OAL length discovery and how you all deal with it

[Tuckerp229]

When attempting to set my OAL by thosandths off the lands I am discovering 1-6 thousandths variance in actual OAL, (as measured by the ogive-not the tip).

Where my exploration has taken me:

I have spoken with Hornady, Sinclair, Nosler, Lee, LE Wilson and my local reloading store. It seems that all bullets vary in OAL and more importantly they vary in ogive diameter. Hornady has a +/- 1thousandths but keep in mind that this is on a "slope" given that the ogive is a slope so any variance is magnified as the beveled seater stems seek to find a place to push the bullet into place.

I have been told to "sort the bullets" which can really only be done by weight since I know of no way to measure the ogive itself given that it is a slope.

What some of the companies told me:

Sinclair flat out stated that those that speak of "setting their bullets by the thousandths consistently are speaking through their testosterone."

Lee told me that given the variance in bullets it is impossible to do with any consistency and further that setting the bullet near the lands was primarily to control bullet movement before a uniform pressure was built up within the case and that by crimping one supersedes the "near the lands" technique.


How do you deal with the variance in bullet length as measured by the Ogive, (using a Hornady Bullet Comparator)?

Update:
Apparently I didn't use the best search terms plus I just stumbled on another nearly identical current post from another person struggling with the same questions ....my apologies to the collective.

 

[bheadboy]

consider the angle of the bullet ojive and the angle of the throat of the chamber you have two different angles entersecting.

thus, the exact measure you make on the bullet can be off +/- .002 just in the "feel" of the gauge you are using and the boattail length variation of .001 +/- which has no effect at this point

find a mid point that shoots and forget it.

Bob

 

[Beau]

I'm not a benchrester, just HP. I don't worry about it for mid range ammo. I just make sure I get a few that are close and go on and load the rest. I use a competition seater that seats off the ogive. It's close enough.

For short range ammo, I only worry about OAL and then I only bother with getting it within .01". Anything after the hundredths place is not significant.

 

[watercam]

I abide by the simpler is better train of thought. If you seat the bullets .005" or more 'long' with .001" or so neck tension, the bullet will find its own seat into the lands by being pushed back into the case by contact with the lands. This is fairly common amongst competitive shooters. The down side is the possibility of needing to extract an unfired rounds because of a called cease fire and probably having a case full of powder dumped into our action/trigger.
For myself, Hybrids or conventional non-VLD bullets offer good accuracy with bullets off or well off the lands. If you peruse and research you will find Sierras, Bergers, Scenars, etc. that offer good to great BCs that shoot well jumped into the lands.
I can not recommend Brian Litz's book Applied Ballistics for Long Range Shooting enough as a resource for bullets and ballistics in general. Actually, ballistics in particular!

 

[BlackEagle]

I think 0.02" (2 hundredths) off the lands is a good place to start. And settling on 1 hundredth increments is reasonably achievable. I don't think 1 thousandth is. Trying to find an accuracy node among 1 thousandth increments is probably not useful.

 

[mikecr]

Tuckerp229 you have so far been given bad information all the way around.
They represent appalling generalizations of reality.

-For one, it is very possible to seat bullets to EXACTLY the same OgvOAL.
It's just that bullets used to do this must be qualified in ogive radius and seating forces must be rational.
-Also, it is very possible to measure ammo at EXACTLY the same OgvOAL.
Again with qualified ogive radius(your datum), and consistent use of adequate tools.
-To end up with same relative seating distance your headspace needs to be set exactly, and again this is entirely possible.
-OgvOAL(seating depths) can be VERY important to accuracy, and should not be blown off by anyone.

 

[Tuckerp229]

Thanks all for the help. I understand the part that simpler is better, or pick a length and go with it or even that truth be told, my gun will out shoot me as is and finally why bother unless you are a benchrester?. I am trying to establish "good and uniform reloading practices. " I just believed that it takes the same amount of time to reload with the best measurements as it does "any measurement" so I started measuring. I had no idea that this measuring would introduce yet more levels of variables.

Blackeagle, how can you set your bullets with any consistency starting at 2 thou' and then testing at 1thou' increments? The first cartridge comes out spot on because it is the one the reloader is setting up the seater stem on and thereafter the OAL can be spot on or off by up to 6 thou' because of mere bullet variables. This means at 2 thou' of the lands the bullets may be anywhere from pushed into the lands, (actually pushed by the lands deeper into the case), to jumping the 2 setting plus up to 6thou' from the bullet variance.

It seems to me that locating the foremost portion of the bearing surface in nearly the same spot from cartridge to cartridge is the goal since this measurement is the one that the bullet companies concern themselves with the most and it is therefore most uniform.

Perhaps the Lee tech was on to something when he stated that tight proximity to the lands was primarily for producing the most uniform pressures from cartridge to cartridge which would also be why some benchresters use the lands to push the bullet into place upon bolt closure. I had thought that close proximity to the lands was to minimize bullet "cocking" relative to the barrel axis during bullet jump enter the lands.

 

[Tuckerp229]

Tuckerp229 you have so far been given bad information all the way around.
They represent appalling generalizations of reality.

-For one, it is very possible to seat bullets to EXACTLY the same OgvOAL.
It's just that bullets used to do this must be qualified in ogive radius and seating forces must be rational.
-Also, it is very possible to measure ammo at EXACTLY the same OgvOAL.
Again with qualified ogive radius(your datum), and consistent use of adequate tools.
-To end up with same relative seating distance your headspace needs to be set exactly, and again this is entirely possible.
-OgvOAL(seating depths) can be VERY important to accuracy, and should not be blown off by anyone.

Now you have my attention. How do you achieve this? I am all ears. Really!

Also , what are your thoughts about the idea that the ogive slope is important only as its diameter affects how deeply the bullet is pushed into the case by the seater stem? outside of this is not the bullet's bearing surface the most important thing? (of course I am not talking extremes here, bullet weight, ogive diameter/ length bearing surface length, boatail length and bullet end squareness all must be close extreme variances in these could change BC etc...).

 

[BlackEagle]

Thanks all for the help. I understand the part that simpler is better, or pick a length and go with it or even that truth be told, my gun will out shoot me as is and finally why bother unless you are a benchrester?. I am trying to establish "good and uniform reloading practices. " I just believed that it takes the same amount of time to reload with the best measurements as it does "any measurement" so I started measuring. I had no idea that this measuring would introduce yet more levels of variables.

Blackeagle, how can you set your bullets with any consistency starting at 2 thou' and then testing at 1thou' increments? The first cartridge comes out spot on because it is the one the reloader is setting up the seater stem on and thereafter the OAL can be spot on or off by up to 6 thou' because of mere bullet variables. This means at 2 thou' of the lands the bullets may be anywhere from pushed into the lands, (actually pushed by the lands deeper into the case), to jumping the 2 setting plus up to 6thou' from the bullet variance.

It seems to me that locating the foremost portion of the bearing surface in nearly the same spot from cartridge to cartridge is the goal since this measurement is the one that the bullet companies concern themselves with the most and it is therefore most uniform.

Perhaps the Lee tech was on to something when he stated that tight proximity to the lands was primarily for producing the most uniform pressures from cartridge to cartridge which would also be why some benchresters use the lands to push the bullet into place upon bolt closure. I had thought that close proximity to the lands was to minimize bullet "cocking" relative to the barrel axis during bullet jump enter the lands.

I said 2 hundredths, not 2 thousandths. Even if precision in the thousandths were reasonably achievable in this dimension(dubious) it would not be useful since the change in wind, temperature, and other random variables from moment to moment would make these precise measurements meaningless.

 

[Tuckerp229]

When i bought my wilson trimmer from a multiple Australian benchrest champ for my 6PPC he said once ive trimmed the case mouth turn the case and holder around and trim up the base aswell. He said that i will get more consistant measurements this way as the bases are not perfect, and to also turn the case holder half a turn as you trim the mouth.

Now I have to laugh. I was just reading another post about "Wilson Trmmers" and discovered an entry that described yet another variable. ugh.

 

[Tuckerp229]

I said 2 hundredths, not 2 thousandths. Even if precision in the thousandths were reasonably achievable in this dimension(dubious) it would not be useful since the change in wind, temperature, and other random variables from moment to moment would make these precise measurements meaningless.
[/quote]

Point taken. I read it, it registered and then I became lost in my answering multiple answers to my post. I am leaning heavily toward your declaration. It is disquieting however to read about legions of benchresters that speak forth this setting the OAL to the thousandths and thus far I am unable to see how they achieve it.
Perhaps legions is too strong but I am trying it say that it is one of the prevailing reloading concepts.

 

[bheadboy]

Tucker,

given the variables of shooter consistancy, wind mirage, primer, powder, case, increase in fowling in bbl with shots, shooter vision acquity, i suspect the absolute .0001" measurements some have spoken of are more a personal thing than identifialbe in the real world as to "the answer" or anywhere near being absolutely necessary.

Too many variable to get anal on one.

Bob

 

[tenring]

I agree with mikecr. But even with some custom bullets, ogive diameter varies. I can seat my bullets to within .001" using my Mitutoyo caliper and attached Davidson base and nose piece from Sinclair. Initially I set bullets to about .005-.009" longer than my target OAL. I have a delrin loading block with each line marked 1 to 0 with a marker. Seating 10 bullets at a time, I place them on the line marked by thousandths over. When all ten are in place, I move my micrometer seater adjustment down as needed. With careful adjustments, I can seat them right on.

 

[mikecr]

Anyone who thinks 2 hundredths in seating(20thou) is as close to precision that matters, because wind will be a factor anyway,, has likely never done anything towards producing the best ammo he can.

Have you ever noticed it's usually as easy to do things right, as doing them wrong?
You should at least notice that nothing is free. Right?
Now you can write-off efforts beyond poor shooting, but that's YOUR problem right from any beginning, and not so common among the rest of us.

Tuckerp229 there are many threads in this forum that can steer you to improved seating.
The question comes up a lot & the answers come up a lot.

 

[gotcha]

How do you deal with the variance in bullet length as measured by the Ogive, (using a Hornady Bullet Comparator)?

[/quote] No apologies necessary! This is a subject many of us struggle w/ regularly. I sort bullets by length then use Tenrings method for seating. Have no problem maintaining .0015" variance & this is not testosterone speaking..... Granted, this method doesn't compensate for variations in ogive shape as it relates to seating stem contact. Nor does it compensate for variations in the contour of the base. I do feel that the aforementiond variations are too minor to take seriously. Given, you're working w/ a batch of bullets made on a good day at the factory I would add that I'm presently working w/ 123 SMK's. 1st box sorted into 2 distinct lengths with less than .001" variance and 4 "throw aways" (pretty darned good!).... 2nd box had varied BTO by up to .012" & sorted into 6 separate groups? Short of HIGH dollar electronic lab scales & equally high dollar computerized optical comparators. I think we're only just "knocking on the door" of consistent seating depth & weight sorting w/ off the shelf bullets. Just my 2 cents.

 

[necchi]

Tuckerp,
I've read this whole thing and I can recognize your struggle.
Your mixing two variables, bearing surface and OAL,.
Your right, bullets have different length, but your measuring device will actually measure from the same place on the ogive, (the datum, or more precisely, your datum point) just like your seating stem wil contact the bullet ogive at the same point while seating.
While your caliper tool and or seating stem may contact the bullet at different datums, it doesn't matter, your wanting to achieve only one goal, having the bullet seated to the same OAL as it relates to the ogive position of the bullet in the case,,,
AKA: Cartridge Over All Length

The only way to get both exactly the same is to premeasure all bullets in the lot and select only the same prior too seating.
As pointed out there are a whole mess of variables that mess with the rifle and shooter.

Bullet variables are just part of the game, here's a tip;
Take your calipers and gently close the jaws and adjust zero. Now open the caliper too read .006 on the indicator and lock it down,,
Hold the caliper jaws up to a light and look at the gap.
8) You've got alot of different thing to worry about than that little gap ;D 8)
Cheers,

 

[BlackEagle]

My opinion on what is reasonably achievable is not the same as some people. Custom bullets are not something I use and I did not mean to suggest that there is no room for anymore improvement, ever. Right now if you can afford the very best tools and components and have the time you may be able to improve on 1 hundredth precision, but I still doubt it will improve your end result in a meaningful way. If you want to shoot like the the guys winning the tournaments, listen to what they have to say and practice shooting.

 

[Killshot]

Right now if you can afford the very best tools and components and have the time you may be able to improve on 1 hundredth precision, but I still doubt it will improve your end result in a meaningful way.

One Hundreth of an Inch (ten thousandths) tolorances aren't any where near "precision" when it comes to ammo. To say the smaller allowable tolerance doesn't improve the result makes me think you may not have the experience to advise others, no offense intended.

Berger bullets sorted to .001" and a Seating Die with .001" micrometer top makes getting all rounds to an .001" measurement a straightforward task, there is no magic or voodoo involved. And yes, one can see the difference on target of seating-depth variances as small as a couple thousandths.

Granted, that isn't going to happen with unsorted bargain bullets, cheap non-bushing dies and a $25 Harbor Freight caliper.

 

[BlackEagle]

Right now if you can afford the very best tools and components and have the time you may be able to improve on 1 hundredth precision, but I still doubt it will improve your end result in a meaningful way.

One Hundreth of an Inch (.010") tolorances aren't any where near "precision" when it comes to ammo. To say the smaller allowable tolerance doesn't improve the result makes me think you may not have the experience to advise others, no offense intended.

Berger bullets sorted to .001" and a Seating Die with .001" micrometer top makes getting all rounds to an .001" measurement a straightforward task, there is no magic or voodoo involved.

Granted, that isn't going to happen with unsorted bargain bullets, cheap dies and a $25 Harbor Freight caliper.

In the dimension (distance from the lands) we are discussing "One Hundreth of an Inch (.010") tolorances" are fine, at least for me and many others. If you think you can make and measure better ammo then by all means do so. You may be suprised if you look at the manufacturing tolerances of the components a lot of us use which are neither custom bullets nor "unsorted bargain bullets" (match grade Berger, Sierra and Hornady to name a few.)

Killshot, how do you find a node among .001, .002, .003, .004, .005, etc off the lands? And what practical use is that (theoretical) node?

 

[Tuckerp229]

Anyone who thinks 2 hundredths in seating(20thou) is as close to precision that matters, because wind will be a factor anyway,, has likely never done anything towards producing the best ammo he can.

Have you ever noticed it's usually as easy to do things right, as doing them wrong?
You should at least notice that nothing is free. Right?
Now you can write-off efforts beyond poor shooting, but that's YOUR problem right from any beginning, and not so common among the rest of us.

Tuckerp229 there are many threads in this forum that can steer you to improved seating.
The question comes up a lot & the answers come up a lot.

My point exactly...if I am willing to do a "reset on my reloading practices," incorporating some improvements over my old methods, once changed, the new reloading practices should cost me no more to do the job than my old way. I will try the search button some more for the better searches that will yield these threads you mentioned.