Bullet comparators

[Eagle Trapper]

Do many of you hand loaders use one? Do you find it makes a good bit of difference? If you answered yes to either question, where the heck do you find one?

[densa44]

What are they and what do they do?

[gitrdun]

I assume those meant to measure seating depth. If so, I got mine from Flys Etc. Those that I couldn't find, I made.

[20shadow05]

I use them and they are great and very useful. P-D-ent carries them or you can always order from Brownells.

[elkhunter11]

I don't use one, I use a bullet that just slides in the case with finger pressure, to determine the approximate distance to the lands. I seat the bullet way too long, chamber it several times, and take measurements until I get several consistent readings.

[gitrdun]

Originally Posted by elkhunter11

I don't use one.

Meaning that you measure COAL to the bullet tip ???

I think that we need clarification from the OP as to what he means. I assume the devices that clamp on to caliper jaws to measure off the ogive rather than the tip.

[Eagle Trapper]

I wasn't aware there was any other type then the ones that measure the O.A.L off the ogive rather then the tip of the bullet, but these are the ones I'm speaking of. Seems like every time I turn around there's something new or I haven't heard of in the reloading game. Thanks for the tip on where to find one!

[elkhunter11]

Originally Posted by gitrdun

Meaning that you measure COAL to the bullet tip ???

Yes, and then I use that same bullet to do the initial setup on my seating die. Using the same bullet eliminates tip to tip variations. Then I use the micrometer adjustment on my seating die to vary the seating depth. Once I have determined the seating depth that works best, I reference the reading on the seating die, and I don't bother measuring the COAL again.

[gitrdun]

Originally Posted by Eagle Trapper

I wasn't aware there was any other type then the ones that measure the O.A.L off the ogive rather then the tip of the bullet, but these are the ones I'm speaking of. Seems like every time I turn around there's something new or I haven't heard of in the reloading game. Thanks for the tip on where to find one!

OK, we seem to speak of the same device. They used to be made by Stoney Point, now bought out by Hornady. Likely not to be found at the big box stores, they sell socks and cameo ginch.

[260 Rem]

Originally Posted by densa44

What are they and what do they do?

They are used to take a measurement on the bullet ogive as opposed to the OAL measured to the bullet tip. The ogive measurement is generally accepted as being more accurate. I use the Hornady style, which has a base that attaches to the caliper jaw..and fitted with interchangeable caliber specfic bushings. Most often used with the Hornady OAL Guage.

[Eagle Trapper]

Thanks fellas, since your all here, do you measure your max C.O.A.L of your specific rifle with the method elk hunter mentioned or do you use an actual devise?

[gitrdun]

Originally Posted by Eagle Trapper

Thanks fellas, since your all here, do you measure your max C.O.A.L of your specific rifle with the method elk hunter mentioned or do you use an actual devise?

No way. I use the comparator always. Should my seating die be set up for say a 7mm 100 gr. bullet, and I leave it alone, it will be pointless in setting seating depth for a 140 gr. I keep comparator length in my load data, I ignore COAL since bullet tips are inconsistent.

[elkhunter11]

Originally Posted by gitrdun

No way. I use the comparator always. Should my seating die be set up for say a 7mm 100 gr. bullet, and I leave it alone, it will be pointless in setting seating depth for a 140 gr. I keep comparator length in my load data, I ignore COAL since bullet tips are inconsistent.

I use the same method for every bullet type that I try in a given rifle, and I always use the same bullet that I used to establish the distance to the lands to set up my seating die, which rules out bullet tip differences as a variable. And it's not even about knowing the exact distance to the lands, but rather knowing the setting on my seating die that will produce the best accuracy. Once my seating die is set up for a given bullet, I never measure the COAL again, I just dial my seating die to the correct setting.

[Tall Texan]

Originally Posted by elkhunter11

I use the same method for every bullet type that I try in a given rifle, and I always use the same bullet that I used to establish the distance to the lands to set up my seating die, which rules out bullet tip differences as a variable. And it's not even about knowing the exact distance to the lands, but rather knowing the setting on my seating die that will produce the best accuracy. Once my seating die is set up for a given bullet, I never measure the COAL again, I just dial my seating die to the correct setting.

Doesn't make sense to me. Your seating die will seat from the ogive or some other diameter and all bullets don't have the same shape? Seating depth is only meaningful if you set from the ogice and must be done for each different bullet. Maximum accuracy is about knowing the exact and preferred distance from the ogive to where it contacts lands.

[elkhunter11]

Seating depth is only meaningful if you set from the ogice and must be done for each different bullet.

Which is why I do the same measurement procedure with every bullet type that I intend to test, before I start loading for a new rifle.

Maximum accuracy is about knowing the exact and preferred distance from the ogive to where it contacts lands.

Actually you don't have to know the exact distance to the lands to achieve maximum accuracy. You pick a starting point and use the micrometer graduations on the seating die to vary the seating depth, until you determine the most accurate setting on the die, and then record that setting. It doesn't matter what the actual distance to the lands is, as long as you know how to set the seating die to achieve that seating depth. Whether you use a comparator or the setting on the seating die, you will ultimately be depending on the seating die producing consistent seating depths.

[gitrdun]

Seems as though elk uses micrometer seating dies. I Don't, but I do set up a dial indicator on top of my seater adjustment. I prefer to measure ogive comparator and repeat it with my set up. To each his own as long as the results work.

[gitrdun]

Originally Posted by elkhunter11

Which is why I do the same measurement procedure with every bullet type that I intend to test, before I start loading for a new rifle.



Actually you don't have to know the exact distance to the lands to achieve maximum accuracy. You pick a starting point and use the micrometer graduations on the seating die to vary the seating depth, until you determine the most accurate setting on the die, and then record that setting. It doesn't matter what the actual distance to the lands is, as long as you know how to set the seating die to achieve that seating depth. Whether you use a comparator or the setting on the seating die, you will ultimately be depending on the seating die producing consistent seating depths.

Sorry elk, but I don't like that approach. You are relying on a seating die setting and ignore actual jump to lands. That to me is something that I like to know. Your way seems to me a bit like going in blind.

Oh, and remember elk that no everyone is as fortunate to own micrometer seating dies...lol.

Which is one of the reasons that I prefer Lee seater over RCBS. I can set up my dial plunger on a Lee, can't do that on a screw head.

[elkhunter11]

Originally Posted by gitrdun

Seems as though elk uses micrometer seating dies. I Don't, but I do set up a dial indicator on top of my seater adjustment. I prefer to measure ogive comparator and repeat it with my set up. To each his own as long as the results work.

Yes I do use Redding match seating dies. Once I have a starting point, I use the micrometer settings to vary the seating depth, until I find the optimum seating depth. Then I record the setting on the seating die, and it's easy to reproduce that setting any time that I need to.The actual distance to the lands doesn't matter, as long as I can make my seating dies produce that seating depth.

Sorry elk, but I don't like that approach. You are relying on a seating die setting and ignore actual jump to lands. That to me is something that I like to know. Your way seems to me a bit like going in blind.

Unless you adjust your seating dies for every single round that you load, you are ultimately relying on your seating die to produce consistent results.

[gitrdun]

[QUOTE=elkhunter11;2945966]Yes I do use Redding match seating dies. Once I have a starting point, I use the micrometer settings to vary the seating depth, until I find the optimum seating depth. Then I record the setting on the seating die, and it's easy to reproduce that setting any time that I need to.The actual distance to the lands doesn't matter, as long as I can make my seating dies produce that seating depth.



Unless you adjust your seating dies for every single round that you load, you are ultimately relying on your seating die to produce consistent results.[/QUOTE]

I don't. I have a dial indicator sitting on top of the seater die knob to show the outcome. I measure random cartridges in my loading box when done with the comparator tool and they all come out identical.

[qwert]

Originally Posted by gitrdun

I use the comparator always.snip
I keep comparator length in my load data, I ignore COAL since bullet tips are inconsistent.

I consider comparators essential tools, and are important enough that I have one on a caliper at most times.

I have been doing load development on a new barrel, by seating a little long with low neck tension, then at the range, carefully extracting the cartridge after chambering and measuring and recording the CBTO (cartridge base to ogive) before firing. It is interesting to note the growth of the start of the lands as the throat breaks in. It gives me a large sample size and great confidence that I know the exact CBTO of that rifle.

The Hornady and Sinclair bodies use the same size bullet and case bushings.
The Hornady bushings have a square edge measuring surface.
The Sinclair bushings have a beveled measuring surface.
Some bullets prefer the beveled surface and some (VLD) bullets prefer the square edge, YMMV, I try both then record and use the one that fits most consistently.
I usually use the proper Sinclair case shoulder angle specific beveled bushing for measuring case shoulder length, but on occasion the Hornady square edge SAAMI standard datum diameter works best.
Dual bodies (mounted opposed on each caliper jaw) can be used to select bullets with uniform riding length.
The Sinclair XL body is long enough to measure case shoulder length over a seated bullet.
Both brands are sold by Brownells.

If you re-size a case of the same caliber with the expander removed from the die, it can also be used as a comparator, but this really requires more than 2 hands or the use of an aid or clamp of some kind.

IMHO, the only reason to measure COAL is to verify magazine length and clearance.

Good Luck, YMMV.

[elkhunter11]

I don't. I have a dial indicator sitting on top of the seater die knob to show the outcome. I measure random cartridges in my loading box when done with the comparator tool and they all come out identical.

Then there is no reason not to trust your seater die. As to the micrometer mechanism on my seater dies, how often do you find it necessary to adjust the zero on your micrometers ? If they ever need adjustment, what is the most that they have been off of zero?

[gitrdun]

Originally Posted by elkhunter11

Then there is no reason not to trust your seater die. As to the micrometer mechanism on my seater dies, how often do you find it necessary to adjust the zero on your micrometers ? If they ever need adjustment, what is the most that they have been off of zero?

Because you use a Rockchucker elk, in which the seating die is seated firmly and you can get repeatable seating from your micrometer seating die. I don't, I use a Lee turret die. In which there is axial play in the turret. I do take out some of the play with shims. However that play which most think is a deterrent in fact isn't due to the slightest wobble that allows the die to float so to speak. I gave up one definition of seating accuracy for another. My gain is reduced run-out. My loss is seating depth accuracy which I deal with and check with my comparator tools.

[elkhunter11]

Originally Posted by gitrdun

Because you use a Rockchucker elk, in which the seating die is seated firmly and you can get repeatable seating from your micrometer seating die. I don't, I use a Lee turret die. In which there is axial play in the turret. I do take out some of the play with shims. However that play which most think is a deterrent in fact isn't due to the slightest wobble that allows the die to float so to speak. I gave up one definition of seating accuracy for another. My gain is reduced run-out. My loss is seating depth accuracy which I deal with and check with my comparator tools.

We do use different equipment, and we we each have a method that works with our equipment, which is all that really matters.

[Eagle Trapper]

I have been under the impression it is important to know where your bullet contacts the lands, so then you can back off .0020 off the lands " the apparent sweet spot to start". Which brings me to another question, i've seen guys say .0050 off the lands is huge jump, but if that's the case factory is massive jump, being .150 or more off the lands. Any insight on this, I'm aware factory has to be made to fit all clips chambers and barrels. N I also use the rock chucker, once I set it, it's good to go. Tricky part is where do I set it.

[qwert]

Originally Posted by gitrdun

Because you use a Rockchucker elk, in which the seating die is seated firmly and you can get repeatable seating from your micrometer seating die. I don't, I use a Lee turret die. In which there is axial play in the turret. I do take out some of the play with shims. However that play which most think is a deterrent in fact isn't due to the slightest wobble that allows the die to float so to speak. I gave up one definition of seating accuracy for another. My gain is reduced run-out. My loss is seating depth accuracy which I deal with and check with my comparator tools.

Are you using a Lee standard combination seating/crimp die?
or a Lee Dead Length Seating die with no crimp function?

Since the Dead Length Seater die is designed to have solid contact with the shell holder, I find that there is no loss of repeatable seating depth when used in an un-shimed Lee CC Turret press, people report the same experience when these dies are used in a Dillon 550-B, but the 550-B shell plate is not a rigid as a standard shell holder in a solid ram.

I use the Redding Competition shell holder set to get the same solid shell holder contact when partial resizing using a FL die, and have never felt the need to shim my Lee CC Turret or Dillon 550-B tool plate.

IMHO the Dead Length seaters are a very good (and cost effective) design, and I avoid using standard combination seater/crimp dies whenever possible. If required I prefer to crimp using a Lee Collet or Factory crimp die in a separate operation.

IMHE the Redding Competion micrometer seaters are the very best, but they do require changing the seater plug for VLD bullets. I use these dies in a solid frame CC SS press and not a CC Turret.

Good Luck, YMMV.

[qwert]

Originally Posted by Eagle Trapper

I have been under the impression it is important to know where your bullet contacts the lands, so then you can back off .0020 off the lands " the apparent sweet spot to start". Which brings me to another question, i've seen guys say .0050 off the lands is huge jump, but if that's the case factory is massive jump, being .150 or more off the lands. Any insight on this, I'm aware factory has to be made to fit all clips chambers and barrels. N I also use the rock chucker, once I set it, it's good to go. Tricky part is where do I set it.

I suspect that the major concern of the factory is that their ammo fit in a SAAMI standard magazine, most target shooters single feed cartridges that may be too long for a SAAMI standard COAL magazine. The exception would be CRF actions like some Mauser, Ruger and Win 70, that must feed from the magazine.

There are several schools of thought regarding seating depth.

CAUTION, Increasing CBTO and seating 'on the lands' can cause a pressure spike,
AS ALWAYS, START LOW AND WORK UP, watching carefully for all pressure signs.

Many report increased accuracy when seated on the lands, and there are several explanations for this. The better bullet to bore alignment (when seated in a properly fire-formed and concentric case) is obvious.
Some suggest one of the advantages of crimping is more consistent combustion and higher pressure at the instant of bullet release from the case neck. Since few of us crimp our bolt action loads, we are depending on neck tension alone, and this can vary widely unless it is carefully controlled with neck bushing dies and neck turning for consistent neck wall thickness. I suspect that seating 'on the lands' can achieve a similar effect as crimping.
If load development is done 'on the lands' and stopped at signs of over pressure, then we can be confident that pressures are not likely to increase when we try other amounts of 'jump to the lands', and loads may even need to be increased to achieve the same MV and barrel harmonics.

Many report that solid copper/guilded metal bullets work best with more of a jump than standard cup and core or VLD bullets, YMMV. The bullet manufacturers offer specific recommendations on what their research has shown and is usually a good place to start.

All bullet designs and individual rifles are unique and require experimenting to determine what the individual rifle likes best.

Good Luck, YMMV.

[Tall Texan]

Elkhunter - still seems to make more since to me to go from the ogive. If you know that distance often it will be the same for different bullets whereas overall length has no relationship to the ogive. But whatever, as long as it works.

[elkhunter11]

Originally Posted by Tall Texan

Elkhunter - still seems to make more since to me to go from the ogive. If you know that distance often it will be the same for different bullets whereas overall length has no relationship to the ogive. But whatever, as long as it works.

As I posted, the actual measurement doesn't matter, as long as you are able to set your seating die to produce the best accuracy.

[Hotwheels81]

There is a bit of voodoo in ogive construction that's for sure...

http://www.accurateshooter.com/balli...ogive-bullets/


A good seating die will seat off the ogive of the bullet meaning any bullet you seat with it will have the same seating depth to the lands... But the world is not perfect nor are dies... Nor are bullets... It is nice with a bit of testing when you can seat a 139gr interlock instead of a 162gr Amax with no die adjustment and still be bang on tho

[FallAirFever]

Originally Posted by Eagle Trapper

I have been under the impression it is important to know where your bullet contacts the lands, so then you can back off .0020 off the lands " the apparent sweet spot to start". Which brings me to another question, i've seen guys say .0050 off the lands is huge jump, but if that's the case factory is massive jump, being .150 or more off the lands. Any insight on this, I'm aware factory has to be made to fit all clips chambers and barrels. N I also use the rock chucker, once I set it, it's good to go. Tricky part is where do I set it.

Different bullets have different reccomended distances to start off the lands. It's been a while since I worked up a new load but for bullets like Sierra Game Kings or Nosler partitions I'll start 20-30 thou off the lands. I believe mono bullets like Barnes they reccomend 50 thou. Check your loading manual. Then start testing some rifle / bullet combos will want a jump some will prefer to be right up on the lands. I like to stay off the lands for the reasons Qwert mentioned and to make sure I have enough bullet into the neck of the case. I have the Hornady OAL gauge and I like it to get my starting point. I don't believe tools like this are essential. There are many other ways to figure out where a bullet contacts the lands. Google will help you there.

Good luck!