# Is This Normal for Case Stretching???



## AdamFisk (Jan 30, 2005)

I'm curious if this sounds right to you guys. I re-sized 125 once fired factory Federal 308 rounds yesterday. Once I got them polished up I started measuring each case to seperate them into 2 piles, under 2.010" and over 2.010". I was surprised at how much my cases stretched after just one firing and one trip through the re-sizer die. 3/4 of my cases measured between 2.010 and 2.015, the max case length, with 1 being over 2.015.

I fired at a coyote this morning and out of curiosity I measured that case. It measured 2.006". Granted it was only was case, but I'm assuming that is what most of my cases were around before they went into the re-sizer. Most of them came out above 2.010. Is that normal?????? Is Federal brass crap?????

Also, at what point do you worry about trimming your cases? I know max is 2.015, but would you trim them at all if they were, say, 2.014"? Lastly, what would you tirm them to???? My manual says trim to 2.005". Do most of you trim to the min csae length???

Yeah, I'm a rookie.

Thanks!!!!


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## Csquared (Sep 5, 2006)

Measure the case before and after you size it. The neck sizing button can pull pretty hard sometimes, and you may see that sizing stretches all your cases more than firing does.

I trim so that all cases are the same length, not worrying how much under SAAMI spec'd length they actually are, but all things considered actual case length is of minimal importance as long as you keep them shorter than your chamber.


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## AdamFisk (Jan 30, 2005)

I know sizing stretches these cases more than firing does. I measured my fired case from this morning, without resizing it, and it measured 2.006. Chances are if I run that case through the resizer, like I did with the other 125 identical ones yesterday, it will come out above 2.010. I'm curious if that amount of stretching is normal, or am I doing something wrong?

I do have new Remington brass I could measure, run through the resizer, and remeasure. If I get similar results, than what?


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## AdamFisk (Jan 30, 2005)

I just ran 2 new Remington cases through the resizer:

1. before 2.0045 - after 2.0052

2. before 2.0055 - after 2.0059

My Federal that was fired this morning, and measures at 2.006, now measures at 2.0102 after going through the resizer.

??????????


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## Csquared (Sep 5, 2006)

I'm not sure what the question is, I guess. I suspect there will always be some stretching as the expander ball is pulled through the neck, and I also suspect you will get similar results with other brass, but that's not a big problem since you trim after that. If you don't want to stretch cases you could use a collet type sizing die that doesn't use an expander ball to size the neck or you could switch to a separate body die and use a bushing type neck sizing die..or the bushing type neck die could be used alone and skip the resizing of the body.

I have all types but have settled on simple FL sizing for all rifles except ones with a tight necked chamber.

You'll find some get pretty wrapped up in case stretch and go so far as to adjust their full length dies to neck size only trying to work the brass as little as possible, but in my experience case necks or primer pockets fail long before I've seen any issues from full length sizing. UNLESS you don't verify how far you are pushing the shoulder back. That can separate case heads in just a couple shots, so always check when setting up your FL sizing die.

Don't know if I helped any, but good luck!


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## alleyyooper (Jul 6, 2007)

A long time ago I decided I didn't like federal brass. Way back then it seemed harder to size but streched more. Now If I come across any I trade it for stuff I like.
When sizing I use a brush set up with powder grphite to lube the inside of the case neck. It allows the expander ball to slide thru easier.
I have an Old C shaped thing they sold years ago to measure cases in a hurry. Any won't fit I set aside and when I get a couple of hundred I size them all to fit.

You can see part of the case sizer in the picture above the amp. I really should take a full picture of my bench.









 Al


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## Plainsman (Jul 30, 2003)

I doubt that the expander ball has anything to do with case neck stretch. The case stretches when the cartridge is fired. When you resize you bring those case dimensions back to specs. Where does that extra brass go. Well like water it flows to the area of least resistance, and that's forward. The resizing is what causes the stretch. If you want to prove that to yourself screw the expander ball loose and pull the case out the bottom and measure it without ever pulling the ball through the neck. With some brand dies you can do this, with others you can not. 
There are two schools of thought to when it is best to trim. In the past I would resize then trim. Now I worry about deforming the neck while trimming so I trim first. Some manuals give you trim length before sizing and trim length after sizing. My older Hodgdon manual says trim to 2.005 and gives maximum case length as 2.015. I know that a case fired three times will not move as far forward after resizing as one fired only once resulting in slightly different case lengths. However, my 308 regularly shoots under 1/4 inch and that's good enough for me. Sorry, I even violate the rule of keeping once fired brass separate from twice, and twice from brass reloaded five times. I only separate by case brand. Before I even polish I check for head separation. 
I reload many brands of brass, but in my 300 Winchester mag Federal is all I have loaded for 12 years. Once I hit groups of .3 inches and under I hate to change anything. The other thing I often see people complain about is CCI primers, but my 300 mag just keeps punching ragged holes with Federal brass, CCI primers, R22 powder, and Ballistic Tip bullets. The bullets I have often played with, and Barnes X bullets and Swift Scirroco shoot right in there with the Ballistic Tips. I got brave last week and purchased 50 Winchester brass. When it gets a little nicer I will find out how they work.


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## Fallguy (Jan 23, 2004)

I am also a rookie but I was taught to resize then trim. I trim all my cases so they are all equal to eliminate a variable in differences. I use the Lee Case trimmer with my drill chuck and just trim to what the rod determines. Seems to work.


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## AdamFisk (Jan 30, 2005)

That Lee trimmer your talking about, I picked one up but have not used it yet. That's not adjustable is it? If I wanted to trim to the min case length, I couldn't with that, correct?


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## Fallguy (Jan 23, 2004)

Yeah it is just one length.


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## xdeano (Jan 14, 2005)

If you want a case trimmer that will give you perfectly trimmed case mouths go with a Wilson case trimmer. You can trim to what ever length you want to. I usually trim all cases the same, I write it down, then then next time I reload I can just cut to that same length again. It acts like a concentricity gauge as far as the brass being on rails. http://www.sinclairintl.com/product/5494/Case-Trimmers You have to buy separate holders for the brass but they are machined so you get a perfect cut every time.

Federal brass is junk. It's good for about 3 or 4 firings then it's spent.

I'll agree with Plainsman on the resizing button on FL sizers, it's just opening the neck up to specs. The flow of brass is caused by compression of the brass in the die. I use a bushing die on my brass then I cut to length. I think my cutter is set up to 2.010" so kind of in the middle.

xdeano


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## xdeano (Jan 14, 2005)

Alleyyooper,
Sinclair makes a similar tool that you described in your post. 
http://www.sinclairintl.com/product/7940/Case-Gauges-Headspace-Tools

xdeano


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## Csquared (Sep 5, 2006)

Hey Plainsman and xdeano......

Plainsman's mention of brass getting longer as it gets thinner is spot-on accurate. But don't forget the inverse is also true. Perhaps we should explain the difference between brass growing, or flowing, and actually stretching brass. More on that later, along with my apology to Adam for accidentally causing this discussion to get much deeper than necessary. 

One important point in Adam's post is that all cases in question HAD BEEN FIRED IN HIS RIFLE PREVIOUSLY. That's a very important point. New brass is very undersized, and as such oftentimes barely contacts a FL sizing die other than the case mouth. But once that case has been fired in a particular rifle it becomes a tool used to identify the intricate details of that particular chamber. So knowing the cases all started as fire-formed to Adam's rifle, and then FL sized with Adam's die, when they were subsequently FL sized with the same die and settings for the second time they were simply returned BACK TO THEIR PREVIOUS SIZE...not "made smaller" as indicated by Plainsman. So any added length to those cases, assuming no affect by the expander ball, is there ONLY AND SOLEY DUE TO THE FIRING OF THE CASE, not the sizing.

Please correct me if I'm wrong, but assuming you push the shoulder back during resizing so that there is .005" space between the chamber shoulder and the shoulder of the case, immediately upon firing the brass will _STRETCH _.005" to fill that space. At the same time it is expanding to fill the space left between the chamber walls and the case. As soon as the case completely fills the chamber brass continues to _FLOW_ forwards due to the intense chamber pressure. When that case is sized, again ignoring any possible affect of the expander ball, it is returned to EXACTLY (in Adam's example) the size (excluding length) and shape it was before it stretched and flowed inside the chamber. The difference in length after the second sizing compared to after the third sizing shows you exactly the total amount that case flowed and stretched when it was fired.

The sizing _revealed_ the added length, but did NOT create it.

If I'm wrong, please explain. I can take it!


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## Plainsman (Jul 30, 2003)

I don't know what the ratio would be, between firing stretch and resize stretch. When a case is fired it stretches in diameter and length. Small Arms Manufacture Industry specs allow for .005 inch chamber variance. For reloads to fit in all chambers full length dies must reduce case size to fit in the smallest chambers. If a rifle is minimum spec you may get ten reloads because there is little stretch and reduction in size during full length sizing. If a rifle is near maximum spec expect to get only two or three reloads from a case.
Cases stretch upon firing, but when they are full length sized the neck does move forward. To prove this to yourself measure a fired case, then resize and measure length again. Some manuals have a maximum length for those who resize then trim, and they also have a trim before resize specification which is normally .010 inch less. Hence what I mean by made smaller while sizing is that the case is resized back down to the size of the die which has to be smaller than the size of the chamber it was fired in.
I once sent a 308 in and had the barrel set back and rechambered to minimum spec. Some factory rounds would not chamber. I had to send it back in and have the chamber cut another .001 inch.


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## Csquared (Sep 5, 2006)

How are you trimming? I'm unaware of any trimmer pilots sized appropriately to fit properly prior to the sizing of the neck.


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## Plainsman (Jul 30, 2003)

I am using a Lyman trimmer with a cordless drill. Yup, it's slightly loose, but it's no problem if you don't have cases that are really stretched bad. In heavily stretched cases you will get some brass turning over and binding as you pull the case free. I have sized, then trimmed, then sized again. I worry about that wobble in the trimming causing slight deforming of the neck. I have never been able to get a perfect trim going without some wobble in the trimmer.

Maybe I should look at a new trimmer. Trimming after sizing leaves a nicer edge to the neck. Others must trim like I do though because the Hodgdon manual has trim to length before sizing dimensions.


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## texcl (Oct 6, 2007)

The hotter the load the more the case will stretch when sized since there will be more resistance during sizing and the fact the case just streches more during the firing cycle. I used to use a real fancy bench mounted case trimmer but now I use a drill mounted lee case trimmer since it is so much faster and far easier to set up and there is definetly not difference in accuracy between the 2. I trim all my new and once fired cases since I have found huge variations in length. Federal brass is low on the list of good brass, I shoot an AR-10A4B and it is pretty hard on brass, I've found that I can get twice as many reloadings out of winchester brass over federal, the Federal brass is softer and easier to work but it shows the effects of pressure sooner. Right now I'm sitting on several hundred surplus casings that are made by lake city which is the military division of federal and that brass is better than federal commercial but not as good as winchester.


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## headshot (Oct 26, 2006)

I always trim after FL sizing.... That's how you get your best results. I don't leave anything to chance when I am reloading hunting rounds.


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## Plainsman (Jul 30, 2003)

headshot said:


> I always trim after FL sizing.... That's how you get your best results. I don't leave anything to chance when I am reloading hunting rounds.


I have always wondered which is best. I think it depends on the trimmer that you have. I think I will get a new trimmer. I have a Lyman now. I checked out the Redding yesterday. Normally I like Redding loading equipment, but I certainly don't like their trimmer. I think I will go with an RCBS. 
The reason I trim first is my trimmer. The brass is not held securily enough, or straight enough in the trimmer. Sure the pilot holds the front, but there is still wobble at the back, and that causes the front to also turn out of balance. I think I like the way the RCBS holds the brass.
When I have ever sized first I have always lost confidence in accuracy and sized a second time after trimming.


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## Csquared (Sep 5, 2006)

I encourage you to consider Forster before you buy Plainsman. The collet type chuck is virtually fool-proof. I think you know I LOVE RCBS, but you should at least consider Forster or Wilson.



> The hotter the load the more the case will stretch when sized since there will be more resistance during sizing


Hey texcl.... If sizing is what stretches the case, why do hotter loads stretch em more? And unless you're talking so hot that you bulge the casehead, how do hotter loads contribute to increased resistance during sizing?

Please explain.


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## Csquared (Sep 5, 2006)

Looks like no explanations are forthcoming so in closing I'd like to post this for discussion.

The crux of this thread stems mainly from word interpretations. "Stretch" is not a word I think can be used to describe anything that happens during the sizing operation unless you are trying to determine if the expander ball has actually pulled on the neck as the case was withdrawn from the die. If that did occur, the added length would most likely come from a reduction in diameter but slight increase in length of the shoulder area of the case. The case would measure slightly longer in that scenario simply due to the fact the neck was pulled in a direction opposite it's support, or a classic example of "stretch". That concept was clearly explained by Plainsman above.

But to say any other part of the sizing process "stretched" a case, I feel, would be inappropriate. The sizing operation simply _displaces_ brass, or as also stated by Plainsman, relocates it to the path of least resistance. But I do not believe the sizing process "borrows" any brass from elsewhere in the case, which is what* MUST* happen to add length if it's diameter remains a constant. But firing the case does. When we hear talk of checking the thinning of the case at the web area for the potential of casehead separation, by doing that aren't we acknowledging that the added length has been "borrowed" from the web area by way of actually _thinning_ the walls of the case in that area? Which further illustrates that the actual growing of the case is done while firing, since no matter how hard you push on your press handle I doubt you will EVER be able to replace case wall thickness lost at the web when the case was fired. In short, 6000 degrees and 60,000 pounds of chamber pressure redefines "brass flow" when compared to the palm of your hand pressing on the handle of your press. :wink:

You may think this is somewhat off-topic to discuss at such length (no pun intended  ) why a case grows, but I believe a disservice is present here by infering that FL sizing is so detrimental to case life. It was mentioned above that one could expect only 3 firings in some rifles before cases would be relegated to scrap. But I submit that in a properly set-up die the case will fail in places barely affected by the sizing operation, and affected equally whether FL sized or neck sized only, and the lifespan of that brass will be determined more by it's quality...not your sizing preference.


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