reloading question. case growth

[vujade]

hello.

I'm reloading 308. Federal cases.

Question -

The length of factory cases (not fired yet) are between 2.007 - 2.010 inches (Federal and Hornady cases).

Once I fired them and put them through station 1 of a Dillon, they have grown to 2.021 to 2.027. My question - Is that normal "growth" after just 2 firings (the shot when shooting them as factory loads and the 2nd shoot after shooting them as the first reload)?

If the manual says case length should be 2.015... does that mean it's not safe to fire them if they are longer than that and I should always trim them whenever they are over 2.015?

thanks guys!

[R_Bert]

yes, max typically 2.015" - 2.020"

Go ahead and trim to 2.005" *after* resizing

Here are the SAAMI Specs

http://www.saami.org... Winchester.pdf

Edited June 6, 2012 by R_Bert

[Dolomite_supafly]

If you seperate the steps you can make your brass grow less and last longer.

I use a neck sizing die for one step then a body die for the other step. I used to get 4-5 loadings on my 223 brass but now I get much more. Right now I am over 10 loadings without any noticeable problems.

Dolomite

[gregintenn]

I like to trim every case each time it is loaded, just so they are all consistant, and so one that is too long doesn't slip past me. It stands to reason that the closer to the same each round is, the more accurate it will be. That starts with the cases.

[Dolomite_supafly]

I trim every 3-4 loadings on my 223. It shoots sub .4" groups at 100 yards consistently. It has also shot enough .2" groups that it isn't a fluke.

I guess I need to put that barrel back on seeing how I haven't shot my 7.62x39 barrel for accuracy yet.

Dolomite

[vujade]

thanks guys.

Dolomite... in a different thread, you had mentioned something about installing barrels and that you minimize headspace and that makes brass 'grow less'. (forgive the rough paraphrase). This much case growth isn't a sign of that is it?

In other words, it's within reason that a case can grow this much after only 2 firings?

I also didn't know they have separate neck/body sizing dies. (mine is the one that does the neck, body and pops the primer out)

Thanks _Bert. I'll cut it AFTER I resize. That makes sense.

[leroy]

vujade:_____________

Back in the "old days" when we shot bolt guns only; we only neck sized the brass we were reloading and kept the brass separated by each individual rifle. That meant that the brass was, in effect, fitted to each individual rifle's particular chamber. We only neck sized the brass when we reloaded it. The problem of "brass growth" is related to pushing the shoulder back on the case each time you resize. The "growth" occurs when ya shoot the round and the brass shoulder moves forward a tiny amount (..."grows", if you will...) to completely fill the particular rifle's chamber each time you fire the round.

The problem is that this trick doesnt work too well with semiauto rifles that need a bit of "slop" between the round and the chamber to operate reliably. If i wuz loading for a semiauto i would invest in a good "drop in" type cartridge gage and set up my dillon to do a minimimun resizing that would pass the gage.

I like Dolomite's solution given in post #3 above. (...I would run the brass thru a single stage press for the sizing and load on the dillon; backing off the sizing station on the dillon...) It appears that Dolomite's method doesnt allow the shoulder to get pushed back; ala the old time way for a bolt gun with the extra sizing needed for the base (...which i like better than our old method...). It sizes the brass at the base and at the neck; while leaving the shoulder of the brass alone.

I've got a pile of 300 win mag at home that needs either trimming or scrapping because of this. The problem was that i wuz too lazy to keep the brass separated between my ruger #1 and an old remington 40x.

Hope this helps a bit.

leroy