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Why does the case matter?

nwslopoke

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I didn't want to go off topic on another thread. But it brought up a question. Why does the shell case matter as far as accuracy?

From my non reloading logic, the case only goes so far into the chamber. I would think only the bullet, powder and barrel would make any difference.

My thinking is brass case and steel case use different type of powders. Steel case ammo uses a lower quality less expensive bullet which leads to less accuracy. How many points did I get?
 
My 2¢
When you want to deal with extreme precision, i.e. guys who put all their shots inside of a nickle at 600 yards, you want to eliminate as many variables as possible. In that instance, you're using cases from the same manufacturer, all withing a specific weight of each other. You'll also use specific primers from the same manufacturer, accurate powder loads from the same manufactured lot, bullets that have the same weight and identical shape (metplat forming, etc). You can get as OCD as you want. There are guys who will cool their barrel between shots with a water soaked towel.

If you just want to put all your shots in the chest area of an AR500 target at 300 yards, then case doesn't matter as long as you know the dope for the bullets you're shooting.

Then again, if you're a consistent MOA or better shooter, and you buy a box of any bullet and it shoots 2-3 MOA, then the case and manufacture does matter - the stuff is crap.
 
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As mentioned, cases can have a fairly large effect depending on your definition of precision and accuracy.

Case necks with uniform thickness all the way around, uniform length, uniform hardness, flash holes deburred, primer pockets uniformed, uniform case capacity, weight sorted after prep, flash holes centered, etc etc etc.

There can be quite a large difference in quality between manufacturers. Getting a load to shoot MOA requires a lot less attention to detail than sub-half MOA.

You can literally go down as many rabbit holes as you want chasing after the elusive dragon.
 
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Consistency in the case makes a huge difference .
The flash hole , if not uniform and consistent from case to case , will not ignite the powder the same from case to case .....equaling inconsistent velocity.
Case wall thickness must be uniform from case to case or it will create inconstancy in case volume , equaling inconsistent velocity.
Neck tension , or neck wall thickness, must be consistent or it will not release the projectile consistent from case to case so if you load a length that jumps to the lands then it will not hit the lands consistent from round to round , if you load into the lands, then tension might effect length as it jams into the lands upon battery
Case consistency for precision shooting is as important as anything in the reloading process
 

AndyinEverson

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Consistency , as noted by the posters above is a key part of accuracy.
A quality well made cartridge case will help keep things in line and consistent.

Consistency is important even when using loose powder , patch and round ball....
With some rifles of mine a little variance in this consistency of loading will make for a big difference in shot placement.

Which brings us to one of the many reasons a self contained metallic cartridge was invented...Consistency...:D
Andy
 
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As noted above, consistency is important / critical. When looking at different materials (brass vs. steel) there is also the expansion that either does or does not occur. That can be one of the issues with steel cases; they do not expand completely like brass so the seal is different (and one of the reasons why they can be dirtier...along with the crappy "glue" they lubricate the case with). Nice thought provoking OP.
 
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Think of a circle inside another circle. Bullet/Case mouth.

If the case mouth is out of round due to to more metal being on one side of the case neck than the other, the bullet will release with with a minor yaw vs one that is a perfect circle inside another circle.

Also where the case shoulder transitions to the neck can get some bulging or build up of brass that will torque your bullets. These are a couple reasons for outside neck turning and inside reaming.

Adjusting your shoulder bump for your type of rifle just keeps your case lasting longer being you are "working it" less. Though i believe if you grossly oversize brass, accuracy will suffer a bit.

Brass does have memory. Firing new brass the first time in the chamber for which you are going to reload for will be optimal. The next time the brass takes a firing it will somewhat remember its "fire-formed" shape.

The more brass gets worked the more it wants to grip the bullet and also spring back after sizing. Annealing makes it soft and malleable again.

Sometimes that big flier you get is due to a bad piece of brass. Some guys when they get one of those just throw that piece of brass away.

Some brass comes from the factory looking like a banana. You would never know it if you did not measure it for concentricity though.

All this stuff is more geared toward long range shooting.

Though it gives you something to think about next time you have 4 shots in one hole and then a flier turns it into a 1 inch group. In general there is about 6 pieces of brass per 100 count bag that need to be tossed out after measuring.
 

AMT

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Have you ever weighed your brass? If the brass is different weight, that means there is either less (or more) material in the shell.

The chamber of your rifle is a specific diameter. So the outer dimension should always be the same. Especially after running it through your sizing dies.

Now, that leaves the internal area of the cartridge.....

A lighter shell will mean less brass. A heavier shell will mean more brass. (DUH, right?!?! ;))

Now, if the outer dimension is the same, the inner dimension will be different. That means either more or less "dead space" of powder to burn before pushing the bullet out of the case.

Less space, means the pressure will build slightly faster, pushing the bullet sooner.

More internal space means the pressure will build slightly longer, but will build more pressure before forcing the bullet out of the shell.

(I think i got that right.... correct me if I'm backwards. :eek:)

How OCD do you want to get? More???? Now start weighing your bullets. Also, even a few flakes of powder will throw off your consistency ever so slightly, even though your scale reads XX.X. There may be more or less powder, but not enough to change the digit (or scale weight).

Powder, primers, bullets, cartridges all matching lot numbers, and they have loads worked-up for each lot change.

Loads change at different altitudes, temperatures and humidity's.

Yes, competition shooters are particular about everything.

I might be OCD too, but i have my limits and accept my defeats. :D
 
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It depends on the rifle .

Good bullets in a good barrel are foremost.

I have a 30-06 that puts 5 rounds in .600" @ 100 yds with mixed cases, 45.0 grains of IMR4895 and 168 SMK.
I do not feel a need to tune it any farther.
 
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It depends on the rifle .

Good bullets in a good barrel are foremost.

I have a 30-06 that puts 5 rounds in .600" @ 100 yds with mixed cases, 45.0 grains of IMR4895 and 168 SMK.
I do not feel a need to tune it any farther.
That's pretty good. Even so....,
You can get away with a lot more @ 100 yds. Stretching it out further will begin to show the velocity differences/inconsistencies.
 
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That's pretty good. Even so....,
You can get away with a lot more @ 100 yds. Stretching it out further will begin to show the velocity differences/inconsistencies.
Yup.
Shot Expert scores @ Pendleton, ~20 points shy of Master with irons on the 88 round COF.
That is as good as I could hold.
 
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If you've ever gone to the range with your sack a reloads only to find the individual components, ie the primers and bullets fell out of them, you'll kinda figure it matters a little bit.
 
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I like to use cars as most people own/drive cars and at least know something about them. So....

What difference does it matter if you use high quality tires or cheapo tires? Why not bald tires? Tire are tires, right? I mean what is up with all the different treads? Different sizes, widths, makes, models, brands, what's all these crazy questions you askin' me?

Why use a brand name gasoline instead of the cheapest gas you can find? Why high test and not E-85 or E-60? Gas is gas, right?

Why tune up the engine, change the oil or use a name brand anti-freeze, isn't the off-off-off brand just as good?

Now change that to "cartridge cases", same thing. Plinking and only care if the gun goes "bang"? Most any case (in good condition ideally) that is made for that cartridge will work. May not be accurate, velocity may (will) vary widely, bullet pull will vary widely, primers may fall out allowing gas to blow out the back, but hey, the gun went bang didn't it? Good to go!
 

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