banana cases are no good

[marksman]

because of the cold wet days we are having in Sicktoria at the moment in ISO l've been doing a bit of case prep
one thing l am doing that l thought may be of interest to some is checking the case wall thickness symmetry

l haven't yet found a brand of brass that has perfect case wall thickness uniformity although some are better than others

when fired asymmetric cases usually bend, the thinner side of the case will stretch more than the thicker side, the result is what we call a banana
FLSing will not remove the bend, so the case neck will not line up with the case axis and when the loaded round is chambered the bullet will not line up with the bore axis. bullets that dont align with the bore axis will deform asymmetricaly destroying bullet balance, accuracy is not good





the idea of bent cases or banana's has been around a long time, david tubb talks about it in his sierra reloading video and Creighton Audette mentions it



when doing this is you would cull the really badly asymmetric cases, l'm pretty harsh on some cases, then you can segregate them making an index mark on others at the thick or thin part of the case so you can put the case in the chamber the same way each time giving your shot a better chance at shooting the same as the last, what you are after, repeatability

here are photo's of a case before and after that some would say is ok when index marked but l wont use it if it has over 1.5 thou difference





this is of course only one thing that has an impact on precision and unexplained flyers and we all hate flyers but if you want to have better results at longer ranges is IMHO something to think about, if your serious its not for everyone

[SCJ429]

What brand of brass are you seeing that in MM? You don't see that in some better brands. I had a mate who could turn perfectly straight brass into a banana with his roughneck sizing.

[TassieTiger]

Geezus...something else to now worry about lol.
Forgive the silly question. Even if the projectile was not square on into the lands, wouldn’t the centrifical forces and the barrel itself - sort out concentricity (centralising) by the time the projectile exits ?

[marksman]

that case is a once fired norma 308 win, out of 50 there were 8 over the 1.5 thou that have been put aside SCJ no brand is perfect



TT" all bullets deform when engaging the rifling sealing the bullet in the bore, bullets that are misaligned with the bore are likely to deform asymmetrically destroying the bullet balance so the bullet will not have as much potential to be accurate after it is out of the bore, at 100y you may not really notice much, the reason why testing should be done at longer ranges, IMHO really precise shooting rifles should be tested at 300y
once indexed the groups shot will be better and tighter without unexplained flyers, l dont do this as l keep them under 1.5 thou so l dont need to, there will be fudge
the old way of sorting the cases was to put aside cases when the bullet was an unexplained flyer if all other QC was at standard

my neco concentricity, wall thickness and runout gauge manual suggests that between 0.0000" to 0.0015" difference is excellent and match grade, between 0.0015" to 0.0030" are good if indexed for a reasonable standard, anything more is ok if indexed to a point of expectation

what you can get out of this is that if you are having problems with flyers your cases may be the cause of it
its definitely not for everyone but it if your interested in longer range it should be considered

[on_one_wheel]

Another reason I love using the good old Lee Loader.
Cocentricty, the projectile is held true by the die and the seating rod is also held true while it seats the projectile.

Handloaders, weep at my inexpensive yet highly accurate means of smashing rounds together using little more than a spoon and a hammer

715WOs9NcAL._AC_SX425_.jpg (39.87 KiB) Viewed 3450 times

[Oldbloke]

"neco concentricity, wall thickness and runout gauge manual suggests that between 0.0000" to 0.0015" difference is excellent and match grade, between 0.0015" to 0.0030" are good if indexed for a reasonable standard, anything more is ok if indexed to a point of expectation"

Interesting discussion MM. I have heard of this but no knowledge.
I have a dial indicator, so will see what I can gerry rig.
I'll head out to the man cave and check a few of my reloads. 0.0015" inch is certainly a high standard. Will kill some time.

[Blr243]

Does neck turning correct these bananas?

[marksman]

Does neck turning correct these bananas?

nope, nothing can fix the banana but that's a good way to see if you will have a very thick side to the case,
if one side of the neck is much thicker than the other it will be the same all the way down

what neck turning will correct is getting your neck axis centerline in line with your case axis centerline
and why if you dont neck turn you should use the lee collet die for neck sizing because it sizes off the mandrel from the inside of the neck keeping the inside neck inline with the case axis centerline

[marksman]

Another reason I love using the good old Lee Loader.
Cocentricty, the projectile is held true by the die and the seating rod is also held true while it seats the projectile.

Handloaders, weep at my inexpensive yet highly accurate means of smashing rounds together using little more than a spoon and a hammer

715WOs9NcAL._AC_SX425_.jpg

this isn't the answer to fix the banana cases but l agree with you that inline dies such as these are very good and better than a lot of press dies out there
your idea that they promote good concentricity is IMO right

[marksman]

"neco concentricity, wall thickness and runout gauge manual suggests that between 0.0000" to 0.0015" difference is excellent and match grade, between 0.0015" to 0.0030" are good if indexed for a reasonable standard, anything more is ok if indexed to a point of expectation"

Interesting discussion MM. I have heard of this but no knowledge.
I have a dial indicator, so will see what I can gerry rig.
I'll head out to the man cave and check a few of my reloads. 0.0015" inch is certainly a high standard. Will kill some time.

it would be interesting to see your gerry rig OB, post a photo and show us how it works when you can

[Oldbloke]

Not sure what I can do yet. The gerry rig might become my next covid project. Lol Just to get an idea if my ammo is bad.

I'm not unhappy with the ammo. Getting ok hunting accuracy. Just under moa which serves my purpose.

And now I better understand what you said about using a FLS die to neck size not being very good. (Longtime ago)

[Blr243]

Tis quite a deep subject

[marksman]

Tis quite a deep subject

it certainly is, and why the biggest majority of reloaders wont do it
but if you can get everything in line your will have a better probability for your rifle to be shooting straight
when l say everything l am talking about how the rifle is put together as well as your loaded ammo
its like building a house, "start straight and finish straight", or how straight can you hammer a crooked nail

if you are happy with .5 moa @ 100y and only shoot 200-300y you can get away with good enough
believe me when l say .5 moa is good enough in my books but l have found doing a little extra once in the cases lifetime will give better results
my cases last a long time, l do not sit around doing this type of thing all the time and l spend a hell of a lot more time shooting for the freezer
mine, plenty of other people and bones for the dogs no one misses out

[Oldbloke]

So, I tried two things.

Method 1.
A surface plate set up on a slight angle.
Using my finger I controlled the speed the case rolled down the slope.
Focusing on the light (desk lamp) shining between the bullet and plate I thought I would see an obvious variation. I think
you would only see variations of 0.010" or more. So of pretty limited use.
I reckon you could also use a piece of glass painted black to do this.

Method 2.
Rolling case on a small V block with a "pointer" very close to the bullet.
I could see 2 bullets that had some run out. TBO just a guess about 0.005"

I have put the dodgy 223 aside. I should have put the 3006 aside. Bugger. But it should show up when I complete my DIY Version.

Results

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If I'm right with the 0.005" run out I'm not unhappy with the results. But I have no idea what 0.005" run out would result in at the target. MM??

Method 3. DIY
I have an old imperial mitutoyo dial gauge. (No obvious way to mount it today.) It still works OK. I have an idea for a DIY using the dial gauge that I think
will give much better results. Not hugely different to a few designs I saw on youtube. But I need to get a plate of steel to use as a base first.

I have also noticed that MMs system seem to amplify the run out due to leverage. Mine will not do that. So it will be inherently less precise. It will be a
KISS system. LOL But easy to make.

MM should I move this to the DIY thread. I don't want to take over your thread?

Method 1.jpg (430.28 KiB) Viewed 3370 times

Method 2.jpg (262.46 KiB) Viewed 3370 times

[Oldbloke]

[quote="on_one_wheel"]Another reason I love using the good old Lee Loader.
Cocentricty, the projectile is held true by the die and the seating rod is also held true while it seats the projectile.

Handloaders, weep at my inexpensive yet highly accurate means of smashing rounds together using little more than a spoon and a hammer

Agree 100% Those old Lee loaders have some good points. Normal dies rely more on the case neck to align the bullet.

[marksman]

you are not taking the thread over OB leave it where it is, if l haven't explained well enough for some to understand it may help

what you are measuring is not what l am, the neco is the only gauge out there that you can measure the case wall thickness with
it uses a chord anvil that with the deflection indicator will show variations in case wall thickness
you are right that the neco will amplify the run out due to leverage but that does not happen if you are not touching the case as in the original photos
the case touches the chord anvil sitting on it with the dial indicator sandwiching the case wall showing the thickness,
you turn the case a 1/4 turn at a time looking for differences when you let the case go, very accurate measuring
l will add a pic to show what is not seen in the original photo's



if when checking runout of the bullet you are having more than 0.0002" your case will have a big probability of being a flyer out of the group, not good
0.0005" is for plinking at best not for small groups, this may not be because of a case problem, it can happen from sizing or seating techniques

IMO to check for asymmetrical case wall thickness without the proper gauge you either check for overly thick necks on one side or after firing before sizing with your case between two v blocks check for wobble in the middle of the case with a dial indicator
or do what the old timers used to do, cull flyer cases out of the group? probably the reason they did not have huge amounts of cases, maybe 20 or so at a time

your methods eg.. rolling a round across a pane of glass is a good one for checking bullet runout because the glass will be super flat, if you paint it you will corrupt the flat surface

[marksman]

Another reason I love using the good old Lee Loader.
Cocentricty, the projectile is held true by the die and the seating rod is also held true while it seats the projectile.

Handloaders, weep at my inexpensive yet highly accurate means of smashing rounds together using little more than a spoon and a hammer

Agree 100% Those old Lee loaders have some good points. Normal dies rely more on the case neck to align the bullet.

you can still get deformed cases from the lee hand loaders,
you are still relying on the neck to align the bullet and they are made to a sammi spec that is sloppy
still a very good die IMHO

l have a couple of wilson hand dies setup with my chamber reamer and bushings,
so a perfect fit to my rifle chamber and the only dies l know l do not ever have to check the loaded rounds with, zero runout
its more expensive when you setup but still cheaper than say redding s type dies

[Oldbloke]

MM. After reading the thread again and the last pic with no case I understand now. Should have read more carefully.

Yes, I agree paint is likely to effect the result. Maybe paint the underside. Lol

I'm not going to get into what your doing, I simply don't have the need. And inclined to think there would be more effective ways for me to improve my ammo. e.g. sorting cases by weight or water capacity.

But I think I'll still make my DIY "bullet run out checker". I can then check them after reloading and put aside any that are not concentric.

Interesting thread.

Trying to source a piece of MS plate now from SILaw.

[marksman]

no worries OB
l said earlier that "this is of course only one thing that has an impact on precision and unexplained flyers", bullet runout, neck tension, internal case volume all come into play and are a big part of QC in reloading your own rounds,
this is not for everyone, only the really serious reloaders with OCD
one thing l would advise in your DIY bullet runout checker is that if you are using factory chambers or sammi spec you may find a bulge, usually do in the lower case in front of the solid web that is normally more to one side and not equal around the case making the case offset that will be affected by v blocks or being laid up on a flat surface, a better idea is the hornady concentricity gauge https://www.youtube.com/watch?v=h7PAeygRZAA
for what it is worth its a reasonable price IMO, l do not like the idea of straightening loaded rounds but the setup for checking runout is brilliant

[Oldbloke]

no worries OB
l said earlier that "this is of course only one thing that has an impact on precision and unexplained flyers", bullet runout, neck tension, internal case volume all come into play and are a big part of QC in reloading your own rounds,
this is not for everyone, only the really serious reloaders with OCD
one thing l would advise in your DIY bullet runout checker is that if you are using factory chambers or sammi spec you may find a bulge, usually do in the lower case in front of the solid web that is normally more to one side and not equal around the case making the case offset that will be affected by v blocks or being laid up on a flat surface, a better idea is the hornady concentricity gauge https://www.youtube.com/watch?v=h7PAeygRZAA
for what it is worth its a reasonable price IMO, l do not like the idea of straightening loaded rounds but the setup for checking runout is brilliant

Yes, thanks, but was aware of that. My idea will avoid that issue. Understand what your saying.

I'm informed the base plate is ready to pick up. Pretty fast service by the SIL. Lol.

The design is basic. But I'm sure it will work reasonably well. Keeping in mind I probably only load about 100 rounds a year.

You really are OCD lol. Obviously knowledgeable in reloading. I usually stick to the basics. Lol Not sucking.