**WHY do my seating depths vary so much???

[jcvibby]

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?

 

[geordiesniper]

Hi, if your measuring the loaded round from headstamp to bullet tip then the difference you have noticed is most likely to be because your bullets have different overall lengths, and thus each overall length of your loaded rounds will differ by a few thou or 5. To get a true reading you need to measure from headstamp to ogive with a bullet comparitor on a loaded round. By measuring this way it will give you a more consistent measurement.
Try it and see what happens.

 

[NorCalMikie]

Are your bullets tips bottoming out and touching in the seater stem?

 

[Shynloco]

Hi, if your measuring the loaded round from headstamp to bullet tip then the difference you have noticed is most likely to be because your bullets have different overall lengths, and thus each overall length of your loaded rounds will differ by a few thou or 5. To get a true reading you need to measure from headstamp to ogive with a bullet comparitor on a loaded round. By measuring this way it will give you a more consistent measurement.
Try it and see what happens.

Big +1. Ojive measurement is the only reliable measuring for maintaining consistency in bullet seating depths. IMHO, OAL measurements are worthless for best accuracy. Good luck!

 

[spclark]

Once you've changed your habit to measuring from the land-contact point method as others suggest, the next variable is neck tension. Reloading presses give us tremendous mechanical advantage when sizing and reloading cartridges so you need to be sensitive to how much force you're using on the press ram when seating bullets. Consistency is the goal but at the same time more or less neck tension will influence the depth to which bullets are being seated.

I started in with neck & shoulder annealing just for this reason, when I noticed not only what you're seeing despite my measuring from the bullet ogive, but also inconsistent shoulder set-back with a given sizing die position.

Of course base to land-contact diameter consistency of the bullets you use matters too but as you mentioned JLK's I doubt that's a factor for you. Steve Milholland's bullets are some of the most dimensionally consistent available.

It all adds up in the end....

 

[jcvibby]

I just bought the Hornady tool for my caliper. We will see what that says.

 

[DHD]

When I measure OAL, max mag length is 2.825", I notice what you have seen. This is with Bergers, SMK's, Scenars, well you get the picture. I just seated some 175 NCC's, and it was terrible from head to tip, but from head to ogive was good.

When I use the tool you just purchased, they are very close to the same. I also use Forster seating dies and I seat with a nice smooth consistant motion. I have little doubt you will see those numbers settle down to +/- .002ish.

 

[Link]

Before I got a ogive block I used a fired case.

Don't know why that won't work in a pinch. // ??

Link

 

[jcvibby]

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

 

[necchi]

Actually it's just the nature of the machine that makes'm.
The effort in the Pointing process focuses on consistant diameter and ogive to make a better bullet.
It's easy for us to get lost when looking at a dial or numbers as they display and forget to look at how much .007 really is as distance from one jaw to another.

.007 as runout, or .007 as jam can make a big difference, but .007 in a point of a bullet ???

 

[halfmoanut]

My best advice to you would be this.Measure each and every bullet and keep each ogive length seperate in groups and when loading say in groups of 3,5,10 etc,etc,load only (one) length do not mix different lengths together.Only true custom bullets (Bibbs,Fowler,Barts) etc,etc are more consistent and from lot to lot they will vary somewhat also. A good lot of bullets will only have (3) different lengths per 100 and will only vary .005.And on the flip side of the coin a good barrel will shoot many different lengths exceptionally well mixed together,however when you reach beyond 400yds is when variables in reloading components and reloading technique go south.

 

[spclark]

Before I got a ogive block I used a fired case.

Don't know why that won't work in a pinch. // ??

It will, Link! In fact just about anything with a proper-size hole on one side with a flat side opposite will work. Folks made their own this way for many years before somebody "invented" a dedicated tool! If you're savvy you can have your gunsmith make a tool from the cut-off waste of a new barrel using the same reamer as that barrel's chamber. This is by far the BEST thing to use because it matches your chamber exactly and can tell you how far your throat erodes & how fast.

 

[dennisinaz]

Once you've changed your habit to measuring from the land-contact point method as others suggest, the next variable is neck tension. Reloading presses give us tremendous mechanical advantage when sizing and reloading cartridges so you need to be sensitive to how much force you're using on the press ram when seating bullets. Consistency is the goal but at the same time more or less neck tension will influence the depth to which bullets are being seated.

I started in with neck & shoulder annealing just for this reason, when I noticed not only what you're seeing despite my measuring from the bullet ogive, but also inconsistent shoulder set-back with a given sizing die position.

Of course base to land-contact diameter consistency of the bullets you use matters too but as you mentioned JLK's I doubt that's a factor for you. Steve Milholland's bullets are some of the most dimensionally consistent available.

It all adds up in the end....

That is simply not true. The ogive measurement is theoretically the best way, but a quality bullet like 130 JLKs will be very consistent in length.

I recently ran into this problem with 140 Berger Hybrids. I was getting .015" variance! I started lubing bullets and got it down to about .004-.005 variance.

I finally had to put a larger bushing in my die than I had ever used (quick trip across town to Brunos). I went with a .291 bushing and reduced the neck tension to a minimum. While I was at Brunos I bought the Sinclair comparator tool. I then started over (using the Forster BR seater) and now I was within .001 on all of them. I then measure tip-to-tip. It was within .001" as well. If your bullets are measuring much different from tip to tip as compared to the comparator measurement it is time to get new bullets that are made better.

Most likely, you have too much neck tension and your jackets are yielding to the end of the seater stem. Reduce the neck tension, clean the inside of your necks and lightly lube the bullet with wax before seating and your problem will almost certainly go away.

 

[spclark]

That is simply not true.

Which of the several statements I made do you disagree with? There was more than one, and after reading your comments I don't understand which of mine differs in any significant way from yours.

We seem to be in agreement about:

More neck tension = greater force needed to seat bullets, perhaps causing bullet jackets to deform at the point a seating stem bears against them;

Inconsistent neck tension = variations in seating depth owing to more or less friction opposing seating stem force;

I've never encountered the suggestion to lube bullets to reduce seating inconsistencies, other than when bullets have been waxed after moly-coating or from other bullet lubes being used to reduce friction and/or fouling in the bore.

When neck tension, interior neck surface, bullet jacket condition, seating force and bullet dimensions are all known and under control, uniform seating depth can be achieved without much effort.

That some brands and styles of bullets have a wider tolerance for length overall is one of the factors favoring custom bullets when available. Match bullets from premium suppliers will still have small variations in the meplats or tips, which is what leads some to the extra step of meplat-uniforming, perhaps even to be then followed by an additional "pointing-up." Custom bullets like Swampy's will show much less need for these kinds of operations but may still benefit from sorting to determine what minor variations are present.

It's a well-established practice to measure seating depth from the point on a given bullet where the intended rifle chamber's lands first come into contact, rather than from measuring from the frequently inconsistent meplat, when one seeks to load ammunition of the most uniform performance characteristics possible.

 

[hogan]

I dunno about no hornady tool...

What you want is a Sinclair Bullet Comparator. They make 2. These are Hexagon gizmos that are precision ground with 6 different holes on each side for varying bore diameters. Buy the one that matches the bore diameters you load for.

This tool is used with a dial caliper to show OAL from ctg base to ogive. You want your seating to be ogive determined. The Sinclair tool is exactly 1" so you subtract this amount from your dial caliper reading and you know your consistent load to dimension.

 

[in2deep]

As mentioned above if your using a Forster die the factory-determined neck size in the full-length die may be much smaller than needed for your precision bolt gun causing excessive seating force due to the neck deforming from the excess force needed to cram the bullet in the case.
Like the fellow above said next go round try lubing the bullets or inside necks with a common bullet/neck lube like Necco or Imperial neck lube and then measure for runout. Worked for me and found out my die was sized too small which is common and they will grind it out to your actual neck measurement for a small fee. When seating bullets in new brass I lube them also since the tension is really tight on virgin Lapua brass.

Or it could be something else but this is easy to check if your seating force is excessive and causing neck runout. If you don't use hand dies the amount of force a conventional press exerts is amazing and you may not even be able to discern even large amounts of resistance and brass is pretty soft and the neck is unsupported when the bullet is being forced down into it and it can easily bend causing runout.

 

[dennisinaz]

SPClark, I thought I was "quoting" what I wanted and somehow it clicked on you and it was not what I was wanting. The statement that I don't agree with is the one above your post..

VBig +1. Ojive measurement is the only reliable measuring for maintaining consistency in bullet seating depths. IMHO, OAL measurements are worthless for best accuracy. Good luck!

I do agree with what you said.

 

[tjtjwdad]

One thing to look for is check and make sure your primer isn't a little high. While not very likely, check the case head/face condition.

 

[spclark]

SPClark, I thought I was "quoting" what I wanted and somehow it clicked on you and it was not what I was wanting.

No problem. From what you'd written I figured we were in agreement.

 

[normmatzen]

Strange, but it seems no one has touched on the really most probable cause of cartridge length variation.

A friend and I both have Forster precision seaters bought about the same time.
Both of us had a hard time maintaining accurate lengths. I took to using a torque wrench as a press handle.
My friend in Australia ground the die's spring a bit shorter and with a flat end.

I copied him and length variation STOPPED!

Seems Forster used a wrong spring for a while and the spring set cartridge length. Once the spring was ground down a bit, the die itself set the length. End of problem!

We contacted Forster with our findings and they sent us both a new spring that was both shorter and weaker. Now not only can we expect 0.001 accuracy, we can feel the seating process with more accuracy.