Inconsistent seating depth

[Oldmauser]

Today, I came across the following problem. I was preparing two control sets of bullets in 6.5 CM consisting of 11 bullets each: (Group no. 1) Lapua brass: (1)shoulders bumped 2 thau with Redding body die, then (2) 3/4 of the neck sized with Redding Competition neck sizing die using .290 bushing, (3) neck expanded using 21st century carbide mandrel, (4) bullets seated using Forster micrometer seating die, (Group no. 2) Lapua brass: (a) FL sized using Forster FL sizing die WITHOUT rod, (b) neck expanded using 21st century carbide mandrel, (c) bullets seated using Forster micrometer seating die.

Before seating the bullets, I measured the sized brass: headspace and neck diameter were identical in both groups. I noticed that in Group no. 2 I had to put more force to run the carbide mandrel through the neck. Probably Forster FL die squeezed the necks more than Redding competition neck sizing die with .290 bushing.

After seating bullets in both groups I measured CBTO in both groups. In group no. 1 the difference was about 4 thau- I have CBTO stretching from 2.214 up to 2.218, averaging 2.215 cbto. In group no. 2 I have maximum 2thau difference in CBTO: 2.215- 2.217.

Lapua brass was not annealed this time, there could be the case that some brass was 2 times fired, another piece of brass was fired 3 times.

So, brass is a major variable in our equation. What are the correct conclusions to be drawn from this in your view?

 

[nn8734]

The major variable seems to be the fact you used two different sizing dies for each group.

shouldn’t one of those groups be the control group the other one be the experimental differentiated presumably by the sizing die(s) used?

What were the neck diameters of each group of brass before the mandrel but after the sizing itself? Maybe that’s where the difference in neck tension lies?

ETA; did you Ogive sort those bullets into groups before you did the seating? (Note: if you’re jumping more than say .030” .004” variance won’t make any real difference in terms of the groups)

 

[AllenOne1]

Send your Forster die back to Forster and have the neck reamed out to .288, full length size your brass every time, use the mandrel and then seat your bullet with the Forster seater. Throw the Redding dies away and don't look back. I would recommend annealing the brass every time.

As far as your CBTO variation my guess is that more lube is getting scraped off using the Forster sizing die but it is causing a more consistent bullet push, seems backward but you may be ending up with a more consistent amount of lube inside the neck. If you are sizing to .290 with your neck sizer you don't have much neck tension when seating the bullet and should have little or no tension on the mandrel.

 

[Oldmauser]

The major variable seems to be the fact you used two different sizing dies for each group.

shouldn’t one of those groups be the control group the other one be the experimental differentiated presumably by the sizing die(s) used?

What were the neck diameters of each group of brass before the mandrel but after the sizing itself? Maybe that’s where the difference in neck tension lies?

It was main purpose of this excercise- to use 2 different set of dies. The necks were .285 and .287 respectively.

 

[AllenOne1]

Your .290 bushing is sizing you down to .287?

 

[whatsupdoc]

The Forster die reduced the neck to a smaller diameter than the .290 bushing die so the mandrel most likely expanded the
Forster sized neck but probably did not do anything to the bushing sized neck.

What is the diameter of the mandrel? If I use a .290 bushing and a turning mandrel to expand 6.5 Lapua brass the mandrel
does not expand the neck.

You also stated (as I understand it) that you only sized 3/4 of the neck with the bushing, why ?

There is also the load on the press, the amount of pressure (resistance of the bullet in the case neck) required to seat the
bullet will affect the seating depth. Usually the higher the pressure the longer the CBTO by a few thousands.

Whjy use brass fired 2x and 3x unless that is what you are looking to test?

 

[Gregor.Samsa]

I chased my tail with this as well for a while. My resolution was to anneal every loading, mandrel expand and lube the case necks with graphite. The graphite is messy but the combination of all these measures have really gone a long way to make my neck tension much more consistent.

 

[XLR308]

It was main purpose of this excercise- to use 2 different set of dies. The necks were .285 and .287 respectively.

Sounds like your overworking the brass, i use a .289 bushing with mine and yields .002" of tension.
I also turn my lapua brass for approximately 90% clean up.

 

[AllenOne1]

I chased my tail with this as well for a while. My resolution was to anneal every loading, mandrel expand and lube the case necks with graphite. The graphite is messy but the combination of all these measures have really gone a long way to make my neck tension much more consistent.

Are you measuring bullet seating pressure to determine the seating consistency or just going by feel on the press handle. I have been using the press handle method which is probably not ideal.

 

[nn8734]

It was main purpose of this excercise- to use 2 different set of dies. The necks were .285 and .287 respectively.

You haven’t explicitly stated the main purpose (the methodology/approach was using two different dies) but I’m assuming it’s to develop a load that can perform optimally in a F-class environment (ie reduce the ammo to as much of a constant as humanly possible so that it’s not the weakest link.

I was just wondering if you had track record with one of the sizing dies (Redding or Forster) and wer experimenting with the other to see if you can improve the load’s consistency. Hence control group and experimental group.

Glad you answered my question about neck diameter post sizing, pre mandrel.

@whatsupdoc found one of the main drivers behind your observations (see first paragraph of his response).

 

[Gregor.Samsa]

Are you measuring bullet seating pressure to determine the seating consistency or just going by feel on the press handle. I have been using the press handle method which is probably not ideal.

I am only using a Forster seating die on a rockchucker, nothing scientific. The feel is by far more consistent and I'm within .002" or less in CBTO over 100 rounds loaded. before, my spread could be up to .005" which was really frustrating.

 

[Baron23]

Am I missing something here. Diff in CBTO was .002”, right?

and this is concerning?

I believe a human hair is about 3-7 thousands and the throat is supposedly eroding more than .002” for every 100 rounds.

I’m not trying to be snarky, just trying to understand the import of .002” of CBTO to any practical consideration.

cheers

 

[Gregor.Samsa]

Am I missing something here. Diff in CBTO was .002”, right?

and this is concerning?

I believe a human hair is about 3-7 thousands and the throat is supposedly eroding more than .002” for every 100 rounds.

I’m not trying to be snarky, just trying to understand the import of .002” of CBTO to any practical consideration.

cheers

I'm stoke to get it down within a variance of a couple thou. I was previously struggling with this measurement being far more inconsistent. I'm not a great shooter, but it's a boon to be able to rule out as many variables as possible

 

[KnowNothing256]

I haven’t seen you mention which bullets you’re using, and if I missed it sorry but I didn’t see a response to the question asking if you ogive-sorted the bullets first.

I see three potential sources of your complaint, based on your description so far:
1) Inconsistent bullets. Did you sort them by (or at least check) BTO measurement?
2) Improper seater die setup. The micrometer die should bottom out when the bullet is fully seated to the desired depth, none of this “quarter turn out” crap people do with their sizing dies. I’m guessing this isn’t your problem, but please verify that you’re bottoming out the seater die.
3) If the bottom of the bullet bearing surface is right at the neck/shoulder junction, even a mild donut could be pushing the bullet back out unpredictably. I think this would only be a problem in your FL-sized cases though, since you’re specifically trying to avoid this issue by using the Redding die and stopping short of sizing that zone, and it’s the Redding cases that are unsatisfactory. So, I don’t think this is your issue.

I think it’s your bullets, based on what we know so far. Key question: is the bottom of the bearing surface above the neck/shoulder junction? If not, the other potential is variable neck tension, and the Forster die or neck turning plus bushing die are your fixes for that.

 

[Baron23]

I'm stoke to get it down within a variance of a couple thou. I was previously struggling with this measurement being far more inconsistent. I'm not a great shooter, but it's a boon to be able to rule out as many variables as possible

Hi Gregor - I was referring to the OP.

I do think he said he was fretting (my word, not his) over a .002 delta between his two sets

 

[Gregor.Samsa]

Gotcha!! Sorry to
Hijack

 

[Steel head]

OP
What are using to measure you base to ogive?
The Hornandy tool?
I found that boring out or making my own insert to measure at the actual area a bullet contacts the lands instead of the silly small for caliber Hornandy inserts your going to get a better picture of the situation.

I found a .259-.261 diameter insert works well for 6.5’s and bullet are often a lot more consistent in that area than further up the nose.

 

[Oldmauser]

Your .290 bushing is sizing you down to .287?

my bad- .297.

 

[Oldmauser]

Send your Forster die back to Forster and have the neck reamed out to .288, full length size your brass every time, use the mandrel and then seat your bullet with the Forster seater. Throw the Redding dies away and don't look back. I would recommend annealing the brass every time.

As far as your CBTO variation my guess is that more lube is getting scraped off using the Forster sizing die but it is causing a more consistent bullet push, seems backward but you may be ending up with a more consistent amount of lube inside the neck. If you are sizing to .290 with your neck sizer you don't have much neck tension when seating the bullet and should have little or no tension on the mandrel.

I am based in Europe. I would wait for my Forster die to send back about 6 months. Otherwise, it's a good idea.

 

[Oldmauser]

The Forster die reduced the neck to a smaller diameter than the .290 bushing die so the mandrel most likely expanded the
Forster sized neck but probably did not do anything to the bushing sized neck.

What is the diameter of the mandrel? If I use a .290 bushing and a turning mandrel to expand 6.5 Lapua brass the mandrel
does not expand the neck.

You also stated (as I understand it) that you only sized 3/4 of the neck with the bushing, why ?

There is also the load on the press, the amount of pressure (resistance of the bullet in the case neck) required to seat the
bullet will affect the seating depth. Usually the higher the pressure the longer the CBTO by a few thousands.

Whjy use brass fired 2x and 3x unless that is what you are looking to test?

1. I use standard 21 Century carbide mandrel for 6.5 mm cartridge, not oversized or undersized. the standard one.
2. I size 3/4 of the neck because more experience f-class colleagues say that get better results if the size only portion of the neck.
3. Yes, the brass is the weak point of the test. I simply did not have fresh brass. The same refers to my annealer which just crushed. I have to replace some parts in this machine.

 

[Oldmauser]

I chased my tail with this as well for a while. My resolution was to anneal every loading, mandrel expand and lube the case necks with graphite. The graphite is messy but the combination of all these measures have really gone a long way to make my neck tension much more consistent.

I usually do that. But since I was running the carbide mandrel I decided to skip this step. btw, are you cleaning the inside of the neck before seating bullets in this case or you leave the graphite inside?

 

[Oldmauser]

I was just wondering if you had track record with one of the sizing dies (Redding or Forster) and wer experimenting with the other to see if you can improve the load’s consistency. Hence control group and experimental group.


@whatsupdoc found one of the main drivers behind your observations (see first paragraph of his response).

Exactly this is the point. I have track record with Forster but since many top F-class champs use the following set: Redding body die+Redding neck sizing die, I decided to give it a try. People can talk for hours how important that is to separate bumping shoulders from neck sizing. Don't argue if this is the case. Just decided to give it a try. I will be testing both groups at the range tomorrow.

 

[Oldmauser]

I haven’t seen you mention which bullets you’re using, and if I missed it sorry but I didn’t see a response to the question asking if you ogive-sorted the bullets first.

I see three potential sources of your complaint, based on your description so far:
1) Inconsistent bullets. Did you sort them by (or at least check) BTO measurement?
2) Improper seater die setup. The micrometer die should bottom out when the bullet is fully seated to the desired depth, none of this “quarter turn out” crap people do with their sizing dies. I’m guessing this isn’t your problem, but please verify that you’re bottoming out the seater die.
3) If the bottom of the bullet bearing surface is right at the neck/shoulder junction, even a mild donut could be pushing the bullet back out unpredictably. I think this would only be a problem in your FL-sized cases though, since you’re specifically trying to avoid this issue by using the Redding die and stopping short of sizing that zone, and it’s the Redding cases that are unsatisfactory. So, I don’t think this is your issue.

I think it’s your bullets, based on what we know so far. Key question: is the bottom of the bearing surface above the neck/shoulder junction? If not, the other potential is variable neck tension, and the Forster die or neck turning plus bushing die are your fixes for that.

Thank you Sir for bringing to the table new crucial variables.
1. No. I did not sort the bullets. I had this idea but decided to put my faith in Berger's propaganda. I was seating 140gr Hybrid Targets.
2. I think the seating die setup is ok.

 

[Oldmauser]

OP
What are using to measure you base to ogive?
The Hornandy tool?
I found that boring out or making my own insert to measure at the actual area a bullet contacts the lands instead of the silly small for caliber Hornandy inserts your going to get a better picture of the situation.

I found a .259-.261 diameter insert works well for 6.5’s and bullet are often a lot more consistent in that area than further up the nose.

yes, I was using the hornady tool. I was using insert no. 5 if I remember correctly.

 

[nn8734]

Thank you Sir for bringing to the table new crucial variables.
1. No. I did not sort the bullets. I had this idea but decided to put my faith in Berger's propaganda. I was seating 140gr Hybrid Targets.
2. I think the seating die setup is ok.

How far are you jumping your 140’s ?

 

[Snuby642]

A question I have not seen asked.

Are you running compressed loads?

 

[Snuby642]

I had problems with seating depth on compressed loads and tapped and vibrated the cases as best I could to help with that.

 

[Dthomas3523]

Just from skimming the post:

1: different initial sizing dimensions + the same mandrel will typically induce different spring back. Pin gauges would highlight this

2: mixed amount of firings + not annealed

 

[Oldmauser]

A question I have not seen asked.

Are you running compressed loads?

Nope. No compressed loads.

 

[Oldmauser]

How far are you jumping your 140’s ?

Somewhere between 15-20 thau.

 

[Oldmauser]

Just from skimming the post:

1: different initial sizing dimensions + the same mandrel will typically induce different spring back. Pin gauges would highlight this

2: mixed amount of firings + not annealed

This is my hypothesis. I have to buy a 200$ replacement part for my annealing machine and hopefully my sds go down and I finally get back to consistent neck tension.

 

[Gregor.Samsa]

I usually do that. But since I was running the carbide mandrel I decided to skip this step. btw, are you cleaning the inside of the neck before seating bullets in this case or you leave the graphite inside?

I’m only doing a light tumble in walnut shell prior to annealing. I then FL size, mandrel expand, prime, dip in graphite coated shot, charge with powder and seat the bullet. Nothing fancy

 

[Deleted member 10043]

Today, I came across the following problem. I was preparing two control sets of bullets in 6.5 CM consisting of 11 bullets each: (Group no. 1) Lapua brass: (1)shoulders bumped 2 thau with Redding body die, then (2) 3/4 of the neck sized with Redding Competition neck sizing die using .290 bushing, (3) neck expanded using 21st century carbide mandrel, (4) bullets seated using Forster micrometer seating die, (Group no. 2) Lapua brass: (a) FL sized using Forster FL sizing die WITHOUT rod, (b) neck expanded using 21st century carbide mandrel, (c) bullets seated using Forster micrometer seating die.

Before seating the bullets, I measured the sized brass: headspace and neck diameter were identical in both groups. I noticed that in Group no. 2 I had to put more force to run the carbide mandrel through the neck. Probably Forster FL die squeezed the necks more than Redding competition neck sizing die with .290 bushing.

After seating bullets in both groups I measured CBTO in both groups. In group no. 1 the difference was about 4 thau- I have CBTO stretching from 2.214 up to 2.218, averaging 2.215 cbto. In group no. 2 I have maximum 2thau difference in CBTO: 2.215- 2.217.

Lapua brass was not annealed this time, there could be the case that some brass was 2 times fired, another piece of brass was fired 3 times.

So, brass is a major variable in our equation. What are the correct conclusions to be drawn from this in your view?

The average difference is immaterial. Also, group #2 is more consistent. I love these one off scientific experiments. There is no correct conclusion, which is what you are asking. Not even sure why you are asking. I take it that you haven't shot them yet. So, we don't know how the two groups performed on target.

 

[918v]

Today, I came across the following problem. I was preparing two control sets of bullets in 6.5 CM consisting of 11 bullets each: (Group no. 1) Lapua brass: (1)shoulders bumped 2 thau with Redding body die, then (2) 3/4 of the neck sized with Redding Competition neck sizing die using .290 bushing, (3) neck expanded using 21st century carbide mandrel, (4) bullets seated using Forster micrometer seating die, (Group no. 2) Lapua brass: (a) FL sized using Forster FL sizing die WITHOUT rod, (b) neck expanded using 21st century carbide mandrel, (c) bullets seated using Forster micrometer seating die.

Before seating the bullets, I measured the sized brass: headspace and neck diameter were identical in both groups. I noticed that in Group no. 2 I had to put more force to run the carbide mandrel through the neck. Probably Forster FL die squeezed the necks more than Redding competition neck sizing die with .290 bushing.

After seating bullets in both groups I measured CBTO in both groups. In group no. 1 the difference was about 4 thau- I have CBTO stretching from 2.214 up to 2.218, averaging 2.215 cbto. In group no. 2 I have maximum 2thau difference in CBTO: 2.215- 2.217.

Lapua brass was not annealed this time, there could be the case that some brass was 2 times fired, another piece of brass was fired 3 times.

So, brass is a major variable in our equation. What are the correct conclusions to be drawn from this in your view?

If you are measuring cbto with an imprecise tool then you cannot reach a conclusion.

First, cbto consistency is overrated. If you develop the load correctly then you will find the node broad enough to dwarf a .004” difference.

Second, I’m guessing your caliper is not accurate enough to take consistent cbto readings.

Third, your handling of the cartridge within the adapter may be causing a variance in the readings.

 

[Oldmauser]

If you are measuring cbto with an imprecise tool then you cannot reach a conclusion.

First, cbto consistency is overrated. If you develop the load correctly then you will find the node broad enough to dwarf a .004” difference.

Second, I’m guessing your caliper is not accurate enough to take consistent cbto readings.

Third, your handling of the cartridge within the adapter may be causing a variance in the readings.

guessing does not lead our discussion anywhere, but I do appreciate your concern.

 

[918v]

guessing does not lead our discussion anywhere, but I do appreciate your concern.

Do you know the actual accuracy of your calipers? Unless they are certified, they are accurate to +\- .001” and you are trying to measure your cbto in .001” increments.

Your numbers are useless if you can’t be confident in your instruments.

 

[Snuby642]

Lets all send our calipers to the metrology lab every six months to get a little sticker. Lol

Or buy a piece of precision ground tool steel to check it on at will.

You can't assume everyone has calipers that suck, they can't use thier tools properly or that they are too stupid to get the process.

Even if calipers were off by 2 thousands as long as they were used to measure everything it would not be a game breaker.

Get a piece of tool steel and get on with it.

 

[918v]

That wasn’t the point.

If he is trying to measure cbto of 2.215” and his bullets induce a variance of +\-.001” then he will end up with 2.214” 2.215” and 2.216” long cartridges, actually.

If he takes his piece of shit caliper and measures the shortest round it may give a 2.213” reading or 2.215” reading. The longest reading could be 2.217” or 2.215”. Or all of them could read 2.215”.

It could very well be that he does not have any difference between his two groups.

 

[nn8734]

That wasn’t the point.

If he is trying to measure cbto of 2.215” and his bullets induce a variance of +\-.001” then he will end up with 2.214” 2.215” and 2.216” long cartridges, actually.

If he takes his piece of shit caliper and measures the shortest round it may give a 2.213” reading or 2.215” reading. The longest reading could be 2.217” or 2.215”. Or all of them could read 2.215”.

It could very well be that he does not have any difference between his two groups.

If he (or anyone) has 10 rounds with exactly the same CBTO of 2.215” and then 10 rounds where there is a range of .004” in total variance, centered on 2.215” (min: 2.213 and max 2.217”) AND he’s jumping between .018”and .022” with the second group ——- do you think he’s going to see a material difference on paper at 100m and/or muzzle velocity consistency between the two test groups?

For added context, Let’s assume his neck tension, ch-shoulder and seating force are all held constant with no variation anywhere on those two samples to eliminate tolerance stacking (highly unlikely but for sake of argument, let’s say they are).

Let’s also hold that he used the same sizing die set up to make these hypothetical rounds.

 

[918v]

No difference on paper or in velocity.

Nodes are wide enough to mitigate the variance. That’s why they are called nodes.

 

[acudaowner]

goofer dust , black magic need to sacrifice a chicken or two

just to ask have you trimmed your cases ? or at least checked the length on all the cases and the bullets ?good luck figureing out what your problem is at least with the chicken you can eat it while you figure out what ever it is .

 

[nn8734]

No difference on paper or in velocity.

Nodes are wide enough to mitigate the variance. That’s why they are called nodes.

I didn’t mention anything about nodes, the question wasn’t whether nodes were wide enough to mitigate.

In your opinion, would the stated variance represent a material difference in mv and on paper, regardless of whether the charge weight is in a node or not?

Or is your previous opinion contingent on the CW being in the rifle’s node?

 

[918v]

Zero effect on speed regardless of cw.

 

[nn8734]

Zero effect on speed regardless of cw.

So if the caliper variance has zero effect on speed and presumably the rifle’s performance on paper at 100m (and by extension all the way through the round’s supersonic envelope), do you still think calipers (the OP’s or whomever’s) should be periodically sent in for calibration or certified for accuracy , as you mentioned in post #36, if the caliper set’s potential error is .004” or less?

 

[918v]

Please read post#34

 

[nn8734]

Please read post#34

To be clear, your answer is “No” - correct?

 

[918v]

Correct.

My two cents was to address the perceived difference between the two groups of ammo assembled using different means.

 

[nn8734]

Copy that, thanks @918v

 

[Snuby642]

That wasn’t the point.

If he is trying to measure cbto of 2.215” and his bullets induce a variance of +\-.001” then he will end up with 2.214” 2.215” and 2.216” long cartridges, actually.

If he takes his piece of shit caliper and measures the shortest round it may give a 2.213” reading or 2.215” reading. The longest reading could be 2.217” or 2.215”. Or all of them could read 2.215”.

It could very well be that he does not have any difference between his two groups.

You are just an argumentative shit head.

No solutions just trolling bullshit.

Flush botton in 3-2-1 se ya.

 

[918v]

Sorry but the toilet’s clogged