Newbie head explosion

[6.5x300 WBY]

Ok I am about to explode with this I just don't understand what's going on here.
So here is the line up for equipment I guess you'll be asking about.
6mm creed
Redding turret press with creedmoor sports upgraded head.
Mighty armory match fl sizing die
Brass. My main brass is Alpha but I am playing with factory x1 shot hornady brass because who cares its just hornady brass and if I mess up trying to figure things out no big deal. Want to save my alpha brass for when I got a hold of things.

Ok so with factory x1 fired brass i used my Hornady headspace comparator
1.558. So now I adjust my die walking back the shoulder a little at a time to 1.556. Great lock the ring down and I'm set. SUPPOSEDLY!! grab another case and it's 1.5575 so I fl size it and now 1.5545. ***. So I go back to that previously measured case that I walked back that read 1.556 exactly what I want. Send that through the die and reads 1.556. DOUBLE "***"
I CANT TAKE THIS what the hell is going on here.

 

[PddPdd]

When modifying the headspace on a fired case I find that I will get different results depending on if all the brass is being resized from the chamber/ejected dimension vs. walking it back in step by step increments. So in my experience you should start with a fresh piece of fired brass when setting your die position. Then work on your trial pieces of resized brass after getting the die set.

To get your trial pieces sized correctly I run them through the die several times, rotating the brass a few degrees prior to each stroke. Annealing may help with getting the trial pieces to reach the final dimension you want.

The reason this happens is because you need to deform the brass past the point of plastic/permanent deformation. Brass can take small deformations and just spring back to where it started rather than deforming to the new dimension you are trying to achieve. Hope this helps.

 

[Doom2]

Let me get this straight, you are sizing one piece to 1.556 and another to 1.5545. SO the difference is .0015"? If that's your question it then get over it. There are reasons for this and one is the brass inconsistency in hardness. In some cases its the amount of lube on the shoulder of the cartridge. It can be a result of the amount of lube on the inside of case neck. Since this is a turret press there is probably an adjustable stop on the press opposite the ram side that is adjusted to prevent the plate from tilting during sizing. Check that. Its not reasonable to expect every piece to size exactly to 1.556 because one piece did.

If you can't take this type of variation you are going to explode.

 

[Tagnbagem]

Make sure when you resize that you use the same amount of lube. I use a RCBS lube pad and if it needs more lube than I am applying I get a different bump size and have proven this. So just be aware.

 

[Tagnbagem]

Make sure when you resize that you use the same amount of lube. I use a RCBS lube pad and if it needs more lube than I am applying I get a different bump size and have proven this. So just be aware.

Maybe think about getting the Redding Competition shell holder set.

 

[Koda_]

So now I adjust my die walking back the shoulder a little at a time to 1.556. Great lock the ring down and I'm set. SUPPOSEDLY!! grab another case and it's 1.5575 so I fl size it and now 1.5545. ***. So I go back to that previously measured case that I walked back that read 1.556 exactly what I want. Send that through the die and reads 1.556. DOUBLE "***"
I CANT TAKE THIS what the hell is going on here.

You can "squeeze" that much tolerance with thumb pressure on the calipers alone. Don't beat yourself up here. Slow down and use a light touch on the calipers and be consistent.
If your not annealing you may see larger variations in case measurements after sizing.

 

[Wingnut00]

Maybe think about getting the Redding Competition shell holder set.

I agree. With the comp shell holders I can't measure the difference between cases. They are dead nuts every time

 

[bultinkle]

All of that brass is fine

 

[Dmagna]

Consider it good with hornady brass. It's inconsistent, probably wasn't annealed. It's fine

 

[QuietTexan]

First off, don't sweat any measurements that are within 0.001-0.002" when using Hornady comparators. If Hornady brass sucks like everyone says, why would we expect the tools to be any better? Hint: they aren't.

There's an illusion given by the false precision of the caliper showing out to .0005" that makes it seem like the tool can resolve to that level of detail, but the tools themselves are not that precise. Hornady comparators are usually nonconcentric, on the bad ones as you roll a case in the tool you get a range that will bounce by +/- 0.001" easily. Some more, some less. Unless you get a certified pair, calipers will commonly have a scale error in the range of +/- 0.0020" in the 2-4" measuring range. Stack those issues together, and all the sudden being within 0.002" is fine because that's the reasonable limit of the tools themselves.
That's not getting into tolerance stacking errors on the component side. Brass hardness, thickness variations, concentricity, etc. Set the die using measurements on a few cases, then run the rest and don't bother measuring every single one. Let the target talk and listen to it.

To get better results than the tools can resolve (essentially making them show the same reading because the inputs are inside the error range of the tools) means what you measure has to be better than the tools to resolve. Which is why we match brass, sort it, anneal it, measure it, etc.

Ok so with factory x1 fired brass i used my Hornady headspace comparator

Quit trying to make sense of cases that aren't fully formed yet, it's all a guessing game until you actually let the cases grow to the chamber. Don't even try to bump the shoulder the first time. Put the case back in the rifle, if the bolt closes take it out and set the die size about 3/4 of the neck then shoot it again. You have no idea if you're oversizing cases or not because you don't actually know the length of the chamber in your rifle. With your method you're sizing cases 0.002" under whatever they retracted to after firing, not 0.002" under chamber size. The 0.002" bump rule of thumb comes from sizing a fully formed case enough to be able to extract from a chamber after firing.

Some of my better rifles go 3+ firings before they fill out to the chamber. It comes from not overpressuring the brass when it's new, because new brass sucks in a lot of energy the first time it's shot.

 

[Bob Wright]

I'll add, you'll have to set your dies different once you start using the Alpha brass. Brass chemistry and work hardening over firings, resizing will be different. Hopefully way easier.
You might anneal the Hornady brass first then run them through the dies.
My 7RM brass was varying .003 on headspace, with about 3 firings prior to another run through the FL dies. Once annealed , sized and re-fired, they were almost identical on that headspace measurement. Easy peasy from that point forward.

 

[Doom2]

Lots of good advice and information here. One thing that I will add is you will probably never be able to see any difference in accuracy with a 0.002" setback, +or minus 0.0015".

 

[59FLH]

Every time you adjust the die use a different piece (not previously sized) piece of brass.

As others have said +/- .0015" is is the noise.

 

[6.5x300 WBY]

Thanks guys. To clarify. I am using the brass from a factory load that I bought to shoot in my rifle. obviously hornady brass. It was just weird how much difference there was from 6 to 8 pieces of brass. Most of this factory brass. CBTO grew to 1.558 post firing in my rifle. I was shooting for a bump to 1.556. AFTER FL sizing they ranged from 1.5535 to 1.556. Is that much difference normal??
Now that makes sense about my equipment could be the issue. So would this be an acceptable variants in CBTO?
ANNEALING is in my future. AMP when I can slip that by my wife