Let’s talk load development

[Rimfire5]

Stagpanther,

I agree.
But even the same weight bullets from different manufacturers have different bullet lengths and ogive position, the bullet body lengths, and even the boat tail dimensions, so their relationship to the lands will be different with equal OALs and the amount of bullet body in the neck will be different.
All those dimensions have an effect on the pressure in the cartridge before the bullet leaves the neck and the muzzle velocity.
If you use the same OALs for the two different manufacturers, you are also changing the jump for each bullet and probably could effect the results.

In fact, I have started measuring the Bullet base to tip and base to ogive for each lot of bullets that I load, after I stumbled across a significant change in bullet dimensions when I tried a new lot of bullets that I regularly use.
The change in the length of a bullet changes the conditions for a load and, using the same load data for the new bullet size caused a measurable difference in the POI, and group size when I shot the new lot.

[Metal god]

TL , that’s a good point on the neck wall thicknesses . It would seem unreasonable for there to be a .010 variance with a case wall only .015 thick Keeping in mind I also have 3- 8’s and an 7 and those seem to be pushing it a bit as well .

Here’s a fun, interesting dilemma . I just sized that .010 case and one of the .001 cases , they both read .004 now

I should add I did not clean the brass other than wiping the outside, so the inside of the neck still have quite a bit of carbon and fouling which made pulling the expander button through a bit harder than usual .

Hmm that gets me thinking . Didn’t you say you don’t really clean your brass before loading it ? Does this mean you are seating your bullets into those dirty carbon filled case necks ?

why do you keep walking all over me?

Lmao , I don’t know if anybody saw that in my post above before I deleted it . I dictate a lot of of my posts and then go back and correct what it got wrong. But I missed that. The funny part is, I said that when my cat was walking over me. And somehow it got put into my post and I didn’t catch it. lol

[tangolima]

Originally Posted by Metal god

TL , that’s a good point on the neck wall thicknesses . It would seem unreasonable for there to be a .010 variance with a case wall only .015 thick Keeping in mind I also have 3- 8’s and an 7 and those seem to be pushing it a bit as well .



Here’s a fun, interesting dilemma . I just sized that .010 case and one of the .001 cases , they both read .004 now



I should add I did not clean the brass other than wiping the outside, so the inside of the neck still have quite a bit of carbon and fouling which made pulling the expander button through a bit harder than usual .



Hmm that gets me thinking . Didn’t you say you don’t really clean your brass before loading it ? Does this mean you are seating your bullets into those dirty carbon filled case necks ?







Lmao , I don’t know if anybody saw that in my post above before I deleted it . I dictate a lot of of my posts and then go back and correct what it got wrong. But I missed that. The funny part is, I said that when my cat was walking over me. And somehow it got put into my post and I didn’t catch it. lol

I don't clean the brass other than wiping the external carbon with clp. The only "cleaning" to inside of neck is applying graphite lube with q-tip. Since I don't have concentricity measurement setup, I just look the other way.

-TL

Sent from my SM-N960U using Tapatalk

[stagpanther]

If you had a bore scope (I know you're a conscientious objector ) and took a look inside a case--you might be surprised by what you see.

But even the same weight bullets from different manufacturers have different bullet lengths and ogive position, the bullet body lengths, and even the boat tail dimensions, so their relationship to the lands will be different with equal OALs and the amount of bullet body in the neck will be different.
All those dimensions have an effect on the pressure in the cartridge before the bullet leaves the neck and the muzzle velocity.
If you use the same OALs for the two different manufacturers, you are also changing the jump for each bullet and probably could effect the results.

In fact, I have started measuring the Bullet base to tip and base to ogive for each lot of bullets that I load, after I stumbled across a significant change in bullet dimensions when I tried a new lot of bullets that I regularly use.
The change in the length of a bullet changes the conditions for a load and, using the same load data for the new bullet size caused a measurable difference in the POI, and group size when I shot the new lot.

Pretty much what I think too, I'd add the freebore is a significant factor as well. My .257 "super" Weatherby shoots pretty much the same modern heavy .257 bullets as my 25 PRC--and really shines with Hornady's 134 gr ELDM. Try as I might, I haven't been able to get a really good load in my 25 PRC using the ELDM. Conversely, I haven't been able to get a Eureka load in my Weatherby using berger's 135 hybrid--but the 25 PRC loves them.

[Metal god]

It came to me in a dream last night . The question is how does a case neck that is only .015 thick have its concentricity off by .010 ? What if the entire neck is off-line to the center axis of the case body ?

[stagpanther]

It came to me in a dream last night . The question is how does a case neck that is only .015 thick have its concentricity off by .010 ? What if the entire neck is off-line to the center axis of the case body ?

I worry less about that than a barrel's concentricty of chamber/freebore/bore; brass is easier to move around.

[tangolima]

Originally Posted by Metal god

It came to me in a dream last night . The question is how does a case neck that is only .015 thick have its concentricity off by .010 ? What if the entire neck is off-line to the center axis of the case body ?

The bushing die should have "policed" the external dimensions back to spec. The expander ball would likely degrade that slightly, but should be nowhere by that much.

Could there be "unexpected" features on the brass body, such as a dent, that would affect the measurement results? Are the rollers in the gauge clean?

-TL

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[Metal god]

I was thinking about that . Years ago, I did some tests that showed that when you size down a case neck using the redding bushing dies a substantial amount meaning if you have a large generous chamber in the neck area. The result would be the case necks being sized down looking similar to an hourglass. It wasn’t a lot, but it was definitely there and in certain light very evident.

I posted about this many years ago . I even talked to Redding about it and they confirmed the issue and they suggested sizing down in two steps. Using a larger bushing then sizing again with the correct bushing. Which did actually work . However, what I had been doing is using the Lee collet neck die to decap my cases and while doing that sizing down my neck the first stage . I would then tumble and full length size using the correct bushing . I was doing this for a while , actually technically I still do it, but I haven’t actually sized any 308 cases since before the pandemic . I prep in very large lots 500+ sometimes 1000 and I have multiple lots. So it takes me a while to go through them all , I’m getting low in my Lake City 10 cases and I’m getting low on my Lapua. So case prep is coming soon.

Anyways when I use the collet neck sizing die, it leaves four little ridges where the little Collet spaces are . Maybe I’m not sizing those fully out with the bushing when I do the full length sizing . I’ll go do some quick sizing with the Collet die and see if I can show you what it does. It’s one of the reasons I don’t use it to size my neck. The other reason is it gives me two little bullet hold . Maybe I’ll do a video of me showing the concentricity. Of what the necks look like using the collet neck die .

[Metal god]

Lets see if this works

https://rumble.com/v6ueem7-lee-colle...entricity.html



I did not think to go ahead and full length size it in the video, but I did right after . The case neck run out after full length sizing was .002 so it definitely ironed out those ridges . I then seated a bullet and it’s run out was.003 . I went ahead and did one of the cases that when I started earlier, it was .008 off . The results were the same , virtually identical . Obviously this is a very, very small sample, but it is what it is.

[tangolima]

Originally Posted by Metal god

Lets see if this works



https://rumble.com/v6ueem7-lee-colle...entricity.html







I did not think to go ahead and full length size it in the video, but I did right after . The case neck run out after full length sizing was .002 so it definitely ironed out those ridges . I then seated a bullet and it’s run out was.003 . I went ahead and did one of the cases that when I started earlier, it was .008 off . The results were the same , virtually identical . Obviously this is a very, very small sample, but it is what it is.

Pretty cool. If you provide before and after seating run out figures, I will run the numbers. I think seating itself doesn't degrade concentricity much.

-TL

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[Metal god]

My question is those ridges after the Collet die jump about .004 does that mean there’s an .008 variance because there’s a jump of .004 and then you turn the case 180° and there’s another jump of .004 ?

[tangolima]

Originally Posted by Metal god

My question is those ridges after the Collet die jump about .004 does that mean there’s an .008 variance because there’s a jump of .004 and then you turn the case 180° and there’s another jump of .004 ?

The ridges shouldn't be taken as run out. Unless they are ironed out, they should be excluded from the measurement, i.e. only the part of neck without the ridges should be measured. When the indicator needle jumps, you need to check to make sure the problem is not on a ridge. That's a lot of work I am afraid.

Neck turn and you will have no ridges.

-TL

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[Metal god]

They are little ridges you can feel them in your fingers when you spin the case . But I wouldn’t want to turn those out. Because the next time I use the collet die they’ll be there again. That result in me just trimming off those little sections each time actually thinning the wall in those areas. Because once the case is fired, it’s gonna stretch back out flat. Those areas that I trimmed that were ridges will now be thinner case walls. Correct ?

Those ridges are a direct result of the design of the die . There are little spaces in between four little sections of the collet . I’ll take a picture of my collet crimp die , It’s basically the same thing as the collet neck die .

Note those spaces in between each crimping section for lack of a better term allows those sections to close in on each other . The neck die does basically the same thing and the brass flows back into those open spaces creating those ridges as it’s pressed against the mandrel . I don’t think it’s a good idea to turn those ridges off the case neck ???? I could be wrong. Maybe that’s exactly what I should be doing.



Same thing pinched close

[tangolima]

I see. It is part of your routine brass prep. I thought have stopped using the collet. In that case, I'm afraid we can't measure run out accurately then.

-TL

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[stagpanther]

I have quite a few Redding S bushing FL sizing die sets--as if by sheer coincidence while I was sizing today the decap pin pulled out (irritating feature of that die IMO) and upon removing the decap rod I discovered that the threaded end that screws into the expander was bent out of alignment with the rest of the rod. I bet that would easily introduce run-out in case necks.

[stagpanther]

Not to change the subject from run-out--but I decided to try something different today after watching the Hornady video about developing loads.

For a new load for the 25 PRC I decided to try berger 135 hybrids--which have worked well with other powders in the 25 PRC--but using H1000. I seated the bullets to 2.91. This time I decided to skip the chronograph (ignorance is bliss, and I know a lot about ignorance) for new load development and shoot a 10 shot group for the charge weights. This was the very first charge of 56.4 grs at 353 yards (interesting chevron shape to the group--there was a variable left cross 5-10 mph).



In the video it sounded like Miles suggested something to the effect--if it's MOA or less in a 10 shot group at 200 yards--your job is done. I'm wondering if it's a waste (it does use up a lot of powder and bullets to do 10 shot groups for all the ladder charge weights; something I've never done before) to keep going. I'm also wondering if the group dispersion thing really is linear to distance--in other words should I be "confident" that groups at shorter ranges would automatically be better?

[Metal god]

That’s pretty impressive , did you shoot other charges .

[Metal god]

I had to see a lawyer today about some things, I need them to draw up . There’s about 25 pages in this document that just explains what each phrase and word means.

That got me thinking about the word I used when I say those cases have “ridges” on them after sizing with a collet neck die . They don’t actually have ridges. I mean they’re not sharp. They don’t appear to be steep. They don’t have an edge you can fall off of. So now I’m trying to think of the proper word for it. I first wanted to say speed bumps. Maybe short little mounds. Or bumps the length of the neck.

Anyways, that was it haha for some reason it was bothering me .

[stagpanther]

That’s pretty impressive , did you shoot other charges .

That was part of the "paradox" of shooting the 10 shot group for the ladder instead of a smaller group size--this was the first and lowest-end charge of the ladder I chose; so the temptation is to say the heck with it, I'm done--and save money--by not continuing with the rest of the ladder.

I bought a couple neck size competition dies--and soon thereafter bought one of Erik Cortina's "I neck size" T-shirts.

[stagpanther]

That got me thinking about the word I used when I say those cases have “ridges” on them after sizing with a collet neck die . They don’t actually have ridges. I mean they’re not sharp. They don’t appear to be steep. They don’t have an edge you can fall off of. So now I’m trying to think of the proper word for it. I first wanted to say speed bumps. Maybe short little mounds. Or bumps the length of the neck.

Can you post a picture of the "ridge" on the case neck? I'm having trouble connecting the dots as to what's going on--though in general brass is going to moving after firing--and any trimming is going to lessen the brass over time.

[Metal god]

Ok this turns out to be much worse then I thought although most of the bumps on the cases aren’t this bad ( hard to find with the naked eye ) this one I can see freely and zoomed in …… it’s atrocious . You can see how it bends the case mouth which means there’s no way the inside diameter can be concentric. So I went ahead and got my deburring chamfer tool out and gave it a spin on the inside of the neck . You can totally feel it bump over those spots ( thump thump thump ) as you turn it .




Thank god I gave up on the Lee collet neck die almost as soon as I got it . Although It does appear when I use it to deprime my cases then FL size with my bushing die those bumps iron out . I’m no longer going to use that die for anything.

Speaking of that , I have a Lee collet neck die for sale

[stagpanther]

It looks to me like neck sizing with a collet crimp die All my bushing dies have solid inserts for setting diameters.

[Metal god]

It’s not a crimp die it just works similarly to the crimp die they both use the collet method to squeeze down the neck . The collet crimp die pinches a small section of the neck near the case mouth into the bullet . While the collet neck sizing die pinches the whole length of the neck down around a sized mandrel . Similar but not the same.

I wonder if it’s the nut behind the wheel . I’m going to adjust that neck die. To see if I’m pinching it too much.

[tangolima]

Unintended consequence indeed. It should be ok if you keep using only collet die with mandrel. But combination of collet and bushing dies could be problematic.

I would chuck those and start over with other brass. My usual procedure is as follows.

1. Full length size with expander removed, either regular or bushing die.

2. Expand neck with floating expander pushing into the neck. This leaves the best ID concentricity I can possibly achieve. All irregularities are now pushed to OD.

3. Neck turn to have neck wall thickness matching the bushing I have. I tend to keep thicker wall thickness of 0.015" for calibers .243 and above. 0.002" for bullet hold. For .22 caliber, I have to settle for thickness of 0.011" as the brass neck is thin to begin with.

4. From this point on, all full length sizing with bushing die minus expander. I will run the brass through bushing die (no expander) one more time after turning. Trim. Anneal if I feel necessary.

-TL

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[Metal god]

So I went ahead and seated a bullet into that atrocious case . Anyone wanna guess what the concentricity was on the bullet ?
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.001 lol , the case neck may look like crap, but it sure was concentric

This leaves the best ID concentricity I can possibly achieve.

And you measured that how ? I’d love to be able to check the concentricity of the inside of my neck, but I haven’t been able to come up with a way to do so.