PDA

View Full Version : Not sure where this should go so....



TonyM
10-15-2010, 01:06 AM
We'll start here I guess.

Anyone ever notice any variances using *NEW* brass vs. Fired/sized brass regarding accuracy?

geargnasher
10-15-2010, 02:12 AM
State of case neck anneal and consistency therof has a great deal to do with accuracy. A fresh anneal often blows groups unless the case necks are work-hardened by a few extra strokes through a sizing die with an expander ball installed. Comparing 1F to brand-new brass I can't say there's much difference with the same headstamp, often there is more difference between two different brands of brass of the same "experience" than with one or two firings apart on the same lot.

So what is it that you're really trying to discover?

Gear

waksupi
10-15-2010, 02:16 AM
I've always had better accuracy after once fired. I only partial neck size, so the case is fire formed to the chamber on subsequent loadings.

x101airborne
10-15-2010, 08:18 AM
i have done that on my bench rifles for years. I usually buy a couple boxes of bullets (anything will do) in that caliber and just burm them. then resize the neck 2/3 of the way down in a redding competition neck sizer and reload. Very concentric, but very fragile. Dont drop them as it can cause MASSIVE alignment problems. But very effective in at least the 6.5x284.

Shiloh
10-15-2010, 08:36 AM
I concur what Gearnasher said about annealed brass. It takes a few strokes with the sizer and expander, plus a firing or two. I anneal when the case necks becomes to springy. I have both '06 and Krag brass that has to many firings to count. My split necks have been greatly reduced, or are completely non existent.

Shiloh

Pepe Ray
10-15-2010, 09:08 AM
I hope this question is relevant to the subject and the O.P.'s ?

We have various lead hardness measuring instruments. An instrument to measure the brass cases would be valuable.
Call it springiness, ductility, hardness or whatever, it's a **** shoot trying to decide when your cases need annealing. With the rising cost of metals, an ingenious entrepreneur could make gas money from us with such a tool.
Or perhaps a "process", a technique using commonly available tools to measure the need for annealing.

My imagination leads me to crushed necks.
Pepe Ray

44man
10-15-2010, 09:53 AM
We'll start here I guess.

Anyone ever notice any variances using *NEW* brass vs. Fired/sized brass regarding accuracy?
New brass should be sized before shooting anyway.
But your question is not clear as to the gun. I would say the revolver is the worst with new brass because neck tension can vary too much although Starline might be closer.
The reason is the revolver has no rifling near the boolit to retard movement before good ignition.

cbrick
10-15-2010, 11:08 AM
Anyone ever notice any variances using *NEW* brass vs. Fired/sized brass regarding accuracy?

Welcome to Castboolits Tony,

What kind of brass, bottleneck? Straight? What platform are you using to determine possible variances? What possible variances are you looking for? How many times fired/sized?


New brass should be sized before shooting anyway.

But your question is not clear as to the gun. I would say the revolver is the worst with new brass because neck tension can vary too much although Starline might be closer.

New brass, twice fired brass, various crimps or NO crimp. Following is a test I did some years ago to compare the effects of these changes with the chrono. This can give the grey matter something to chew on. Draw your own conclusions from this, what I do for major matches in long range revolver is use virgin not sized brass with a profile crimp. All other matches I use fired, sized brass, profile crimp. All brass that will be crimped is of course uniformly trimmed to length. All brass had the flash hole and primer pocket uniformed with Sinclair tools.

Crimp Tests
FA 357 Mag 9”
RCBS 180 GC Silhouette @ 192 gr. (WW + 2% Sn, oven HT @ 18 BHN)
16.0 gr. H-110
Winchester brass
CCI 550 primer
Temp 70 Humidity 38%
All chrono tests 10 shots

1> My normal profile crimp, second firing of WW brass, Carbide die sized
E.S. 30
A.V. 1518
S.D. 9

2> Roll crimp, second firing of WW brass, Carbide die sized
E.S. 30
A.V. 1520
S.D. 9

3> No crimp, second firing of WW brass, Carbide die sized, very slight bell
E.S. 30
A.V. 1528
S.D. 9

4> Light profile crimp, virgin WW brass, not sized, not expanded, slight bell only
E.S. 26
A.V. 1532
S.D. 8

5> My normal profile crimp, virgin WW brass, not sized, not expanded, slight bell only
E.S. 26
A.V. 1536
S.D. 8

Is revolver the worst with new brass? Not from my testing as long as the brass is correctly trimmed and prepped. These results may or may not answer the OP's question, these test results are with once and twice fired, once sized brass.

Rick

TonyM
10-15-2010, 11:42 AM
Wow... thanks for all the responses guys.

I'll try and answer some of the follow up questions...

The brass I try to use exclusively is starline. I buy a lot of NEW brass, and haven't had any issues just loading it and going (This is for a 454 casull and 458 SOCOM).

However, I have read that using new brass can effect accuracy... but I guess I didn't understand why. The case lengths are all within tolerances, the primer fits fine, etc.

I have had some inconsistencies at the range recently, and I was wondering if the introduction of all the new brass may have had something to do with it...

Sounds like new brass should be sized before being loaded?

cbrick
10-15-2010, 12:06 PM
The brass I try to use exclusively is starline. I buy a lot of NEW brass, and haven't had any issues just loading it and going (This is for a 454 casull and 458 SOCOM).

However, I have read that using new brass can effect accuracy... but I guess I didn't understand why. The case lengths are all within tolerances, the primer fits fine, etc.

I have had some inconsistencies at the range recently, and I was wondering if the introduction of all the new brass may have had something to do with it...

Sounds like new brass should be sized before being loaded?

Primer fits fine? Not speaking of expanded pockets but rather primer pocket depth, I uniform the depth for consistency.

Case length within tolerances, my tolerance for crimped revolver match brass is .001".

From your post that I highlighted in bold it sounds like your mixing your fired brass with new brass, is this correct? I'll bet that would show up at the range as inconsistency. I never, never, never mix brass. New brass goes into an MTM box and that is it's home, it is never mixed with even a single piece of any other brass. The only time it's not in that box is when it's either in the gun or in the tumbler and then it goes back in the same box. The box is labeled with how many times the brass in that box has been loaded.

Most people I think size new revolver brass, read the chrono results I posted above and draw your own conclusions.

Did I mention that I never mix brass?

Rick

TonyM
10-15-2010, 12:32 PM
well... seeing how the new brass has already been fired... along with the 2-3-4-5 fired brass... should I isolate it now?

I typically do not phase my brass like that... I just watch for signs of degradation in the case. I have read guys getting well over 10 loads out of the 458 brass... and I've got 500 pieces of that stuff floating around in various phases of fireing.

However, recently was the first time I didn't use either all fired brass, or all new brass... and I thought that might be what I was experiencing inconsistency wise... and I guess its sounding like that may be it...

cbrick
10-15-2010, 12:48 PM
Actually I take the not mixing brass a step further. When I load a box of revolver brass I load the entire box, that brass does not get loaded again until every round in the box is fired, then I reload it. This way every piece of brass in that box has been loaded and fired the same number of times.

Rick

geargnasher
10-15-2010, 02:30 PM
I hope this question is relevant to the subject and the O.P.'s ?

We have various lead hardness measuring instruments. An instrument to measure the brass cases would be valuable.
Call it springiness, ductility, hardness or whatever, it's a **** shoot trying to decide when your cases need annealing. With the rising cost of metals, an ingenious entrepreneur could make gas money from us with such a tool.
Or perhaps a "process", a technique using commonly available tools to measure the need for annealing.

My imagination leads me to crushed necks.
Pepe Ray

What you're looking for is called Irwin "Vise Grips" and a micrometer. I read about this somewhere recently, so I'll pass it on as I understand it, I haven't done enough of it myself to be a qualified expert, but it looks promising.

Here's what I've been doing: Adjust your Vice Grips to, when fully closed, "just" squeeze the neck of a brand new or once-fired case until you exceed the elastic limit of the brass and it remains slightly elliptical by a couple thousandths. Record these readings and compare to a twice-fired case, and so on to track how much spring the case necks gain. You should notice that with repeated firings the neck can take more and more deformation and still spring back round. At a certain point, the neck will be so hard it won't hold the boolit well or consistenly in tension, and that's where accuracy can fall off and the necks split. An anneal often goes too far the other way, making the necks too soft and inconsistent with boolit tension. Right in the middle for a couple or three firings is the "sweet spot". After you've run a batch of brass through the full cycle of resizing until too hard, annealing, and sizing/shooting back to correct hardness while checking neck elasticity at each firing with the Vise Grips and mic', you will be able to accurately track the condition of your brass.

Gear

HangFireW8
10-15-2010, 09:13 PM
Anyone ever notice any variances using *NEW* brass vs. Fired/sized brass regarding accuracy?

Yes.

For one thing, you're likely to get a different head space (depending on exactly how you size them), which (for non-rimmed brass) can affect your bullet jam or jump to throat, which can affect your accuracy.

For another thing, even full length sizers leave the mid-section of the fired brass a little fatter than new brass, which can affect axial position, which affects the start alignment of the bullet, which affects accuracy.

Does all this really matter for cast bullets? Depends. It does matter in my very best j-word .222 loads.

-HF

leftiye
10-15-2010, 09:47 PM
cbrick, Could the new brass just be tighter? Much of my new brass comes very undersized. Wouldn't a pass with the correctly sized expander ball yield more uniformity? If it's the tightness of the grip that yields the smaller ESes and higher velocity? Maybe use a smaller expander ball on both the new and fired brass?

fecmech
10-16-2010, 11:39 AM
Just a thought but new brass does not have any bullet lube in it from previous firings, tumbling does not get it all out. I have noticed a difference in bullet seating effort with new brass versus previously fired brass, it's slight but noticeable. This could make a difference in bullet pull.

44man
10-16-2010, 02:52 PM
I have made at least 20 new brass tests with the .44 since I started shooting IHMSA years ago and still have done it for hunting. I have learned a lot and I have to ask if 2 loadings is better then 3? No, it is only each piece of brass that counts so making sure each is loaded the same number of times does not solve a thing because each piece is still different although fired brass will even out a lot.
This is a test shot with 50 new cases with a scope at 50 yards from bags. At least 7 different POI.
Then a group shot at 200 yards with .44 brass shot 40 times----YES 40. Original brass from 1982.
My brass is mixed so bad with loadings I could never count it. Some loaded 10 times, some 20, some 40. I gave up the counting thing long ago. I just hate new brass for the revolver.
Anneal for the rifle but did you know a few degrees from case to case will change group size?
Brass is so important for accuracy, you can flop big time or shoot like never before.

Doc Highwall
10-16-2010, 03:41 PM
I just bought some new Lapua 308 Win Palma brass with the small rifle primer pockets and .060" flash holes and when I loaded them the first time I ran them all in a Redding Competition Bushing neck sizing die. Then used the expander die with the floating chamber and expander that I designed and the felt pressure was all over the place. Now that all of the 300 cases have been once fired in my rifle I have just reloading the first 50 and it was alot smoother both with the neck bushing and more so with my expander. I think now that the cases fit my gun's chamber that the accuracy will be better because the bullet pull will be more consistent.

cbrick
10-16-2010, 06:08 PM
Yeah Doc, that's pretty much what I do with bottle NK brass cept the small primer in the 308.

Big difference in the 308 and a straight wall pistol case. Even so lot to lot variations can make a difference in bullet pull and needs to be checked with each new lot, I buy the 357 revolver brass in 1000 piece lots. Read the chrono results I posted above and examine the differences between virgin brass and sized/fired brass, crimped or not.

Across 5 different tests there was 18 fps variation in velocity between all 5 tests, 4 fps variation in extreme spread and 1 fps variation in standard deviation. That's for 50 shots over the chrono with 5 different loading conditions.

Check the average velocities between un-sized virgin brass and fired sized brass. Does bullet pull effect burn rate & pressure, if you believe it does (I do) how much variation could there be in bulet pull between virgin un-sized fired brass, test 5 and the other tests?

Can't even imagine how much more consistent than that anyone would want it. But as I said, tests like this are to give the grey matter something to chew on.

Rick

Doby45
10-17-2010, 10:01 AM
The brass I try to use exclusively is starline. I buy a lot of NEW brass, and haven't had any issues just loading it and going (This is for a 454 casull and 458 SOCOM).

THERE is your inconsistancy.. You are using new brass unsized and just loading it. Of course it will be different from your fired brass, because your fired brass has been sized. It would and could be different even if you only shot 20 rounds of the new unsized brass. As much as we would like to think that the factory is going to send us 100% perfectly sized and ready brass, that simply is not the case. What you have done is your failed to remove one of the main variables in your reloading practice and then simply overlooked it as a possible cause for differences in your loads. Even brand spankin new brass get treated the same as once fired brass in my house. Full length size, trim, chamfer, clean and so forth. If the new stuff requires "less" prep then that is fine but that does not mean it requires none.