2 brass questions ?

[Willyp]

#1-Have you ever had rifle brass shrink? I mean come out shorter than before it was fired?
#2- I bought some brand new Remington 30-06 brass,over a year ago or more,when it was hard to find! It came from Midway.As you most likely know, the Max length,of this cartrage is 2.494 and trimmed to 2.484.
The new brass had about 15 or 20 of them,out of the bag,at 2.479? I figured they would stretch after fireing,but they didn't! Also some of them seem to have shortened down into the 2.479 length? [ How short can they be before you would not use them?]They make for very inaccurate shooting!
Am i crazy or is there something here i don't understand?????
The guns i am shooting are pretty new Savages i have bought in the last 5 years and were brand new!

[13Echo]

A case expanding into a large chamber may come out shorter than it went in. The case will usually regain length when full length sized. If the cases aren't too long to begin just square the mouth. Wait to trim till a full length sized fired case exceeds your limits. Cases for rifle should be checked for length after each firing.

My two bits.

[Litl Red 3991]

#...............They make for very inaccurate shooting!


Often when mixed with other lengths.

Marking them and keeping them separate is one thing to try. But test them for accuracy to be sure.

Measuring their ODs is worth doing. And check how thick the brass is too, if you can. You might discover why they're shorter. Comparing weight just might tell you something too. Your short cases just might weigh the same and good ones, and yet weigh the same. It'd tell you the factory was checking for uniformity by weight, and let some that should have been rejected pass with thick walls.

[str8wal]

As long as the shoulder is correct, I don't see where .005" from there to the case mouth should make much of a difference in accuracy.

[Willyp]

As Litl Red says,i will keep the short one seperate,but most likley just junk them?
Str8wal,it is or was from them being mixed in and fired with the regular lenghth brass! It did make a lot of difference in the grouping. The short ones were all over the target! This happened to me twice,with these cases! I thought i had a bad can of powder??????
The way i found that they were short was i use the Lee case trimmer gauges [after full lenght sizing them] and the cases were way to short.

[Litl Red 3991]

If there is a roll crimp required, the length of the case is going to affect the crimp. That's going to affect the ignition which is going to affect the velocity. Some more... some less...

[Litl Red 3991]

When you get any brass that has a significant difference of any kind, there is a good chance (or maybe it's really a bad chance) there is more than one difference in each case that shows that difference.

[str8wal]

If there is a roll crimp required, the length of the case is going to affect the crimp. That's going to affect the ignition which is going to affect the velocity. Some more... some less...

Ahhh, I don't crimp bottleneck cases so that thought wouldn't have occured to me. If crimping, like I do with straightwall cases, I understand the difference there.

[Motor]

It's actually normal for fired cases to be shorter. The case has to expand to chamber size. When it does it draws the length in. When you resize the case it will grow. Sometimes it grows enough to need trimmed.

RCBS requires you to trim cases that are going to be used for their X-DIE to .020" under max. I use the X-DIE for 30-06 so my cases are trimmed to 2.474" after the initial sizing.

I haven't looked up SAMMI spec for 30-06 but do know for a fact that for .223 the tolerance is +0/-.030" this along with the fact that RCBS instructs to trim the 30-06 to 2.474" I'd have to say you are perfectly fine at 2.479"

As someone already stated varying case lengths will have little effect on anything unless you are crimping. Then if you are using a Lee collet type FCD you still can get away with some variance in case length.

Just as a side note: Too long is NEVER good. A little short is typically not an issue as long as you have enough to support the bullet.

I used to compete with a .280 Rem. The max case length is 2.540" I used to use GI 30-06 brass converted (fire formed) to compete with. Needless to say especially since I neck only sized, I never had to trim my brass. :)

Motor