Help - Neck sizing sucks! - now with PICS

[glock24]

I'm hoping for some insight on my situation involving my 6.5x47 Lapua and some really nasty 100 meter groups.

Long story short, I used the round-robin technique to build a very accurate load with virgin Lapua brass, CCI primers, H4350, and 142 SMKs. The only brass prep I did was a very light neck-turn (50%) and a final neck sizing with my Redding bushing die. 41.8 grains of H4350 produces 5-shot groups that are a consistently in the 0.3s and 0.4s @ 100 meters. If my camera was running, I'd post a half dozen examples of this.

Today I went to the range to confirm my bullet drops at longer distances, but discovered my 100 meters groups looked like garbage. I was averaging around 1 inch!

The only difference between then and now is the fact that my Lapua brass is now once-fired. The recipe and components are exactly the same. The brass was simply cleaned, and neck-sized with the same bushing used the first time around.

So it seems obvious I have disrupted my tuned load, and the only factor that stands out to me is shoulder position. I did note that my these once-fired rounds were just bit harder to chamber.

What does this mean? Should I go back and bump the shoulders on my once-fired brass back to the same place as my virgin brass? Or does this mean that I need to conduct a new load development on this once-fired brass?

I'm really frustrated to find the shoulder position changes things so dramatically. I've always read that neck-sized, once-fired brass is better because it is fitted to the chamber. Is my experience normal? Am I missing anything else?

I'm really considering dumping the neck-sizing only philosophy and going with a full-length sizing strategy.

Any opinions would be appreciated.

Thanks

 

[The Mechanic]

Re: Help! - Neck sizing sucks!

Bump the shoulder back to the same as your virgin and see if it returns, and try to maybe anneal the necks on some and try that to.

 

[TimK]

Re: Help! - Neck sizing sucks!

Did you save any examples of the first loading that you could measure? Did you chrono both loads?

I had an extremely similar problem, in my case most of it turned out to be a wind issue. I'm still chasing the last 1/4 moa.

This kind of thing stinks, and I feel your pain. If it's not a hassle, I'd load up 5 FL sized and 5 with the shoulder bumped back if you have a shoulder die. Chrono and shoot for group.

Are you dead certain it's not the gun/shooter/conditions? Can you post pics of the poor groups? Did POI change?

 

[glock24]

Re: Help! - Neck sizing sucks!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tim K</div><div class="ubbcode-body">Did you save any examples of the first loading that you could measure? Did you chrono both loads?

I had an extremely similar problem, in my case most of it turned out to be a wind issue. I'm still chasing the last 1/4 moa.

This kind of thing stinks, and I feel your pain. If it's not a hassle, I'd load up 5 FL sized and 5 with the shoulder bumped back if you have a shoulder die. Chrono and shoot for group.

Are you dead certain it's not the gun/shooter/conditions? Can you post pics of the poor groups? Did POI change? </div></div>

LOL!

I just read your post. It sure sounds like my problem!

I do have more of my original loads (thank goodness!), so I guess I'll have to chrono both of them. Based on the group size differences however, I'm pretty much certain I'll see velocity differences. That doesn't necessarily help me. The big question for me is, "can shoulder position changes cause this?"

My POI did shift slightly.

As for the shooter/conditions, after shooting my ugly 1" group, I immediately grabbed my box of virgin brass loads and proceeded to fire a 0.4" group right next to the ugly one.

I know pictures would help greatly. Let me work on my camera and get something posted.

Thanks

 

[Victor N TN]

Re: Help! - Neck sizing sucks!

Did you neck size with the bushing before or after you turned the case necks?

 

[TimK]

Re: Help! - Neck sizing sucks!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: glock24</div><div class="ubbcode-body"> The big question for me is, "can shoulder position changes cause this?"
</div></div>

Good golly, I hope not. If it does, then maybe it's a case capacity issue? Maybe fire forming the cases increased the volume, changing the pressure and thus the velocity to some new value you barrel doesn't like. That would stink.

Post up that new data when you get it.

 

[gunman_7]

Re: Help! - Neck sizing sucks!

Sounds like case capacity changed, do more load work up with once fired brass, go up in 2 tenths (0.2) of a grain increments until you find that sweet spot again, my guess it will take about .8 more powder to get there. Then just remember that on FL sized brass you have to use less powder... But defiantly use a crono and compare numbers. Your load may just be a very sensitive load to fluctuations...

 

[glock24]

Re: Help! - Neck sizing sucks!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Victor N TN</div><div class="ubbcode-body">Did you neck size with the bushing before or after you turned the case necks? </div></div>

LOL!

I neck-sized (0.287" bushing) them after neck-turning. Before turning, the necks just received an expander mandrel so they'd fit on my neck-turner.

I just measured something strange however;


<span style="text-decoration: underline"><span style="font-weight: bold">Neck-sized virgin brass</span></span>

Sized neck - <span style="color: #3333FF">0.2870" OD</span>
Loaded neck - 0.2895" OD
Difference - 0.0025"

<span style="text-decoration: underline">
<span style="font-weight: bold">Neck-sized 1x brass</span></span>

Sized neck - <span style="color: #CC0000">0.2855" OD</span>
Loaded neck - 0.2890" OD
Difference - 0.0035"

How the hell did that happen? How does the same bushing size the neck differently the second time? My only guess is that the bushing had to reduce the neck diameter further on the fired brass than the virgin brass. Maybe the extra friction caused the change? Or does it mean my bushing was full of brass residue, allowing it to under-size the necks?

So from these measurements, can I now assume this means my 1x brass has more neck tension than my virgin brass? Would another 0.001" of tension cause this much variation in group size?

Thanks for your interest in my dilemma gentlemen. I appreciate the feedback.

 

[TimK]

Re: Help! - Neck sizing sucks!

That's the area I'm looking at for my own problem. Also, my neck die undersizes my brass by at least 0.001" from the stated size on once fired brass. I never neck sized the virgin brass, so I can't comment on any changes.

I don't know if 0.001" increase in tension could change your group size, but I can say for certain that in my own case, neck sizing changed the POI by a full MOA. Amazing and aggravating.

Maybe it's a combination of the two issues, tension and case capacity. I'd take the other poster's advice and fool with charge weight a bit to find the sweet spot again.

If it's true that fired brass shoots differently than virgin brass for at least the two of us, we have an issue with an added step to the loading process, namely firing once. Talk about hassle factor.

 

[Fuzzball]

Re: Help! - Neck sizing sucks!

"I've always read that neck-sized, once-fired brass is better because it is fitted to the chamber."

So, another common web legend dies on its feet.

 

[The Mechanic]

Re: Help! - Neck sizing sucks!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: glock24</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Victor N TN</div><div class="ubbcode-body">Did you neck size with the bushing before or after you turned the case necks? </div></div>

LOL!

I neck-sized (0.287" bushing) them after neck-turning. Before turning, the necks just received an expander mandrel so they'd fit on my neck-turner.

I just measured something strange however;


<span style="text-decoration: underline"><span style="font-weight: bold">Neck-sized virgin brass</span></span>

Sized neck - <span style="color: #3333FF">0.2870" OD</span>
Loaded neck - 0.2895" OD
Difference - 0.0025"

<span style="text-decoration: underline">
<span style="font-weight: bold">Neck-sized 1x brass</span></span>

Sized neck - <span style="color: #CC0000">0.2855" OD</span>
Loaded neck - 0.2890" OD
Difference - 0.0035"

How the hell did that happen? How does the same bushing size the neck differently the second time? My only guess is that the bushing had to reduce the neck diameter further on the fired brass than the virgin brass. Maybe the extra friction caused the change? Or does it mean my bushing was full of brass residue, allowing it to under-size the necks?

So from these measurements, can I now assume this means my 1x brass has more neck tension than my virgin brass? Would another 0.001" of tension cause this much variation in group size?

Thanks for your interest in my dilemma gentlemen. I appreciate the feedback.
</div></div>
Time to anneal..

 

[Kevmo8]

Re: Help! - Neck sizing sucks!

I could be wrong, but why are you neck sizing virgin brass? You should neck size it if it's already been fired in your rifle. I would full length size virgin brass.

 

[former naval person]

Re: Help! - Neck sizing sucks!

You got some brass flow from the first firing. If your neck turning tool is still set up, try turning a neck of the once fired case...measure the thickness of a virgin case neck v/s the fired and sized case. That can get you more neck tension. The difference between fired and unfired sized necks is probably due to work hardening from the sizing and firing, plus the difference in case neck wall thickness increasing. The bushing hasn't changed but the "spring back" from the sizing process has. JMHO

 

[glock24]

Re: Help! - Neck sizing sucks!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: The Mechanic</div><div class="ubbcode-body">
Time to anneal.. </div></div>

Why? Do you think it has been over-worked already?

 

[badbot]

Re: Help! - Neck sizing sucks!

1 less springback with thinner neck?
2 less hold with thinner neck?
3 fireformed brass HAS different capsity.

I think a ladder for virgin, turned and same sized, turned and sized smaller might be called for.

a chrono should be used to find the original FPS.
running the ladder should find the size of the node.
neck tension would be covered also if you run all 3 ladders.
after re-finding the node explore seating depth.

we need a neck tension guage.

another thread had loads with all componets matching but the first half of the batch was seated weeks before the last half.
somehow age after assembly affected tension.

makes me want to buy ammo by the ton just to know what I have. ;-P

 

[The Mechanic]

Re: Help! - Neck sizing sucks!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BadBot</div><div class="ubbcode-body">1 less springback with thinner neck?
2 less hold with thinner neck?
3 fireformed brass HAS different capsity.

<span style="font-weight: bold"><span style="color: #FF0000">we need a neck tension guage.</span></span>

makes me want to buy ammo by the ton just to know what I have. ;-P</div></div>
Ask and ye shall receive.
http://www.shootingsoftware.com/recoil.htm

 

[glock24]

Re: Help! - Neck sizing sucks!

Below are a couple, 5-shot, 100 meter groups with my recipe and virgin brass. This is what I expect from this rifle.

Below are two, 5-shot groups at 100 meters from today's disappointing range session. The group on the left was fired immediately after the crappy group on the right.

It sounds to me like I'm stuck redoing my experiments with this 1x brass. I have a shoulder bump gauge inbound from Sinclair. I'm going to bump the shoulders back to something close to the original, and then try again.

Lessons learned - be aware of internal volume changes and neck tension changes when going from new, to fire-formed brass.

I don't know what to do about my neck walls changing, other than measuring and adjusting tension to suit.

I'm really disappointed though. I didn't have this problem with my 7mmRM. Maybe my accuracy node was larger with my 7mmRM than with my 6.5 Lapua.

Oh well . . .

 

[427Cobra]

Re: Help! - Neck sizing sucks!

Up the charge in .1-.2 increments, the bug hole will return.

 

[ChadTRG42]

Re: Help - Neck sizing sucks! - now with PICS

Some replies are in red
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: glock24</div><div class="ubbcode-body">I'm hoping for some insight on my situation involving my 6.5x47 Lapua and some really nasty 100 meter groups.

Long story short, I used the round-robin technique to build a very accurate load with virgin Lapua brass, CCI primers, H4350, and 142 SMKs. The only brass prep I did was a very light neck-turn (50%) <span style="color: #FF0000"> Why neck turn good brass?</span> and a final neck sizing with my Redding bushing die. 41.8 grains of H4350 produces 5-shot groups that are a consistently in the 0.3s and 0.4s @ 100 meters. If my camera was running, I'd post a half dozen examples of this.

Today I went to the range to confirm my bullet drops at longer distances, but discovered my 100 meters groups looked like garbage. I was averaging around 1 inch!

The only difference between then and now is the fact that my Lapua brass is now once-fired. The recipe and components are exactly the same. The brass was simply cleaned, and neck-sized with the same bushing used the first time around.

So it seems obvious I have disrupted my tuned load, and the only factor that stands out to me is shoulder position. I did note that my these once-fired rounds were just bit harder to chamber.

What does this mean? Should I go back and bump the shoulders on my once-fired brass back to the same place as my virgin brass? <span style="color: #FF0000"> Yes</span> Or does this mean that I need to conduct a new load development on this once-fired brass? <span style="color: #FF0000">Yes, if you plan to run neck sized brass </span>

I'm really frustrated to find the shoulder position changes things so dramatically.<span style="color: #FF0000"> Yes, it changes it up</span> I've always read that neck-sized, once-fired brass is better because it is fitted to the chamber.<span style="color: #FF0000"> Not always true</span> Is my experience normal? Am I missing anything else?

I'm really considering dumping the neck-sizing only philosophy and going with a full-length sizing strategy.<span style="color: #FF0000"> I would do this</span>

Any opinions would be appreciated.

Thanks </div></div>
If you try a few tenths up or down from your original load, you will find the same sweet spot again. I honestly wouldn't mess with neck turning your brass. Too much head ache and troubles are found.

 

[Niles Coyote]

Re: Help - Neck sizing sucks! - now with PICS

If you do a h2o volume/weight test on the new brass neck sized and the once fired neck sized brass you will find the answer to your question.

The factory can get real close to making brass to fit your chamber, but firing the cartridge in your chamber is the final process. The once fired case now has a different/larger internal volume no matter how you size it. Adjusting your load will bring back the accuracy.

At any rate, you have the best load for new brass for your rifle, write that data down and don’t lose it. The next step is finding the best load for fired brass. Take notes on both loads and you’re done. After that you will be golden until you change something in the recipe.

 

[TimK]

Re: Help - Neck sizing sucks! - now with PICS

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Niles Coyote</div><div class="ubbcode-body">
The factory can get real close to making brass to fit your chamber, but firing the cartridge in your chamber is the final process. The once fired case now has a different/larger internal volume no matter how you size it. Adjusting your load will bring back the accuracy.

At any rate, you have the best load for new brass for your rifle, write that data down and don’t lose it. The next step is finding the best load for fired brass. Take notes on both loads and you’re done. After that you will be golden until you change something in the recipe.
</div></div>

I think this is right on. If my similar situation persists after I shoot my once fired brass loads again (hopefully today) I will play with charge weight again to find the node.

I'd continue to neck size to extend brass life. Knowing your load may be sensitive to case volume, I'd consider bumping the shoulder every time. Once you get your gage, maybe you could determine the absolute minimum of bump to get reliable chambering and just do that every time. If you don't and only bump when they get too long, you'll have case volume variations again. I say pick a process for fired brass, whatever it is, and stick to it. Having two recipes, one for virgin and one for fired, isn't horrible.

I hope the guys are correct that the accuracy node of the new load is close by in terms of charge weight. I'd like to know for sure if we should be looking more towards heavier or lighter charges, and how far away from the original load we should have to go. If we can expect to find it again within 1/2grain up or down, that's not too daunting a process to load up in 0.1 or 0.2 grain increments.

Best of luck.

 

[cinosbus]

Re: Help - Neck sizing sucks! - now with PICS

I'm not sure what the problem is, but it might be worth looking at everything else you did when you loaded both batches. It could be something as simple as not re-zeroing your powder scale for one of the batches or re-zeroing it with something touching/binding the scale. Pull a bullet from each batch and check your powder weight.

You also should check concentricity of both loads. You could have something out of whack on your press or dies. Just roll the cartridges across a very flat surface and see if you see runout. OAL the same? COAL the same? Bullets from the same batch?

I have also seen a distinct amount of group variation from new vs once fired brass. The once fired was better in my .308, worse in my .223. Haven't played much with the .223 to figure it out, but I *think* it has to do with shoulder position. Shoulder position definitely matters - but I'm not sure if it's chamber fit and/or case capacity that is the cause. I get more <span style="font-weight: bold">consistency</span> from a looser chamber fit than from a tighter chamber fit in my .308, YMMV.

 

[Jedi]

Re: Help - Neck sizing sucks! - now with PICS

LMAO
Aload is never complete when using virgin brass

firing will increase case H20 capacity therefore ya need alil more powder

Or you could adjust seating depth

lastly load testing @ 100 is pointless, almost any load will shoot@ 100
200 or 300 is better for showing load deviations

After fire forming brass to chamber for that custom fit why would you FL size brass??? this puts you back at square one

fire form then neck size only, if needed use body die to bump shoulder
Thou normally Cammin of bolt will do same thing, i have yet to bump shoulder on any of my brass

Now if you have no turn chamber why oh why did you neck size?
lapua brass i have always run as outta box
But i dont run tight neck chambered guns either

 

[Ares]

Re: Help! - Neck sizing sucks!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: glock24</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Victor N TN</div><div class="ubbcode-body">Did you neck size with the bushing before or after you turned the case necks? </div></div>

LOL!

I neck-sized (0.287" bushing) them after neck-turning. Before turning, the necks just received an expander mandrel so they'd fit on my neck-turner.

I just measured something strange however;


<span style="text-decoration: underline"><span style="font-weight: bold">Neck-sized virgin brass</span></span>

Sized neck - <span style="color: #3333FF">0.2870" OD</span>
Loaded neck - 0.2895" OD
Difference - 0.0025"

<span style="text-decoration: underline">
<span style="font-weight: bold">Neck-sized 1x brass</span></span>

Sized neck - <span style="color: #CC0000">0.2855" OD</span>
Loaded neck - 0.2890" OD
Difference - 0.0035"

How the hell did that happen? How does the same bushing size the neck differently the second time? My only guess is that the bushing had to reduce the neck diameter further on the fired brass than the virgin brass. Maybe the extra friction caused the change? Or does it mean my bushing was full of brass residue, allowing it to under-size the necks?

So from these measurements, can I now assume this means my 1x brass has more neck tension than my virgin brass? Would another 0.001" of tension cause this much variation in group size?

Thanks for your interest in my dilemma gentlemen. I appreciate the feedback.
</div></div>
My question is:
What was your virgin and once shot brass neck OD <span style="color: #CC0000"><span style="font-weight: bold">BEFORE</span></span> neck sizing?

 

[badbot]

Re: Help! - Neck sizing sucks!

I got out my unfired lapua and compaired it to once fired.
the fireformed holds 1.8 gr more VARGET than the virgin brass.
I think thats enough to cause you to slip out of the node.

--------
to the machanic, OK i'll ask, could you send me one of those?
i'd like to test it for 6-8 years and then return it. I could also use a presure-trace and dopler radar to gather some data on my loads.

 

[The Mechanic]

Re: Help! - Neck sizing sucks!

You may have to give me a little while on that Dopler radar.

 

[Alan Griffith]

Re: Help! - Neck sizing sucks!

What's your chamber specs say your neck Dia is?

What's your fired case neck size?

Why are you turning your necks 50%? What about trying to shoot your loads with original, un-turned necks?

My best accuracy with my .294" necks is when I use the .289" bushing. I tried both .287" and .288".

Alan

 

[former naval person]

Re: Help! - Neck sizing sucks!

Have you considered doing a "ladder" test as described in the "Powdering it" sticky? Perhaps that would help you find a less sensitive node instead of such a sensitive load. JMHO

 

[Lumpy Grits]

Re: Help! - Neck sizing sucks!

What is the TIR on run-out with your first load rounds and what is it with the second loading when you neck size?
FWIW: I f/l size ALL my long range "junk" cause I can keep the TIR to .002" or less.
Respectfully,
LG

 

[TimK]

Re: Help! - Neck sizing sucks!

Bad Bot,

What's your plan?

I shot my similarly performing load again yesterday and found my problem was not only wind. I've loaded up 7 new loads starting from 0.2g under the original charge and going up to 1.0g over the original in 0.2g increments. I also FL sized some cases and loaded them with the original charge. The wind is blowing 40 mph here until Thursday, so I won't get to test until then at the earliest.

Have you decided what to try yet?

 

[TimK]

Re: Help! - Neck sizing sucks!

I found I had to increase the charge 0.8g to get the same performance in once fired, neck sized brass that I got with FL sized virgin brass.

Surprisingly, FL sized once fired brass did not shoot the same as FL sized virgin brass. That one has me baffled, but since I don't plan to FL size I'm not going to worry about it.

 

[glock24]

Re: Help! - Neck sizing sucks!

I hit the range yesterday, and ran another round-robin with my neck-sized brass.

Like Tim K, I also needed 0.8g more H4350 to get the same performance as my virgin brass load.

Live and learn.

Thanks for the insight gentlemen.

 

[MitchAlsup]

Re: Help! - Neck sizing sucks!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: glock24</div><div class="ubbcode-body"><span style="text-decoration: underline"><span style="font-weight: bold">Neck-sized virgin brass</span></span>

Sized neck - <span style="color: #3333FF">0.2870" OD</span>
Loaded neck - 0.2895" OD
Difference - 0.0025"

<span style="text-decoration: underline">
<span style="font-weight: bold">Neck-sized 1x brass</span></span>

Sized neck - <span style="color: #CC0000">0.2855" OD</span>
Loaded neck - 0.2890" OD
Difference - 0.0035"

How the hell did that happen? </div></div>

What was the obturated neck diameter?

My guess is that you sized the neck in a single step. This, also, overworks the brass in the enck. So, if the obturated neck diameter is more than 0.006 larger than the final sized diameter, you need a second bushing and size the neck in two smaller steps. One big step is known to oversize by 0.001--which is just about how far oversized your neck is, now.

 

[glock24]

Re: Help! - Neck sizing sucks!

Interesting. I didn't know that. And yes, I was neck-sizing in a single step.

The neck O.D. from one of my a fired cases is 0.293" (.295" chamber). It looks like I'd benefit from a two-step neck-sizing process.

Thanks