Why loaded rounds vary with base to ojive?

sig2009

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So I'm reloading some 6.5 creedmoor with 140gn RDF and Hornady brass with the Forster Ultra micrometer seating die on an RCBS Rockchucker. Before loading I measure each bullet from base to ojive. So for example all are .784. Now my loaded round I want to be .050 off lands which gives me a measurement in my rifle of 2.236. Now I set up the first round and get the micrometer set to seat to 2.236. Next bullet I seat it may be 2.250. Next could be 2.245. Why then if I set up the first round to seat at the depth I want, the next ones are no where near that measurement? It seams every bullet I seat I have to check and reset the seater die?
 

Juggerxxx

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The primer is sticking out slightly slightly past the base? Use a pocket uniformer for a deeper pocket?

the tip of the bullet is touching the seating stem in the fosters?
 

MtnCreek

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^ I'd also suspect the bullet bottoming out in the seating stem.

Measure the same cartridge several times to rule out inconsistent measuring on your part.
 

JoeBUtah

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Along the same lines as what Juggerxxx is suggesting, are all of your case as the same (trim to) length? Do you have a case comparator to measure shoulder bump ( or non-bump)? If all your bullets spec the same, it would seem your variations point to the cases.

I've never used a micro adjustment seater die, but I always kind of figured that you seat each bullet by hand; that is set the die a little long, check your ogive length and then dial in down accordingly. Repeat for each round.
 

sig2009

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The primer is sticking out slightly slightly past the base? Use a pocket uniformer for a deeper pocket?

the tip of the bullet is touching the seating stem in the fosters?

No. Primers are seated slightly below where they should be.
 

sig2009

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The primer is sticking out slightly slightly past the base? Use a pocket uniformer for a deeper pocket?

the tip of the bullet is touching the seating stem in the fosters?

The Forster Ultra Micrometer seating die seats on the ojive and not the tip.
 

lash

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Case length variations should have nothing to do with the seating depth of the bullet and he should not have to to adjust down for every bullet seating. He has something else going on in his press or seating process that is introducing this large of a variation. It is not uncommon to see a 0.002-0.005" total variation.in seating depth, which I consider acceptable for all but my most picky ELR rounds. But 0.014-0.015" is a bit more than should be happening if everything is set properly.

OP, is your load by chance a packed load where you might be getting some back pressure from an over capacity powder charge? I've seen variations in BTO lengths in those cases. Then, a good vibratory table or other vibration is helpful to settle the powder charge down a bit before seating.
 

lash

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The Forster Ultra Micrometer seating die seats on the ojive and not the tip.

Yes, that is the design, but sometimes, when using a bullet with an extra long sharp tip, the ogive is low enough that the tip of the bullet can contact the seating die top. The RDFs are that type of bullet.
The fix for that is a simple bit of machining touch-up of the seating stem. It's not that uncommon.

I'm not saying that is his problem, but it could be. Only he can find that out.
 

sig2009

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Case length variations should have nothing to do with the seating depth of the bullet and he should not have to to adjust down for every bullet seating. He has something else going on in his press or seating process that is introducing this large of a variation. It is not uncommon to see a 0.002-0.005" total variation.in seating depth, which I consider acceptable for all but my most picky ELR rounds. But 0.014-0.015" is a bit more than should be happening if everything is set properly.

OP, is your load by chance a packed load where you might be getting some back pressure from an over capacity powder charge? I've seen variations in BTO lengths in those cases. Then, a good vibratory table or other vibration is helpful to settle the powder charge down a bit before seating.

42 gn H4350 is the load.
 

sig2009

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Yes, that is the design, but sometimes, when using a bullet with an extra long sharp tip, the ogive is low enough that the tip of the bullet can contact the seating die top. The RDFs are that type of bullet.
The fix for that is a simple bit of machining touch-up of the seating stem. It's not that uncommon.

I'm not saying that is his problem, but it could be. Only he can find that out.

Interesting. I never thought of that. But also next time I will measure the lengths of each bullet and get as close to the same length before I reload them and see what happens then.
 
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lash

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If your bullet tips are hitting the top of your seating die, you should be able to notice an ever so slight deformation of the bullet tip or at least a shiny spot at the tip, where it is hitting.

If it turns out that this actually is a problem with your bullets hitting the top of the die, call Forster. Usually, they will fix their die to eliminate the condition as long as you are willing to ship it to them.
 

Juggerxxx

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This will make no sense to you as it also makes no sense to me but, I have found inconsistent neck tension will cause the bullet to seat at varying depths.
 

lash

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This will make no sense to you as it also makes no sense to me but, I have found inconsistent neck tension will cause the bullet to seat at varying depths.

This actually makes sense to me. I am such a believer in consistent neck tension that I neck size after full length sizing. Seems time wasteful, but I get consistent low ES/SD this way, so...

I also anneal every other firing for the same reason.
 

mrbig

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The primer is sticking out slightly slightly past the base? Use a pocket uniformer for a deeper pocket?

the tip of the bullet is touching the seating stem in the fosters?

on some of the VLD type bullets with very long noses the tip of the bullet can make contact on the tip in the bottom of the seater stem and if the overall length of the bullet is .020 longer than the last one it will be seated ,020 deeper than the last one,,,you should be able to use a small drill bit and drill the seater stem so all the bullets can make contact at the same place on the sides of the bullet insteadof at the tip
 

sig2009

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This actually makes sense to me. I am such a believer in consistent neck tension that I neck size after full length sizing. Seems time wasteful, but I get consistent low ES/SD this way, so...

I also anneal every other firing for the same reason.

All neck Sized with a .288 bushing..
 

Brux

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Seems like your bullets are seating off the tips of the bullets and not the ogive and a inconsistency in bullet length is giving you these problems.
Take your seating die apart,take a bullet and push it up in the seating stem and see if the tip of the bullet hits before the ogive makes contact with the seating stem,if so theres your problem.
 

getoffmylawn

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Yes, that is the design, but sometimes, when using a bullet with an extra long sharp tip, the ogive is low enough that the tip of the bullet can contact the seating die top. The RDFs are that type of bullet.
The fix for that is a simple bit of machining touch-up of the seating stem. It's not that uncommon.

I'm not saying that is his problem, but it could be. Only he can find that out.

This is a pretty solid thought. I've had similar issues, not as much variation, but upwards of .010. This is with seating 147 gr eld/m. I will definitely be looking into this as a possible cause. Thanks!
 

gunsnjeeps

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Stepping in late. The seater is designed to seat from the ogive. If you have a high bc bullet the tip can touch the seater before the ogive. It doesn't matter what you measure where, it doesn't fix this. Take your seating stem out of the die and place a bullet in it and look at it. Does the bullet hit at the tip or the ogive?

The seating die doesn't reference from the case neck just the rim. If you hitting the tip not the ogive you will have the same overall measurement but different ogive measurements.

Hope this helps.
 

gunsnjeeps

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PS: Sometimes you will see a ring around the ogive if the stem is a sharp angle. This is easily fixed by lapping the edge of the stem with a bullet. I haven't seen any problems buy some folks worry about it.
 

jsthntn247

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Not one seater on the market today seats off the ogive. Measure where your seater makes contact on the bullet and it won't be bullet diameter. If the bullet has inconsistencies from the ogive to where the seater makes contact you are going to have varying seating depths. Bob Green makes a comparator to sort bullets that solves this. Also if your neck tension varies much you will have seating inconsistency.
 

Jig Stick

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its variation in your bullet jackets. I seat bullets using Wilson Inline Seater dies with VLD stems in them. With an arbor press. And I get 0.002-.005 variation between lots of Berger VLDs all the time. It will drive you absolutely nuts trying to be consistent with a Micrometer seater. Unless you decide to start using a comparator and sort bullets into lots I think you may be chasing your tail. I know you aren't dealing with Berger bullets, but I suspect hornady bullets would be even worse. The jackets on the AMAX were notoriously inconsistent.
 

sig2009

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its variation in your bullet jackets. I seat bullets using Wilson Inline Seater dies with VLD stems in them. With an arbor press. And I get 0.002-.005 variation between lots of Berger VLDs all the time. It will drive you absolutely nuts trying to be consistent with a Micrometer seater. Unless you decide to start using a comparator and sort bullets into lots I think you may be chasing your tail. I know you aren't dealing with Berger bullets, but I suspect hornady bullets would be even worse. The jackets on the AMAX were notoriously inconsistent.

I am sorting the RDF with a comparator. And No. The Hornady bullets are better consistency seating for me.
 

atefft22

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I too had issues with the Rdf in .243 though 105gr. Had larger seating variances then I liked. The berger 105 was within 3 thou or so. Was using in 6 dasher with bushing sized and anealed 3xfired. Seated with forster micrometer. My thought was inconsistent bullet shape and the long point of rdf contacting the stem. I just long seated and grouped them and ran em 1 more time to uniform depth. .... I may have had the same issue with the 140 rdf in my 6.5x47. The rdf shot 2x bigger groups then the berger in both rifles. fwiw won't be using rdf again.
 

JePhyllis

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Seems like your bullets are seating off the tips of the bullets and not the ogive and a inconsistency in bullet length is giving you these problems.
Take your seating die apart,take a bullet and push it up in the seating stem and see if the tip of the bullet hits before the ogive makes contact with the seating stem,if so theres your problem.

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