Brass - Normal or Crazy

Vern

Vern

Morethan1waytoskinacat
I was just checking some brass.
Its been fired 3 times.
After firing the length is 1.486 after sizing length grows to 1.490??????????
Shoulder bump is right at 1/2 thou.....0005
Case shoulder size after firing is .4325 after sizing it is .4290

Is this normal. I guess I have never noticed or compared these areas or things at these particular times.

Edit to correct typo
 
Last edited:
Normal. Any time you squeeze down a case, the brass has to flow somewhere. That somewhere is usually in the length. Picture a baloon that you squeeze in the middle.

ray
 
Thats what I thought Ray but I guess I never did a good before and after and paid attention. I just thought .003 in length increase seemed excessive.
What about the shoulder body area is that about the right amount of decrease?
It would seem if I am increasing the length .003 just by sizing that maybe my die isnt right for my chamber. I thought it was by all accounts in measuring other areas but now I am beginning to question myself again.
 
Ray,
I disagree. Thirty thousandths of case growth is not normal, particularly with that few firings and sizings.
Vern,
Are we talking about a 6PPC? What die? Are the measurements that you call case shoulder size made with a gauge that measures what has been referred to as case "headspace", if not, how are your measuring? The difference in measurements is significant....three and a half thousandth...too much if it represents your bump.
 
Boyd

He's not just bumping, he's also sizing the case body. I assumed he measured the shoulder diameter with a caliper or mic. If the shoulder was sized down, so was the rest of the body, I would guess. How would you account for the increase in length from nothing more than FL resizing? He's not measuring before and after firing.

Ray
 
typo on my part 3 thou in length
I am trying to just barely bump.
Thats why I am only at about .0005 for the bump, less than 1 thou
Edit
Yes Boyd its a 6ppc
 
Boyd as to the measurement when I use a head space gauge I am only moving the shoulder back 1 thou or less.
The measurement I was talking about is the shoulder body junction width.... if that makes sense.
As in how much it reduces when I size.
 
I had the measurements typed wrong for that area. Added 1" for some reason.
Sorry.
 
Vern said:
I was just checking some brass.
Its been fired 3 times.
After firing the length is 1.486 after sizing length grows to 1.490??????????
Shoulder bump is right at 1/2 thou.....0005
Case shoulder size after firing is 1.4325 after sizing it is 1.4290

Is this normal. I guess I have never noticed or compared these areas or things at these particular times.

Edit to correct typo
Click to expand...

So it sounds like the trim length grows 4 thou? And I assume you meant that the diameter of the shoulder is .4325" after firing and .4290" after sizing?

If this is the case, then I'd say the brass is growing too much from being squeezed too much. You're taking the shoulder diameter down three and a half thou which is double what you really need. I'd bet your squeezing in the web area too much too.

It depends on how hot of a load you run and a myriad of other factors, but typically, if you squeeze your web diameter in .002" and the shoulder diameter in .0015, and you run "normal" loads, you should see maybe .001 to .0015 worth of growth after three firings. Sometimes not even that much.
 
Guys

He's not seeing the growth from firing. It's coming from sizing. 3 or 4 thou from body sizing is perfectly normal.

JMHO

Ray
 
Size without a bushing, and measure the growth! Shouldn´t be to much...

When you use a ~.003" undersized bushing on the neck, the brass has to flow somewhere. When you seat the bullet, the brass will decrease in lenght when the bullet expands the neck.

//Peter
 
Cheechako said:
Guys

He's not seeing the growth from firing. It's coming from sizing.
Ray
Click to expand...


That is why I said this:
If this is the case, then I'd say the brass is growing too much from being squeezed too much.


I'd agree that .004" of growth is normal for off the shelf dies in off the shelf guns chambered in "factory" specs. But it's way too much for a competitive 6ppc with matched dies and chamber.
 
I am at work now so last post til 4 am tuesday.
The neck is .269,
GG I dont know how much it is squeezing the web but as I remember its not moving the web enough to tell.
BUT I will check it tomorrow.
What caused me to realize the length issue was that last year it didnt seem to get long enough to hardly trim.
Today I had some primed cases next to fired ones from the last match.
I checked the fired ones and was disappointed that they still didnt seem to be where I wanted them so that I could trim to the length I wanted.
But when I measured the primed cases they were certainly long enough....
Guess I just never noticed before.
 
OK, now that the information is sorted out, clarified, and clarified, I am pretty sure that the real culprit is the reduction in diameter of the shoulder. I have a Harrell's Vari-Base die that does not reduce the diameter of the shoulder at all. One thing that I have noticed is that case growth from sizing is very small. Size one with your usual bump, without the bushing, and let us know what you get.
 
Your squeeze is not making the case lengthen. If you are using a FL size die with an expander ball, the expander ball(button) is stretching the case neck about .003 each time you size it. A bushing die without the expander does not lengthen the case.
 
zimmden

Vern didn't say anything about using a die with an expander ball but if he is, that's what's causing the lengthening. I just assumed that since this is a Benchrest Forum he's using a neck bushing in a shoulder bump and body size die.

That kind of die requires very careful adjustment because if you bump too much it will cause the body to pook out and you have to size it down in order to chamber the cartridge. Going in the oposite direction, if you size the body down too much it will cause the shoulder to pook out and you'll have to bump it back in order to chamber the cartridge.

Squeezing any part of the case is going to cause it to get bigger in another spot.

Ray
 
zimmden said:
A bushing die without the expander does not lengthen the case.
Click to expand...

I couldn't disagree more.
I wonder if you're aware that the vast majority of BR shooters use bushing dies without expanders, and that most, if not all of us, pack trimmers to the range and use them frequently? If bushing dies without expanders didn't lengthen cases, we'd certainly leave the trimmers at home.
 
Boyd Allen said:
OK, now that the information is sorted out, clarified, and clarified, I am pretty sure that the real culprit is the reduction in diameter of the shoulder. I have a Harrell's Vari-Base die that does not reduce the diameter of the shoulder at all. One thing that I have noticed is that case growth from sizing is very small. Size one with your usual bump, without the bushing, and let us know what you get.
Click to expand...

It very well could be that just the shoulder is the culprit here. I have two dies that size the shoulder too much on a standard .432 diameter brass but don't touch the web area enough on a .440 standard dimension chamber. Redding is famous for making the shoulders too small and the bases too big. I've even got a SB Redding that actually does size the web enough but still squeezes the shoulder too much. If you want truly custom fit relationships between your brass and your chamber to avoid case length growth or other problems, you've either got to have custom dies made or a custom reamer made. Or, get a Harrells Vari-base like what Boyd has! Wish they still sold those............
 
OK to add to and also clarify.
I dont ever have excessive brass growth. Just the opposite I could never get my brass to grow enough last year to be able to trim it to length.
I usually use 50 cases at a match so they only get resized 1 time a day.
And I usually have to have 2-3 resizings in order to have enough to start to be able to trim and then sometimes it is not even all the way around.
I use a standard bushing type die.
I bump the shoulder .001 or less never more.
This time I just found it odd that the brass grew .003+ after being sized.
I did check the bump and it was a little over .0005
I just figured maybe it was something I never noticed before.
I can shoot 50-100 cases for a whole season of club matches and have never had any problems with cracks or separations or excess growth.
 
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