Mixing brass of the same lot number

[Dimner]

All I know of is 220 Russian and 6BR.

When measuring with a Ball Micrometer, both are thinner by about .0005 when going from the earlier cases to the new.

I have three new boxes of Lapua 6BR that I am using in my no neck turn 6BRA, (.272 neck), and the neck wall is very consistent in thickness. Some of the best I have seen. The wall thickness is an average .0124.

Jackie, your post reminds me... something I keep forgetting about. This may help out other amateurs like me.

I really don't have enough confidence in my mic skills to trust anything other than the thousands place. or maybe being able to tell if it's above or below .0005. I have the mic with the clutch, and I use a mic vise. I will spin a piece of brass that I have marked off in quadrants on the neck. Each quadrant labeled A,B,C,D. After rotating 360, when I get back to the same letter, lets say C, it will often be +/-.0001 or even +/-.0002 from the measurement before.

I'm using the Shars tube mic from 21st century. I'm not sure if that is part of the problem, or maybe the clutch? However, I suspect that an experienced fella could do just fine with it or 21st cen wouldn't be selling them.

The bottom line is, until I can afford a very consistent neck turning setup, I continue to lack confidence in my readings. I'm hoping that when I get my neck turning setup, and do some skim turn tests, I will be able to re-measure and possibly get a better idea of what I need to do to get more consistent readings.

 

[Dimner]

I picked up that tip from @BartsBullets , a performance based , results driven exercise that’s easy to do.

would you mind telling us more about that?

Do you do it with specific bullets, is it already fired brass?

 

[RegionRat]

That is the theory that you can sort out "bad" cases by rejecting the ones with velocity (or group) that is out of family, rather than using mechanical inspection of the brass.

Some take the concept to mean velocity is used to cull high or low cases.
Some take the concept to mean target performance, wherein they cull any brass that throws a flyer.

You shoot them in test, and reject the ones that are too high or too low in velocity, or by group, for your taste.

The method costs you a shot to find out, but skips the mechanical inspection of dimensions, weights, or volumes. There are folks who run inspections first anyway, then apply this theory too. YMMV

 

[Doug Casner]

Well, I have trouble with the thinking that one lot is all good because it was in that lot. We had 26 taper machines running the same lot at Lake City and they werent all running the same. If you wanna find the perfect brass you better have a whole set of guages and cull them yourself. Doug

 

[Dimner]

Well, I have trouble with the thinking that one lot is all good because it was in that lot. We had 26 taper machines running the same lot at Lake City and they werent all running the same. If you wanna find the perfect brass you better have a whole set of guages and cull them yourself. Doug

I wish we could poll the top ten benchrest shooters over the past few years. See what they do.

 

[Coyotefurharvester]

Without any information on what constitutes a lot number, the number on the package is just a number.

 

[Doug Casner]

Im willing to learn. I dont wont to sound like a know it all. Maybe its in the loading of that lot. I tried to avoid loading area. Spent about my whole time in the case area. I could see losing a lot because it wasnt loaded right. all the case had to do was chamber. Doug

 

[quest450]

I recently bought two boxes of Lapua brass, both are the same lot number. Can I mix those two boxes of brass together and make it a 200 piece batch without it affecting accuracy at tournaments?

definitely !

that's what I do, I shoot 600 and 1K, I split 500 cases (same lot) into two batches of 250,
enough for some testing and a two day match if I choose to shoot the same gun for LG & HG.
I like to fire my brass 3X before I trust it to shoot it in a match, I turn necks, uniform pp, debur flash holes and trim it before I sort my brass by internal case volume to eliminate any HI-LO outliers, I like carbon build up in the necks for lubrication and I don't clean my brass (outside only)

 

[RegionRat]

Well, I have trouble with the thinking that one lot is all good because it was in that lot. We had 26 taper machines running the same lot at Lake City and they werent all running the same. If you wanna find the perfect brass you better have a whole set of guages and cull them yourself. Doug

That said... you can do a whole lot worse than LC brass.
Before the importation of the better brass, we sorted and prepped LC and did just fine (if you ignored the extra work). Folks that missed that fuss don't know how good they have it now.

 

[Webster]

Well, I have trouble with the thinking that one lot is all good because it was in that lot. We had 26 taper machines running the same lot at Lake City and they werent all running the same. If you wanna find the perfect brass you better have a whole set of guages and cull them yourself. Doug

What contitutes alot? Can the cases be formed on different machines and called the same lot. If one die is changed is it a new lot. Same die 1000 cases or 50,000 same lot? /what dimension goes out of spec when it's time to replace a die.

 

[Bill K]

Lapua or any brass, even from same lot, will vary if you weigh each case. Best, if you want to really try to match cases, is to size, trim, camfer each case, then weigh and sort them into groups for final loading.
Then you should be about as close as you can be to having a match group for shooting.

 

[JFrank]

@barefooter56
Perhaps you could add some clarity to this thread regarding the consistency of brass within the same lot number and just as an overview what this process looks like if one was touring during a shift.
Thanks
Jim

 

[RegionRat]

If one were to know these details, they would not be free to disclose them publicly.

Anyone who sets foot into that world, has signed PIA and NDA contracts that prevent them from publishing details. Violate those contracts and your world is over in more ways than one. YMMV

 

[JFrank]

People are free to speculate or spread conjecture, where I would prefer to simply ask a reputable source with personal knowledge. No one is asking for trade secrets or formula’s or no discloser violations , just some clarity and perhaps an overview.
For example’ are there 10 machines running 24/7 dumping brass into huge bins then automated distribution into 100 count boxes ?

 

[Webster]

That is the theory that you can sort out "bad" cases by rejecting the ones with velocity (or group) that is out of family, rather than using mechanical inspection of the brass.

Some take the concept to mean velocity is used to cull high or low cases.
Some take the concept to mean target performance, wherein they cull any brass that throws a flyer.

You shoot them in test, and reject the ones that are too high or too low in velocity, or by group, for your taste.

The method costs you a shot to find out, but skips the mechanical inspection of dimensions, weights, or volumes. There are folks who run inspections first anyway, then apply this theory too. YMMV

Picture from the Federal website. What part of this is a lot?
They may have 10 or 20 side by side presses extruding the same caliber cases with different dies and dumped into one bin. Each case goes thru a series of at least 5 extrusion dies. 10X5 = 50 variables.

 

[RegionRat]

Picture from the Federal website. What part of this is a lot?
They may have 10 or 20 side by side presses extruding the same caliber cases with different dies and dumped into one bin. Each case goes thru a series of at least 5 extrusion dies. 10X5 = 50 variables.


View attachment 1526014

In the post I made, I was trying to shed light on the question from Dimner on culling or sorting by shooting test rather than inspection.

I have already stated earlier and on several threads, there is no standard definition that defines "lot" or "batch" between different commercial suppliers. They each have their own versions of traceability to lots or batches with some similarities and also with some differences.

My advice is always two fold, take it or leave it.
One is to learn to keep a diary and notes on your loading that includes learning to inspect your components, in this thread the focus was brass. The details should go down to batch level.
Two is, to learn what the tolerance level that triggers you to accept, reject, or sort, and why.

Those are long deep concepts, and each loader/shooter needs to decide for their own purposes how far down the rabbit hole they go with mechanical inspections, learning internal ballistics, and what is important to their style of shooting.

Setting your tolerance is not a beginner's topic, nor is being able to shoot well enough to prove it. You can mitigate that learning curve by using the higher quality components, but even this can only go so far. YMMV

 

[Doug Casner]

Seems like a lot was just a number . A place in production you could go back to if their was a problem. Well this lot is o.k. so pack them. This new lot , we will test more. That was in the dark ages so I dont know what they do now. Doug

 

[JFrank]

Maybe there is some facts at the website https://www.lapua.com/products/cartridge-cases/

 

[gunsandgunsmithing]

And then...the wind started to blow. Yall finish the story for me.

 

[Dimner]

Not exactly what we are talking about.... I'm sure there are very big differences, but I bed the hardcore rimfire shooters could shed some light on some of the basic manufacturing practices Lapua uses. Those guys are seriously dependent on Lot# variations. If I know anything about manufacturing, a company will use a successful QC process in many areas of their product line.

However, yall convinced me that until I'm sitting next to you guys on a line competing, I'm going to take all my same lot # brass put it in a big bowl make sub groups of what ever I need quantity wise. I wont be able to shoot the difference for quite some time.