Never encountered this before. Springback?

[MrBottleneck]

First I must preface I feel I am a decent reloader but, nowhere near having it mastered as I am always learning new tricks and tips etc.
So, my 6.5cm Lapua is going on third firing so, I figured wth I would use the benchsource and anneal them before this loading.
Prepped 50 cases a couple weeks back with a Redding FL type S with a .290 bushing. Shot 25 rounds of that batch last weekend with fantastic results.
So, I went to throw powder in another 15 I had out of that 25 remaining cases and I had one case that just didnt want to NS.
I even dumped the powder and retried the .290 but, not enough tension.
I ended up just rather then wasting it drop down to a .289 bushing which gave me the same tension as all the prior cases that where done with a .290. Springback I understand but, just one very different from the others? Extra fouler

 

[Mark M.]

After three firings it sounds like it's starting to get work hardened

 

[Homerange]

As cases work harden and if you don't anneal each firing it's a good idea to increase sizing dwell time to minimize spring back.

 

[Webster]

First I must preface I feel I am a decent reloader but, nowhere near having it mastered as I am always learning new tricks and tips etc.
So, my 6.5cm Lapua is going on third firing so, I figured wth I would use the benchsource and anneal them before this loading.
Prepped 50 cases a couple weeks back with a Redding FL type S with a .290 bushing. Shot 25 rounds of that batch last weekend with fantastic results.
So, I went to throw powder in another 15 I had out of that 25 remaining cases and I had one case that just didnt want to NS.
I even dumped the powder and retried the .290 but, not enough tension.
I ended up just rather then wasting it drop down to a .289 bushing which gave me the same tension as all the prior cases that where done with a .290. Springback I understand but, just one very different from the others? Extra fouler

My understanding of what you did:
Annealed 15 cases
sized with a .290" bushing
One case measured 0.001" different in neck o.d. diameter

Things I would check:
Are the necks turned? Are they the same thickness? What's the neck thickness variation as purchased?
If you get another case that's under shoot it at the fouler target and see if it has the same POI.
Make it a fouler
Throw it away.

Exactly what do you mean by one case wouldn't neck size? Did a .290" bushing slip over the neck by hand or are you going by o.d. after sizing?

Anneal a shorter time. You may not anneal as much but you may have less variation in change. Are the necks getting any hint of red in a dark room when annealing? Flame location?

We make an assumption that when we buy new quality cases they are all identical.

Measuring tension with a micrometer doesn't actually measure tension. It's a diameter measurement. It's an assumption that if every case is done the same way the tension is the same. It's the best we can do and should be OK. The method doesn't consider actual variation in case hardness, elasticity ect. Guys on this website have seating pressure gauges. It would be interesting to hear from them. Articles I have read say that sometimes they see big differences in seating pressure and what they did to correct it.

 

[retired]

sounds like your annealing is not as consistent as it needs to be.
one more vote for the AMP

 

[MrBottleneck]

My understanding of what you did:
Annealed 15 cases
sized with a .290" bushing
One case measured 0.001" different in neck o.d. diameter

Things I would check:
Are the necks turned? Are they the same thickness? What's the neck thickness variation as purchased?
If you get another case that's under shoot it at the fouler target and see if it has the same POI.
Make it a fouler
Throw it away.

Exactly what do you mean by one case wouldn't neck size? Did a .290" bushing slip over the neck by hand or are you going by o.d. after sizing?

Anneal a shorter time. You may not anneal as much but you may have less variation in change. Are the necks getting any hint of red in a dark room when annealing? Flame location?

We make an assumption that when we buy new quality cases they are all identical.

Measuring tension with a micrometer doesn't actually measure tension. It's a diameter measurement. It's an assumption that if every case is done the same way the tension is the same. It's the best we can do and should be OK. The method doesn't consider actual variation in case hardness, elasticity ect. Guys on this website have seating pressure gauges. It would be interesting to hear from them. Articles I have read say that sometimes they see big differences in seating pressure and what they did to correct it.

Webster, --No annealed all 50 cases after the 2nd firing getting ready all for this 3rd firing.
I then FL sized all 50 after annealing using the .290 bushing, trimmed, deburred and etc. I hadnt thrown powder into them at that time.
I threw powder into 25 of them last week and seated my 140gr RDFs .005 off and they all shot fantastic.
So, this weekend I have alot to do but, figured I would shot 15 more so, I threw powder into those 15. Its just the one case that would not give me the figured .001 case to bullet tension as the others. No I am not turning necks although I can as have a K&M setup. Just figured its my factory no turn 6.5cm with good quality Lapua SR primer brass why bother.
As far as flame is dual heads about .5" away from blue tip. Checked with Tempilaq high and low on case. No red just typical color (slight) change about 1/8-1/4 below neck.
When I say it wouldnt neck size I should have been more clearer in saying that one case would not give me my .001 tension or so without dropping bushing size too .289

Retired, --Yes an AMP would be nice but, I am satisfied with the BS not to mention my budget wont stretch that far for a $1000. AMP
I seriously dont think that one case out of the group somehow didnt anneal the same as nothing was changed once I got it all set up. I guess anything is possible though.

Mark, -- I annealed the 50 after the second firing then FL sized. This is going to be the 3rd firing.

Homerange, -- If your saying leave in die longer (I assume) I will set that case aside and see what it does this next resizing then possibly ditch it.

Thanks, guys I appreciate the input and will dwelve into some more thorough measurements and will chuck that case probably after this firing after I see how it responds to neck FL sizing.

 

[Dusty Stevens]

Ditch it or keep it for a fouler as long as you can really keep it seperate. Id chunk it just so theres no chance of using it

 

[rardoin]

Ditch it or keep it for a fouler as long as you can really keep it seperate. Id chunk it just so theres no chance of using it

Same here. I find some cases that just won't play well with others. This occurs whether neck turned or not, and fired multiple times, annealed every firing (with an AMP unit). I discard those cases. I hate dropping a point with a shot that has perfect windage but hit high/low.

 

[Bart B.]

Measuring tension with a micrometer doesn't actually measure tension. It's a diameter measurement.

Yes, and it's correctly called an interference fit. It's actually the diameter difference between sized case mouth (inside neck) diameter and bullet.

This is one of several terms and convention issues in ammo speak.

 

[Bart B.]

I hate dropping a point with a shot that has perfect windage but hit high/low.

What if that vertical dispersed shot was caused by a velocity change or an out of square case head?

 

[rardoin]

What if that vertical dispersed shot was caused by a velocity change or an out of square case head?

That is why I eliminate cases that don't size like the vast majority of others...they are more likely to have issues like you query about. Brass is the cheapest part of competitive shooting.