Criteria for segregating cases

[s mac]

I'm thinking of segregating cases by weight, I've got several .223 Rem once fired, and wondered how much variation per lot. 1 grain, half grain, less or more? These are all 1 headstamp.

[Love Life]

Depends on what your intended use is to be honest. For just "Plinking" I wouldn't bother. For ground squirrels, bunnies, and stuff I might bother and then it might be within... actually I don't bother.

For target work, it gets exhaustive, but within .5 to .3 gr will suffice most the time. Then when you shoot, sort out the uncalled fliers. Then sort by "feel" when seating. You can get as mild or wild as you want with it.

Now the real question: Will your rifle show an improvement for the amount of effort it takes to weight sort your brass?

[s mac]

I haven't even started loading for this yet, a new to me Contender, so I don't have a baseline. This batch of brass is to be split with a friend and I thought it would be beneficial to both of us to be as uniform as possible.

[Love Life]

If you want to segregate, then by all means it definitely won't hurt anything. Sort it in 1 gr increments and see how many "batches" you get out of that lot of brass. Then go from there.

[Petrol & Powder]

When seeking the maximum accuracy out of my loads, I've sorted .308 brass by weight. I would weigh the cases on a digital scale and place them on a scrap of paper with the weight denoted. You'll end up with several batches and then you have to decide how many batches you want to combine in order to obtain sufficient numbers in each group. It is a tedious process that I only perform when trying to squeeze out that smallest group size. I perform all of the case prep first (cleaning, trimming, squaring & cleaning the primer pocket, deburring the flash hole). Good luck and be careful that you don't lose your sanity. :shock:

[Artful]

assuming normal distribution
http://blog.lib.umn.edu/copyrightlibn/normal67.gif

[s mac]

Thanks for your input guys.

[Love Life]

Get buck wild and order some primer pocket plugs....

[Petrol & Powder]

In my decidedly un-scientific method....I ended up with a distribution of brass in little plies that was remarkably similar to the bell curve posted by Artful!

[Love Life]

The bell curves are much smaller when you start with Lapua or Norma brass. With Winchester brass I usually am able to come up with 100 cases within1 gr of each other after sorting through 250 cases...

[Bigslug]

Many moons ago, somebody did an article about this in Precision Shooting Magazine. They had done some study into how case volume affected chamber pressure, or at least velocities, and cooked up a formula to help you figure out how much of a change in case weight equated to adding or subtracting a tenth of a grain of powder (which is the smallest unit most of us can measure).

I don't recall the formula, but I DO remember that because of it, I split my .308 Highpower competition brass down the middle of it's six grain range, having concluded that if all the brass in a box of ammo was within three grains, differences in volume would be negligible.

Since .223's are smaller, the acceptable spread is going to be smaller as well. Just the difference between a .308 and a .223 alone would have me splitting .223's into 2 grain batches. Unless you're playing the Benchrest game, I wouldn't fritter away my life going tighter than 1.5 grains. . .

. . .EXCEPT FOR LOAD DEVELOPMENT. There, you want you test cases to be as bang-on as possible.

Part of the solution I arrived at was simply going to better brass. It's true Norma and Lapua cost more, but two minutes with it at the scale will demonstrate that you don't have to sort it by weight. Your time is worth money too.

The other half of the solution was changing the loading process, based on a discovery Dad made while reading another Precision Shooting article.

The deal is that you start with 20-30 cases that are as consistent as you can easily get them (weight's a good way to do this).

Then you look at the range of powder charge you plan to be in. You load ONE cartridge with your starting charge and mark it as containing that. Then you load ONE cartridge with 2-3 tenths of a grain more powder (for .223 I'd go 2 tenths) and mark it. And so on up to your maximum charge.

Finally, you fire your rounds in ascending order of powder charge over your chronograph. Then you look at your data for the flat spots in the curve where your powder charge has increased by three to four of your 0.2 grain increments, but your velocity has not substantially changed. What you have found is a place where minor variations in your powder charge, and by extension, your case volume, do not effect the performance of the round. Load right smack in the middle of that flat spot and you'll be safely away from the peaks and valleys where they do. A little laborious up front, but a big time, powder, and bullet saver down the road.

[Artful]

BigSlug is correct their are sweet spots in load development and most often correspond to good group size.
Few of my rifles do their best grouping at top velocity.
take a look at this link.
http://www.6mmbr.com/laddertest.html

[fastfire]

I know some local Benchrest shooters that group their brass by FPS.

[Love Life]

There are a whole lot of ways to skin this cat. Using the ladder method and/or ocw will show you your sweet spots or "nodes" as well.

At the end of it all, I also listen to the targets. If I get uncalled fliers, that piece of brass is segregated and relegated to ground squirrel duty.

You can also sort your loaded rds by neck tension. There are gauges that measure the amount of force required to seat your bullet.

You can spend hours at the bench doing insane brass prep and load development, but you have to ask yourself (A) what is your accuracy goal (B) what is the purpose of the rifle, and (C) will your rifle even show you the differences in your prep? Felix said once that trying to turn a 2 MOA rifle into a 1 1/2 MOA rifle is not worth the added effort. However; turning a 1/2 to 3/4 MOA rifle into a sub 1/2 MOA rifle through insane brass prep and load work IS worth it.

Example: My AR's will never be more than a 2-4 MOA rifle so I just load some FMJ over 'splody powder and call it good. For my long range stuff I put in the extra effort and it shows down range out to 1,000+ yards.

[Artful]

The ultimate bughole group I ever saw shot was with one brass case loaded with a lee loader at the bench - it showed me that consistancy in loading can make a real difference.

[4rdwhln]

I only shoot Remington brass in one of my .223 rifles. every case is weighed and the weight wrote on the side. Then I shoot it in increasing weights till its gone. I figure that way the shots should always behave similar to one and other. I am not a good enough shot to really notice the difference, however a guy I used to shoot with was able to shoot 1 hole groups with my gun and load.

[Artful]

I am not a good enough shot to really notice the difference, however a guy I used to shoot with was able to shoot 1 hole groups with my gun and load.

Don't you just hate that :sad: - And it's worse when you used to be the guy that could do it and now can't.

[Big Boomer]

Years back I settled in on a set practice for a Rem. 788 in .223. Being cheap, I came by some TW-'72 military surplus brass, didn't bother with any weighing or sorting of the brass, but did anneal the necks, trimmed for length and then neck turned the brass just enough to be sure the neck tension was as near uniform as possible. Using some 844 surplus powder and Nosler 52 gr. match bullets, that rifle off sandbags would place 5 rounds into 1/2" with a certain load. Sometimes you can just fall into that proverbial hole and luckily come out smelling like a rose. I'm still using the same brass, bullets and powder in that rifle. Big Boomer