested and not enough better to change that.

[Gary Wells]

Just curious but what make of rifle & what scope.

[cw308]

RC20
Why it works for someone else . Because the comparator an the Mic both will measure from base to ogive just as accurate as the other . One may like one system better , either one will do the job. The OP was looking for other options . I just gave him mine.

[Gary Wells]

cw3o8:
It would depend entirely upon what type of comparator you are talking about. Although not designed for home use, I have used optical comparators in aerospace facilities that will read in thousands and be just about as accurate as a coordinate measurement machine (CMM) which will read in tenths of a thou.

[F. Guffey]

I have used optical comparators in aerospace facilities that will read in thousands and be just about as accurate as a coordinate measurement machine (CMM) which will read in tenths of a thou.

I had the opportunity to purchases an optical comparator, it came complete with instructions; it did not take me long to make up my mind. I choose a Pratt and Whitney electronic gage. I found it very annoying because it has a small range that started at .00005" and maxed out at 0005. I removed the electronics and then turned the Pratt and Whitney gage into a dial indicator stand; that is what L. Willis calls a digital head space gage and reloaders do not know the difference.

F. Guffey

[JeepHammer]

This might be a difference between military & civilian terminology & common useage,
Or from the older folks to current useage...

We always called 'Bullet Jump'... Free Bore (Freebore) since there wasn't contact between bullet & chamber/barrel/rifling.

The second term that seems muddy is the 'Throat', 'Forcing Cone', etc.
From my very old gunsmith books and chamber drawings, traditionally lead bullet chambers, say 'Forcing Cone', while later jacketed bullet chambers say 'Throat'.

The third issue I see is 'Accuracy' used where it should say 'Consistent'.
Building ammo you are trying for a CONSISTENT product, so when you make changes you have a 'Zero' or starting point to move FROM.
A definitive, provable change from one cartridge build to another.

'Accuracy' is the end result, the 'TERMINAL' results.
'Accuracy' involves EVERYTHING, from the loose nut behind the trigger, to sights & sight lines, to weather conditions, to everything involved with internal & external ballistics.

This is one of my pet peeves, but I confuse the two all the time myself when I'm talking/writing because they are confused in common useage so often.
Someone says 'Accuracy' when they should have said 'Consistent' and I'm right there on the band wagon with them! I SHOULD know better, but my brain simply complains later instead of correcting me on the spot...
-----

Anyway, more to the point,
Measuring the Ogive to case head IS a much more accurate way to make CONSISTANT rounds for ONE SPECIFIC CHAMBER. No doubt about it! No argument...

The problems start when you don't have an exact, measured & absolute distance from Throat/Lands of the rifling to the case head.
This measurement also changes with wear of the throat, so you have to keep up with your throat erosion/wear of the lands of the rifling.

Freebore/Bullet Jump (whatever) is all over the place, some fast magnums came from the factory with 0.300", while some came with virtually zero, both shot equally well.
I find the intermediate velocity/pressure rifles shoot pretty well with minimal jump.

As for finding the actual (absolute) length of the cartridge, that's sometimes a pain.
The issue I have with most 'Gauges' is rounded, or radius on hole on the gauge.
A radius let's the bullet sink deeper into the gauge, which screwed up the absolute reading, instead giving a 'Relative' measurement.
A square edged hole can be a challenge (like with Datum line gauge adapters), but it's an accurate reading.

Since you are working with a taper in the chamber, matching that taper precisely (which will change with wear) is almost impossible, so generally it's accepted machinist practice to use a square edge on the gauge/stop which produces the best absolute measurement.

The issue I have with the premade 'Nut' gauges is the holes have radius, and the nut sides aren't precision ground, so each set of flats are a different size, you have to measure the 'Nut' (gauge) and subtract the distance between flats.
MUCH easier when all flats are the same distance, like 2", you simply subtract 2" from relative reading g for the absloute reading...

I suggest you hold the gauge 'Nut' in your hand BEFORE you measure, since body heat will expand it and change your initial measurement of the gauge...
When you are working 3 or 4 places behind the decimal point, this matters...

The BIGGEST screw up doing this is getting the CASE Datum line to bolt space correct BEFORE you try and install a bullet!
If the case isn't fitting the chamber LENGTH, distance from Datum line on case shoulder to bolt face, it doesn't matter what the ogive to case head distance is.
The only exception is zero 'Jump', the bullet against the rifling taper.

The case is simply going to slop around in the chamber and screw up you 'Jump' distance anyway...

This takes an ACCURATE measurement of the headspace of your chamber ('Headspace' defined as the CHAMBER, bolt face to Datum line on the chamber shoulder.
You simply beat the brass into a shape that fits the headspace in the chamber.
Datum line gauge adaptors are notoriously inaccurate when you attempt to find the ABSLOUTE headspace length, again because they have a radius at the measuring contact point... And when made of aluminum in particular, they expand with body heat during useage.

From a tool & die maker, I drill/hone the opening (hole) to exactly the Datum line diameter, and I DO NOT radius the opening so the gauge stops the case at exactly flush with the face of the gauge.
I do the same thing with ogive gauge adapters.
With razor sharp, exactly 90* opening faces, it makes getting the measurement a little more difficult since brass/bullet tend to hang up on the edge once in a while, but it gives EXACT readings.

If you don't beat the brass, the brass WILL beat you.
When I'm doing bench rifle rounds, it's all about EXACT PRECISION/CONSISTENCY,
Not 'Within' any +/- range, and since I've invested that much time already, might as well get it dead on to the 4th decimal place...

[Joe-ker]

Unclenick: In post 14 you mention--learn to seat primers right--- to improve accuracy. Can you expand on this? Maybe I've been doing something wrong. Thanks.