• Frank's Lesson's Contest

    We want to see your skills! Post a video between now and November 1st showing what you've learned from Frank's lessons and 3 people will be selected to win a free shirt. Good luck everyone!

    Create a channel Learn more

  • Having trouble using the site?

    Contact support

**WHY are my seating depths so different???

JC Steel

JC Steel

Gunny Sergeant
Commercial Supporter
Full Member
Minuteman
Oct 12, 2008
3,388
268
41
Washington State
#1
Hey Guys, I am needing some help.

I am loading for my 6.5x47 Lapua and am noticing that when seating bullets I am getting a super big gap between different bullets as far as the overall length is concerned.

I am using a forster benchrest seater, new 6.5x47 Lapua brass, 130 JLK bullets.

I am not touching or messing with the seater at all. Keeping it nice and tight where it should be.

I am seeing numbers like this,

2.825-which is where I want it at.
2.822
2.828
2.832
2.821

I am thinking to myself, something must be wrong.

That is a HUGE difference.

Is it something I am doing wrong?
 
#2
Re: **WHY are my seating depths so different???

Bullet sticking in the seater plug perhaps. Especially if your neck tension is kinda high, &/or compressed load. I have the same problem with my 300Wm & a compressed load.
 
#3
Re: **WHY are my seating depths so different???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jcvibby</div><div class="ubbcode-body">Hey Guys, I am needing some help.

I am loading for my 6.5x47 Lapua and am noticing that when seating bullets I am getting a super big gap between different bullets as far as the overall length is concerned.

I am using a forster benchrest seater, new 6.5x47 Lapua brass, 130 JLK bullets.

I am not touching or messing with the seater at all. Keeping it nice and tight where it should be.

I am seeing numbers like this,

2.825-which is where I want it at.
2.822
2.828
2.832
2.821

I am thinking to myself, something must be wrong.

That is a HUGE difference.

Is it something I am doing wrong? </div></div>

Going on memory, but as per VictorTN, who was in the bullet making business, most of the imperfections in bullet manufacture occur in the top 1/3 of the projectile.

If you were to go out and buy the Sinclair/Hornady/Stoney Point bullet comparators, you'd find that most quality bullets that you load will actually be quite uniform at the ogive vs. measuring the COAL.

This is normal. You really only care about where the ogive measures from round to round.

Don't sweat the irrelevant stuff.

Chris
 
#6
Re: **WHY are my seating depths so different???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChrisGarrett</div><div class="ubbcode-body"> If you were to go out and buy the Sinclair/Hornady/Stoney Point bullet comparators, you'd find that most quality bullets that you load will actually be quite uniform at the ogive vs. measuring the COAL.

This is normal. You really only care about where the ogive measures from round to round.

</div></div>

A timely and relevant post, as I have been faced with this same issue. I bought the gear to find out the chamber length of my rifle and was prepared to load to a specific ogive length, but I was given some advice by a trusted mentor to not eff with my process, because I was getting accuracy going by COAL. I have always taken the extra time to ensure COAL is the same on all my rounds. Loading to a consistent ogive length instead of COAL would definitely speed up my mass production for an upcoming training course. So, riddle me this.... If my gun shoots acceptibly well going by a consistent COAL, obviously if I go back and measure their ogive lenths would vary. I would have to shoot varied ogive lengths to find my sweet spot and recheck all of my loaded rounds?
 
#8
Re: **WHY are my seating depths so different???

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">So, riddle me this.... If my gun shoots acceptibly well going by a consistent COAL, obviously if I go back and measure their ogive lenths would vary. I would have to shoot varied ogive lengths to find my sweet spot and recheck all of my loaded rounds?
</div></div>

No, not obvious. Bullet meplat is where the variance lies and you can see this by measuring a series of bullet length compared to ogive to base.
Dependent on your seating die and bullet shape whether it seats by ogive or presses on the meplat; most seat by ogive.
I would be willing to say that if you measured your ogive to base you would find a great more consistency than a meplat to base measurement for your accuracy load.
 
#9
Re: **WHY are my seating depths so different???

How do you load to a set coal ?
Seat the bullet long , measure and then add necessary additional length and seat again for every bullet ?

The coal varies , because the bullets do.
But by seating to an Ogive length , this is a constant launch from ogive to lands every time.

Consistency sounds like the key to me, and a consitent COAL is taking into account in-consistant bullets
 
#10
Re: **WHY are my seating depths so different???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kyle MacDonell</div><div class="ubbcode-body"> How do you load to a set coal ? Seat the bullet long , measure and then add necessary additional length and seat again for every bullet ? </div></div>

Yes, that's why I thought seating to a consistent ogive would greatly increase my production time. My current process, though seemingly successful to this point, is sloooow.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kyle MacDonell</div><div class="ubbcode-body"> The coal varies , because the bullets do. But by seating to an Ogive length , this is a constant launch from ogive to lands every time. Consistency sounds like the key to me, and a consitent COAL is taking into account in-consistant bullets </div></div>

I've opted to not change my process in the past because of success with the COAL measured loads out to 1k. Maybe a consistent ogive length would improve an already good load?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: dammitall</div><div class="ubbcode-body"> I would be willing to say that if you measured your ogive to base you would find a great more consistency than a meplat to base measurement for your accuracy load. </div></div>

I agree... but my ponderence lies in this: If I already have 100 rounds loaded to a specific COAL. I now measure them for an ogive length, admitting that meplat to base measurements vary, I'm going to get different measurements. Do I average the ogive lengths from the COAL rounds? This is where the brainf@ck happened a few months back and my mentor put the fire out by saying, "don't try to fix something that ain't broke".
 
#11
Re: **WHY are my seating depths so different???

Are you actually adjusting the seating stem for each round you load? From reading your post, this is what it sounds like you do.

If you are doing that you are making a mess for yourself and creating huge inconsistencies in your ammunition.

Bullets vary in length. No way around that unless you use a meplat trimmer. (more wasted time in my opinion)

Set your seating die and leave it alone
 
#12
Re: **WHY are my seating depths so different???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Mike Casselton</div><div class="ubbcode-body">If you are doing that you are making a mess for yourself and creating huge inconsistencies in your ammunition.
</div></div>

Which created the question of why I'm getting accuracy out of "huge inconsistencies in your ammunition". I guess I can take 10 loaded to COAL and 10 loaded to ogive length and see if there's a big improvement.
 
#13
Re: **WHY are my seating depths so different???

Would love to hear some one chime in that is using a bullet pointing die without meplat trimming and their results along the OP's line of question.

If the answer is as I suspect, I better get ready for another purchase.
 
#14
Re: **WHY are my seating depths so different???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: GardDog</div><div class="ubbcode-body">Which created the question of why I'm getting accuracy out of "huge inconsistencies in your ammunition". I guess I can take 10 loaded to COAL and 10 loaded to ogive length and see if there's a big improvement. </div></div>


The bullet tips are going to vary up to .010 or so, maybe more. With your particular bullet in your particular gun it may shoot that bullet perfectly well seated anywhere from .010 to .050 off the lands. What you are doing is wasting your time by trying to hold the length to the tip constant when that isn't what matters - those tips do not contact anything inside your gun. The bullet manufacturer isnt making an effort to hold that constant. The distance from the ogive to your lands is what matters and decent bullets seated in decent dies will do a good job of keeping this very consistent with minimal effort on your part. Another aspect you are messing with is pressure as you scoot the bullet in and out, especially if you move it very far back or far forward into the lands. Assuming you dont create a pressure issue you wont see the difference unless you shoot very long range or over a chrono. If you then want to agonize over something else there are tools for uniforming the tips.
 
#15
Re: **WHY are my seating depths so different???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChrisGarrett</div><div class="ubbcode-body">
Going on memory, but as per VictorTN, who was in the bullet making business, most of the imperfections in bullet manufacture occur in the top 1/3 of the projectile.

If you were to go out and buy the Sinclair/Hornady/Stoney Point bullet comparators, you'd find that most quality bullets that you load will actually be quite uniform at the ogive vs. measuring the COAL.

This is normal. <span style="font-weight: bold">You really only care about where the ogive measures from round to round.</span>

Don't sweat the irrelevant stuff.

Chris</div></div>

This ^ get a comparator as suggested and then measure the COL. Lately my bergers have been 1-7 thousandths off with the caliper. Put the comparator on and i'm consistently getting 3.321COL.
 
#16
Re: **WHY are my seating depths so different???

Comparators are where it's at! I have used them for sometime now, can't imagine measuring COAL without them.
My first thought was a compressed load, but OP made no mention of this after the first reply mentioning it.
 
#17
Re: **WHY are my seating depths so different???

Ok so here's the deal....

Busted out with the Hornady gouge measuring tool on my caliper. I have measurements plus or minus .0015. Pretty consistent.

So I guess here is my next question. Why in the world would a match grade bullet I am buying be so darn inconsistent?  That's ridiculous! Some bullets are over .007 different from eachother. Wouldnt a different size bullet have a different BC and such? Of course it would.

Frustrating for me. Bullets are exspensive! And I'm a youth pastor so there really hard for me to afford. And to find out the different sizes ruffles my feathers.

I guess on the bright side I'll quite complaining because the inconsistent bullets keep going in the same ragged hole. Just my humble opinion!!!!


Thanks for looking and listening.

Have a blessed day

Jake
 
#18
Re: **WHY are my seating depths so different???

I was told the inconsistency is just a reality of the way the dies used to make the bullets work. Its not corner cutting on the part of the manufacturer.
 
#20
Re: **WHY are my seating depths so different???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: QuiggyB</div><div class="ubbcode-body">I was told the inconsistency is just a reality of the way the dies used to make the bullets work. Its not corner cutting on the part of the manufacturer.</div></div>

Measure the actual bullets and the meplats do vary a couple of thousands. Thats not to say they're "cutting corners" but bullets do vary. Thats not to say that some dies aren't better in controlling runout than the other also though.
 
#21
Re: **WHY are my seating depths so different???

This is why you measure to the Ogive instead of the Meplat for seating depth...

You can trim the Meplat (tip) if you so desire... but, in my opinion that's taking it a little too far...

Bottom line is, load them up and shoot... don't sweat the small stuff!
 
#22
Re: **WHY are my seating depths so different???

Rule of thumb is that trimming the meplat reduces BC by 2% IIRC i don't do it either. But there are plenty that do.
 
#23
Re: **WHY are my seating depths so different???

Jake, I spent a couple of days sorting 1000 bullets by ogive length w/ a comparator. Variances were .001-.003. (I attribute SOME of this to my lack of measuring skills. The boxes were yellow, btw & different lots...). After loading & seating,(using a micrometer seating die) I found COAL would vary by .001 -.007! (I attribute THIS variance to my seating technique). I could vary the COAL by how hard/how much force I put on the arm of the press. (It's a 1980 era RCBS Rockchucker. Perhaps some slop in the components? Don't know). I then sorted the loaded rounds into groups of similar COAL and either lowered the seating stem or "popped" the handle harder to get the desired COAL. Not scientific, I know but gotta work w/ what I got till I get something better. It means measuring EACH round a couple times, but since I'm only loading 50-60 rounds for a match, it's not too bad. All this effort will help me produce sub moa rounds and Lord knows I need all the edges I can get, but I question the effort for hunting and/or informal shooting.

Good luck. Let us know if you find out how to "fix this". Take care.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jcvibby</div><div class="ubbcode-body">Ok so here's the deal....

Busted out with the Hornady gouge measuring tool on my caliper. I have measurements plus or minus .0015. Pretty consistent.

So I guess here is my next question. Why in the world would a match grade bullet I am buying be so darn inconsistent?  That's ridiculous! Some bullets are over .007 different from eachother. Wouldnt a different size bullet have a different BC and such? Of course it would.

Frustrating for me. Bullets are exspensive! And I'm a youth pastor so there really hard for me to afford. And to find out the different sizes ruffles my feathers.

I guess on the bright side I'll quite complaining because the inconsistent bullets keep going in the same ragged hole. Just my humble opinion!!!!


Thanks for looking and listening.

Have a blessed day

Jake</div></div>
 
#24
Re: **WHY are my seating depths so different???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: GardDog</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChrisGarrett</div><div class="ubbcode-body"> If you were to go out and buy the Sinclair/Hornady/Stoney Point bullet comparators, you'd find that most quality bullets that you load will actually be quite uniform at the ogive vs. measuring the COAL.

This is normal. You really only care about where the ogive measures from round to round.

</div></div>

A timely and relevant post, as I have been faced with this same issue. I bought the gear to find out the chamber length of my rifle and was prepared to load to a specific ogive length, but I was given some advice by a trusted mentor to not eff with my process, because I was getting accuracy going by COAL. I have always taken the extra time to ensure COAL is the same on all my rounds. Loading to a consistent ogive length instead of COAL would definitely speed up my mass production for an upcoming training course. So, riddle me this.... If my gun shoots acceptibly well going by a consistent COAL, obviously if I go back and measure their ogive lenths would vary. I would have to shoot varied ogive lengths to find my sweet spot and recheck all of my loaded rounds? </div></div>

Appearantly your gun already has a little "wiggle room" in where it likes the bullets. Load up some of your regular pills, and then measure the ogives to get a range. Pick an ogive length in the middle and load away. Then you can tinker with the ogive length to fine tune your seating depth. Much more consistent than COAL.
 
#25
Re: **WHY are my seating depths so different???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: QuiggyB</div><div class="ubbcode-body">I was told the inconsistency is just a reality of the way the dies used to make the bullets work. Its not corner cutting on the part of the manufacturer. </div></div>

They're mass produced, man-made objects. You think a 500mg Tylenol weighs exactly 500mg throughout the bottle, lol? It's not a dose of Lithium.

This is why the guys who are really anal, buy 4x500ct boxes of bullets and then sort them down to a single box of 500, that they can then compete with.

This threads getting long, so I'm just throwing some crap out there in no particular order, for whoever wants to read/comment about it.

As far as bullet meplat trimmers and/or bullet pointing dies are concerned, I would think that if I was going to shoot SMKs (which are known to have meplats looking like the Swiss Alps,) in competitions, I'd trim them.

However, if I were going to trim my meplats, I'd probably just bend over and pony up for a Whidden bullet pointer to possibly gain back some of that fractional BC that I'd be losing by opening up those tips via trimming them uniformly.

For casual shooting like I do, I'm now spending a few hundred bucks and I'm spending some already scarce time doing that. Guys shooting in comps at 1k most of the time...sure they can probably benefit a lot from those two steps if they're not already shooting the poly-tips, or something like the Scenars that really have quite small and quite uniform openings.

For the guy who's COALs are uniform (and conversely the ogives are not) and who is still shooting well, that's fine. I don't think that we're talking about bullets spinning wildly out of control here, if our ogives are +/- .005" off of a baseline reference point, however, you'd want to put the ammo on a chrono (with a largish 40+ sample size) and see what's what.

You might notice a larger ES and at 1k, that can matter--100-300 yds, probably not so much so.

For plinking/practice/zombie ammmo, my standard has been +/- .005" for COAL. For the precision stuff, I find my lands with a particular lot of bullets using the Hornady modified case gage. I then record an average and try and match that up with the Hornady bullet comparators at the seating station.

Since things vary, I'm not going to be the guy who states that his ammo is exactly .01350" off the lands. I'll get things close and practice my stroke at the range.

Chris
 
You must log in or register to reply here.

Similar threads

U
Different neck tension and seating depth from round to round
Replies
18
Views
547
ma smith
ma smith
T
Seating Depth / Lands Measurement Way Off?
Replies
9
Views
189
_Thor_
T
A
Please help with seating issues
Replies
8
Views
353
918v
918v
Max_The_Phoenix
load development seating depth question
Replies
18
Views
1K
ShtrRdy
ShtrRdy
B
Im a novice and need direction
Replies
16
Views
598
fpgt72
fpgt72
Top Bottom
Back
Home
Forums
Merch
Alerts