Do you seat your bullet to OAL or ogive length

[Mikecr]

No offense, but in this area, you've seriously departed from reloading reality.

Max OAL tools are only used for making max oal (land contact point) reference rounds,, with particular bullet/ogive types seated. Having done this, put the tool away,, it did it's job.
Put that reference round in a drawer for future checks of land movement, and all seating reference -with that bullet, in that chamber.

DESIRED seating depth is ONLY bullet ogive to lands.
You externally measure that 'reference round' created, just like you will the rest of your loaded ammo.
[This is where I always use 'the nut']

Variance in bullet lengths makes no difference at all, as ogives of same bullets don't vary much in RADIUS. For different bullets[ex; VLD to AMAX] you modify another case, and create & hold another reference.

 

[Fitch]

No offense, but in this area, you've seriously departed from reloading reality.

It probably won't be the last time either. But I learn something each time.

Max OAL tools are only used for making max oal (land contact point) reference rounds,, with particular bullet/ogive types seated. Having done this, put the tool away,, it did it's job.
Put that reference round in a drawer for future checks of land movement, and all seating reference -with that bullet, in that chamber.

We are on the same page so far.

DESIRED seating depth is ONLY bullet ogive to lands.

Yup.

You externally measure that 'reference round' created, just like you will the rest of your loaded ammo.
[This is where I always use 'the nut']

Yup. The shiny stainless Sinclair nut. I use it to measure the round I create based on measurements using the rod with two sliding collars.

I also, when I've chambered the rifle myself, made a replacement for "the nut" by throating a cutoff piece of barrel with the chambering reamer.

Variance in bullet lengths makes no difference at all, as ogives of same bullets don't vary much in RADIUS. For different bullets[ex; VLD to AMAX] you modify another case, and create & hold another reference.

Some boxes of bullets will exhibit a noticable variation in base to ogive distance, sometimes several thousandts. This is variation within a box of the same bullets. That happens only because of shape variations. It is why measuring to the ogive makes more sense than using OAL.

In a perfect world the seating stem would only contact the bullet in the exact same place as the chamber throat resulting in the exact same jump for every cartridge. Alas, seating stems don't do that so one makes an allowance for this by making sure the variation won't put the ogive in contact with the lands by accident. That was my whole point.

One way around this variation, if one cares to zero it out, is to measure all the bullets in a box, sort them into groups, and adjust the seating die when changing groups. I don't do that. As long as the jump doesn't go to zero, or under .010", my rifles seem to shoot just fine. I'm hunting, not shooting benchrest.

I didn't think this was such radical thinking, I still don't.

Oh well ...

Fitch

 

[woods]

There are definitely differences in ogive curves

Example, here are 2 ea 200 gr Accubond bullets that weigh within .5 gr of each other

but have a comparator measurement from bullet base to the point where the comparator hits the curve of ~.016"

The holes in the comparators are not caliber size as Fitch is saying, this 30 caliber comparator has a hole that is .297"

Now on a slow curve like on the bullet the linear variation that occurs in between where the comparator hits at .297" and where the lands hit can have an effect on seating depth measurements. Same with a seating stem except much worse since the best I can tell, the first point on the inside of this 30 caliber seating stem hits the bullet at a diameter of .260"

That was on a regular RCBS seating die. I could take apart one of my Redding Competition Seaters and measure but I hate to take one apart since they are all set for my rifles.

 

[Fitch]

There are definitely differences in ogive curves

<snip>

Now on a slow curve like on the bullet the linear variation that occurs in between where the comparator hits at .297" and where the lands hit can have an effect on seating depth measurements. Same with a seating stem except much worse since the best I can tell, the first point on the inside of this 30 caliber seating stem hits the bullet at a diameter of .260"

That was on a regular RCBS seating die. I could take apart one of my Redding Competition Seaters and measure but I hate to take one apart since they are all set for my rifles.

You illustrate my point perfectly.

Thanks for taking the trouble to put together that post.

Fitch

 

[Mike6158]

Some boxes of bullets will exhibit a noticable variation in base to ogive distance, sometimes several thousandts. This is variation within a box of the same bullets. That happens only because of shape variations. It is why measuring to the ogive makes more sense than using OAL.

In a perfect world the seating stem would only contact the bullet in the exact same place as the chamber throat resulting in the exact same jump for every cartridge. Alas, seating stems don't do that so one makes an allowance for this by making sure the variation won't put the ogive in contact with the lands by accident. That was my whole point.

One way around this variation, if one cares to zero it out, is to measure all the bullets in a box, sort them into groups, and adjust the seating die when changing groups. I don't do that. As long as the jump doesn't go to zero, or under .010", my rifles seem to shoot just fine. I'm hunting, not shooting benchrest.

I didn't think this was such radical thinking, I still don't.

Oh well ...

Fitch

Yup... you speak the truth. Even "high dollar" bullets have variations. I use a Mic gauge to set / check seating depth and I see this all of the time. I used to jack around with each and every one but, like you, I found that for hunting and non-competition shooting it didn't make a crap one way or the other. I can't stand using OAL for measuring and setting seating depth... since it's pretty much MEANINGLESS sorry... didn't mean to yell... actually I did...

On the topic of ogive- the ogive is the curved part of the bullet, not a spot on the bullet.

In ballistics or aerodynamics, an ogive is a pointed, curved surface mainly used to form the approximately streamlined nose of a bullet or other projectile.

I wonder if the diameter Woods is seeing has something to do with the height of the lands... since the caliber of the rifle would be measured between the grooves, not the lands. Since we are seating on the lands... not the grooves, that would make the most sense to me
​

 

[woods]

That .008" difference between groove diameter and lands will throw the spot at which the comparator takes the measurement and the lands hit the ogive a little closer.

 

[roaddog1m]

Okay,I have a question. I'm an avid shooter an just getting started in reloading. I have a Savage 10FLCP-K chambered in .308 with a 1 in 10 twist. I'm trying to determine OAL using a marker and coloring the bullet. I have a fired, unsized case trimmed to 2.005. When I chamber a round in the case (either a hornady A-max or nosler Accu-Bond) the OAL I get is in the 2.88-2.91 range. Way over the SAAMI max of 2.81. Now, I realize that i'm measuring to to the bullet tip, not the ogive. I realize this isn't the most accurate method, however fitting in the magazine is not an issue. My magazine has enough clearance for more than 2.95. It seems like if I took these measurements (I lan on seating about .010 off the lands) the round would barely be seated in the case. What am I doing wrong? Advice?gun)

I also agree that you have a lot of "freebore" in your barrel. Try the 175 SMK. You will end up with more of the bullet in the neck of the case. I have a Rem 700 PSS .308 and I have my best luck right up against the lands. That of course means I have to single load the bullets.
Good luck!

 

[Mikecr]

Your flaw is measuring ogives from the base of the bullet, and twisting this to somehow mean something. It doesn't mean ANYTHING about bullet distance to the lands. Even ACTUAL CONTACT distance to your lands means nothing.
Also meaning nothing:
Boat tail length
Bearing length
Nose length
The comparison tool datum

All that matters is that you seat contact point from the lands the same distance your barrel tells you is best -everytime. Doesn't matter what that is, or what you think it is. Just pick a tool & put it there.
This couldn't get easier to do. But you analyze it as though bullet seating was just invented..

There are probably no problems with your seater contact points. They should be at a point that has most consistent hold under pressure, without damaging noses. If it were higher on the nose, seated depth would vary all over the place with neck tension variance. Just squish any reading you want with them calipers to see it. Too low on the nose and bullets won't seat straight.

The only things that can cause ACTUAL variance in resultant seating distance from the lands is an extremely poor stem match for the bullet(ex, bottoming), too much+highly inconsistent neck tension, and huge ogive radius variance(+-1/2cal and that's more than you'll ever see today).
But these won't be a problem for most reloaders.

Seating to a desired point is not a problem for most reloaders.

 

[Fitch]

That .008" difference between groove diameter and lands will throw the spot at which the comparator takes the measurement and the lands hit the ogive a little closer.

I think the hole in the comparator is land diameter, not groove diameter - it almost has to be to work correctly. The one in "the nut" is supposedly cut with a throating reamer which should give it a lead angle sort of like a rifle throat - the benefit of that is that it is slightly less likely to mark the bullet.

Fitch

 

[trueblue]

I will have to side with Mikecr on this one.
The ogive measurement from the base of bullet to ogive is irelevent to me when it comes to loading ammo. The only ogive measurement that I am concerned with is the measurement from the base of the cartridge to the ogive of the bullet, so that my bullet is seated the SAME distance off the lands every time. Very simple, don't complicate it.
Now if you want to sort bullets based on base to ogive measurement, fine, but I don't waste my time with it.

 

[Mike6158]

I must be mis-reading or not reading something.


My take on the posts Fitch put up was this- because there are minor imperfections in the construction of the bullet (also the press and dies for that matter), seating a bullet to the exact depth required to be an exact distance from the lands every time, without backing off and re-adjusting the seating die every time, is going to result in slight... and sometimes not so slight, variations in the distance the bullet is from the lands.

I've seen this many, many times. Bergers are pretty consistent but I've seen a few thousandths difference in the base of the bullet to ogive distance from cartridge to cartridge with Sierra bullets. I use Forster Benchrest dies and while there may be better dies out there (like Lee? ba-doomp doomp, cha- ching... thank you.... thank you very much, I'll be here all night) the micrometer seater is a very precise die and once it's locked into a Co-Ax press there's not a lot of variation that comes from there. My conclusion for the reason for this was that there must be some kind of variation in the construction of the bullet that causes the seater head to contact the bullet in a different location. I usually, but not always, load 50 rounds (a block) at a time. Sometimes I'll use the mic gauge on every single round and every time there will be some variation in seating depth of a fairly large population of the bullets. Mind you, not every bullet is different. In fact, most are the same or close enough to call it the same. Most of the time I'll check one in ten just to save my sanity.

Another plug for the mic gauge- I can't say with certainty because I don't own the tools to check it, but I think that the bore of the bullet end of the mic gauge is land to land diameter for the caliber that the mic was built for. So, what the mic essentially measures is the distance from the base of the bullet to the ogive diameter where it "should" contact the lands. Assuming that they got their thread pitch and scale right when they built the gauge, once I seat a bullet to just touch the lands and measure it with the gauge, I have a baseline value to use for seating my bullet to whatever distance from the lands that I choose until erosion lengthens my baseline and I have to make an adjustment.

Using my Sendero II in 7 mag as an example-

(1) I use the method that I like to determine distance to the lands. In my case I like to load the bullet that I am going to use in a sized and trimmed, but empty, case and chamber it. I look for land marks and, assuming that I find some, I measure (rough) the length of the mark and seat the bullet deeper by 1/2 of the measured value. I color the nose of the bullet with black magic marker and chamber the bullet again. I repeat the above process until there is a very slight mark from the lands on the bullet (I use a lighted magnifier to check). Once I am comfortable that the dummy round is "touching the lands" I measure it with the mic. In the case of my Sendero the value is .050". That is my baseline for this rifle. Side note- Bergers don't seem to have a lot of variation from bullet weight to bullet weight. Berger to Sierra is a different story but one is a tangent ogive and the other is a secant ogive so that's to be expected. I haven't checked Sierra weight to weight variation

(2) In step 1 I ended up with a seater die setting that is equal to the bullet just touching the lands (in my mind if nowhere else ) If I decide to seat .020 of of the lands I've learned to dial the die down about .015 and then make small (.0005) adjustments until the first bullet mic's to .030.

(3) If I am testing and want to make sure every single round is exactly the same seating depth, I back the die off a full turn and seat until I get .030 on the mic. If I'm loading a block to hunt with or punch holes in paper with my nifty looking, loud assed rifle, I seat the next one, check it, grumble if it's not quite .030, smile if it is, put it back in the block and seat another one. One exception to this would be if the depth is off by more than .005 or if I'm loading closer to the lands it the depth approaches the "touching mark".

My favorite thing is when I have cleaned the powder measure/scale out, put my powder away and other charging tools away, and I have a block of 50 PRECISELY charged cases ready for bullets. About 1/2 way through... or even better... on the last bullet to load... as I move the case to the press my attention wanders or whatever happens and CLANK I hit the side of the press and dump some or all of the charge out of the case That's just neato... I will sometimes use "incantations" (@%#^$) to try to cause time to reverse itself and put the powder back into the case but that never works.

 

[woods]

My take on the posts Fitch put up was this- because there are minor imperfections in the construction of the bullet (also the press and dies for that matter), seating a bullet to the exact depth required to be an exact distance from the lands every time, without backing off and re-adjusting the seating die every time, is going to result in slight... and sometimes not so slight, variations in the distance the bullet is from the lands.

That's pretty much it.

And for those that keep saying that the distance from the base of the bullet to the ogive is irrelevant, I am just using that variance to show how the bullet ogive can give variance to seating depth and distance from the lands. I am just a hunter also and only shoot hunting bullets in hunting calibers but if I were a benchrester then I would certainly sort bullets by bearing surface because I do think that it makes a difference.

So in that context, while I would say that the distance from the case head to the point on the bullet where it contacts the lands is most important, I would also say that the consistancy of the shape of the bullet and the consistancy of the bearing surface does have some effect on your group size and will have some effect on the other.