Case Length - The bottom line???

[gottarollwithit]

So i'm just beginning to load .308. I'm using once fired Federal American Eagle brass. I'd like to figure out what exactly to do before i get too far along.

What's the truth regarding case trimming? I've been told that if it's only once fired, you can use it again without trimming it down.

The textbook max case length is 2.015". My once fired brass runs 2.017 or so. They're all within a few thousandths.

What happens if my case is too long? Will it be ok to be a few thousands above the max? What if it's a bit too short?

I've been scouring the net and have found different answers. From what i understand, if it's too long it the cartridge just won't chamber all the way. If it's too short nothing will happen. Is this correct to assume? I've come to the conclusion that it's usually very bad to break maximum's around here.
Or, is case length more determined by my gun than a textbook?

Thanks again!

[CSACANNONEER]

Case length is determined by your chamber. Have you done a chamber cast? If not, you should assume (I know) that your chamber was reamed within specs and you should follow the book. You really should trim every time you proccess the brass. Consistancy in your brass prep has a lot to do with consistancy of your finished product.

[dustoff31]

What CSACannoneer said.

Look at it this way, you can always run something a little out of spec and it will usually work OK. But sometimes it won't. If you intend to fire the ammo out of more than one rifle, the more important it is to stay with the proper demenisions.

[eaglemike]

Ummm, it looks like two different things are being discussed. There is case length, and there is headspace. Sometimes they are the same, sometimes not. In rifle cartridges, headspace is usually (in the cartridges most discussed here) not the same as case length.

You could have case length in tolerance, and headspace so long that it won't chamber, or so short you'd risk case separation. Take a look at the spec's in a reloading book. I really like an older NRA book I have, as it has both the chamber specifications and the case and loaded round spec's.

It's a good idea to only size the cases just enough to chamber easily in your gun. You can adjust the sizing die to do this. If you size the case too much, several things can happen, including the separation, or even going so far into the chamber the firing pin can't hit the primer hard enough.

Semi-auto arms usually require more sizing than bolt guns.

There's a lot more technical info that can be discussed, but I'm a challenged typist, and other writers have discussed thing more more completely than I can. Get a few reloading books, and be sure you understand what they say.

More things to think about reloading bottlenecked rifle stuff compared to straight walled pistol stuff.

all the best,

Mike

[gottarollwithit]

Interesting. I'll have to borrow a reloading book soon.
I shall trim everytime i resize the brass then. Just trim it down to 2.01"?? Any recs?
I'll be using the ammo in 2 different bolt guns.

[eaglemike]

In bolt guns, I'd for sure buy a set of the Lee collet dies. Way easier to use, and work the brass less. You'd also need to trim the brass a lot less.

Depending on where you live, you might be able to borrow a couple of books.

all the best,

Mike

[Splinter]

I usually get 2 or 3 firings out of my cases before they get out of spec. Some brass is softer, some is harder and stretches less. I would say measure everytime, trim when necessary.

[gottarollwithit]

Call me crazy, but i measured some of the AE brass before resizing and after.
On a few there were no change and if there was change it was less than a couple thousandths of an inch.

I'm gonna just measure all of them and trim them to 2.01". Is this a good place to trim it down to?

[eaglemike]

The measuring and trimming is after sizing.... Sometimes the stuff doesn't move much, especially in bolt guns.

all the best,

Mike

[rksimple]

You don't need to trim after every firing. Not necessary at all, even for excellent accuracy. Just trim them .010 under max, as always, and load away. You'll find that Federal brass sucks. Its quite soft and the primer pockets will open up with any sort of med-warm load. Expect 4 loads max, unless they're light.

[Prc329]

You don't need to trim after every firing. Not necessary at all, even for excellent accuracy. Just trim them .010 under max, as always, and load away. You'll find that Federal brass sucks. Its quite soft and the primer pockets will open up with any sort of med-warm load. Expect 4 loads max, unless they're light.

I've had a few pop primers out after 2 reloads on a text book load.