Neck Tension the Extreme Spread Culprit

[CJS-6.5]

Just for kicks I loaded up 50 140 eldm in virgin Hornady brass. I did zero case prep. Just eyeballs them for major flaws, lubed and loaded. I ran 20 through my chrono doing ladder tests of 5 shots per weight. I stopped because my extreme spread was as high as 147 fps. I figured my scale had pooched so I went home and started pulling bullets and weighing powder charges on two different scales. The first thing I noticed while pulling bullets using the collet pulled in my press was the huge variance in effort needed to pull bullets. Some would fall out and some were scary tight. And all the powder weights were within .1 grn. So I figured my die was loose. Nope fine. Then I started weighing and measuring my brass...holy cow who made this stuff? Now I see why the pros separate their brass into lots...

Just an observation for those who might be struggling with non consistent velocities.

 

[Brux]

So I am taking it that you did not run your brass through a die before you loaded it?
What kind of brass are you using and what kind if difference in weight are you getting?

 

[magoo22]

I found the same thing with new brass with the exception of Nosler. I have 800 Lapua .308 brass and they all were inconsistent until the second shot. I neck sized and carefully checked the rest of the dimensions and found that my SD and Extreme spread were less than 1/3 of the first shot with the same load. Nosler was about 1/2 less on the second shot but also improved. I've run new brass through all the possible forming and still find the second shot is the best with a neck size only. 3rd time is still good but now I'm looking at trimming and annealing to keep things consistent.

 

[Milo 2.5]

Just for kicks I loaded up 50 140 eldm in virgin Hornady brass. I did zero case prep. Just eyeballs them for major flaws, lubed and loaded. I ran 20 through my chrono doing ladder tests of 5 shots per weight. I stopped because my extreme spread was as high as 147 fps. I figured my scale had pooched so I went home and started pulling bullets and weighing powder charges on two different scales. The first thing I noticed while pulling bullets using the collet pulled in my press was the huge variance in effort needed to pull bullets. Some would fall out and some were scary tight. And all the powder weights were within .1 grn. So I figured my die was loose. Nope fine. Then I started weighing and measuring my brass...holy cow who made this stuff? Now I see why the pros separate their brass into lots...

Just an observation for those who might be struggling with non consistent velocities.

You really should have been able to feel that when you seated them the first go. I'm assuming 6.5 creed here, usually hornady new has ungodly tension. I'm not a fan of running new brass through a die, but will expand with carbide expander die, then either anneal again or not, then re-tension with a bushing neck die.
Some new brass, like Lapua 6.5x47, he first firing may be the best of it's life, before we can mess it up.

 

[TimK]

I anneal every cycle for exactly this reason. If I don't, I see variations in seating effort.

 

[TimK]

Crimps are typically bad for accuracy. You've likely got varying hardnesses in your necks and that's causing the variations in neck tension and seating force. All bad. Annealing is the only way to fix it.

 

[waveslayer]

Don't crimp, unless you have a gas gun. Even then I never crimp

My wife thinks I only have 3 guns

 

[Mtleadfarmer]

I full length size all new brass, anneal every time and use a Lee FCD on everything. I've never seen a Lee FCD hurt accuracy.

 

[300ATT]

I started to play with a Lee collet neck sizing die. This die de-caps and forms the neck around a mandrel thus uniforming neck thickness as well as tension. So far the results seem to indicate that this is a good way to go:

run brass through a body die to FL resize, clean then run through the Lee collet neck sizing die. One extra step but I don't have to worry about media in primer holes or turning necks. YMMV

 

[padom]

It's been beaten to death but you shouldn't pay any attention to spreads or do load development with virgin brass. Fireform it in your chamber than neck or FL size and then start your testing.

I do run virgin brass through a expander mandrel to open up the cases with too much neck tension but tension is all over the place with virgin brass including lapua.

 

[wapiti16b]

What the Fly Fisherman said !

 

[Horns8491]

I vote that we all wait to reply to any post w questions until padom responds. Hes gonna provide the correct answer anyway and it’ll save everyone a bunch of trouble.

 

[Deleted member 10043]

Strange how match grade factory ammo...

 

[arnie19]

If this is 6.5 Creedmoor Hornady brass ,I weighed 100 cases and found a spread of 8+ grains .Lapua , only 1.8 grains .I have also found the necks vary enough to see why your neck tension was all over the place .

 

[Supersubes]

This is how bad information starts about certain loading practices. The OP’s necks weren’t treated to make them a consistent size, like they would have been upon his second loading, leading to an improper conclusion that the virgin case was at fault. I mostly shoot peterson and lapua brass. I run them over a mandrel or FL size (depending on their headspace dimension), inside chamfer, the load them. No sorting of anything else. In my opinion, the case is never in better shape than when it’s virgin. FL sizing a fired case gets you right back to where the virgin case was with regard to chamber clearance around the case. Obviously this can be combo specific as chambers and FL dies can vary a lot, but it isn’t a drastic difference. I fully expect single digit sd’s and good accuracy from my virgin 6.5 CM loads.