Consistency applied.

[MBTcustom]

What is the payback for us 'average' rock buster shooters other than bragging rights at the range.

Absoluty nothing. Just remember to keep your rocks large and close.
Personally, I use a hammer for such activities.

. Riflemanship and marksmanship to me means cutting small groups in paper and demonstrating it on demand. This allows me to shoot smaller rocks further away if I ever develop a taste for them, or feel they are threatening me in some way.
More importantly, any skill I have must be honed in order to be maintained. I got to a place a long time ago where I was no longer progressing in the casting department. I didn't think there was a way to get better or to progress till I started using these bell curves to see what I could not normally detect. It works very well, and I am still making progress! Every tme I cast, I learn more, find better methods, or refine the methods I already developed. That's what it's all about for me. I want to either get better or quit, and I don't quit.
I'm either pushing for what I want, or I walk away completely for a while till I can come back to it with fresh perspective.
This system keeps it fresh and sharp for me, and while it does find bad bullets, the point is, it helps me never to make them in the first place. I do not focus on how to cover up or cull my failures. I focus on how to make myself more successful.
Of course, the easy path is to lower my standards and refuse to look too close at what I make. That way, I'll always feel awesome about what I do, but that's just not something I am capable of doing.

[Love Life]

I got a whole bunch of milk jugs I can fill up with water for ya!

[Larry Gibson]

Well I'll continue to mention RPM whether some want to hear about it or not. To not understand and thus to ignore (just because you don't want to hear about it) how RPM and centrifugal force affects a bullet in flight is about as sensible as ignoring the effect of gravity or the effect of the wind on the bullet in flight. Just because you don't want to hear about any of them does not negate their existence and the affect they have on a bullet in flight. Oh sure, you can ignore them alright and have lot's of fun "busting rocks" if that's what you want.

In the example I posted above the RPM at 2892 fps in the 16" twist was 130,140. Since centrifugal force is a product of RPM the same centrifugal force occurs from a 10" twist barrel at the same RPM at 1807 fps. Thus the dispersion would be the same had the same bullet/loads been fired in the 10" twist. However, an additional factor arises with the lower velocity; time of flight to the target at 100 yards. The time of flight was considerably less at 2892 fps than at 1807 fps and the group dispersion is what you see. Given the longer time of flight with the 1807 fps 10" twist the centrifugal force would have longer to act upon and cause greater dispersion.

Whether or not weight sorting is at all worth it is simply a matter of choice; if your happy with rock busting, throw dirt on the rock accuracy then all's well and fine. However some of us are seeking a bit better than "rock busting" close range accuracy as such. We find bullet sorting and weight sorting to be quite beneficial especially when shooting at longer ranges. Consistency in casting a goodsteel states is and excellent method of cutting down the number of bullets that get "sorted out" thus increasing our production of the quality of bullet necessary for our accuracy objective. I believe reducing the number of "culls" (however you sort them out) obtained through consistency in casting is the primary objective of this thread(?).

Larry Gibson

[MBTcustom]

Popper, if you don't mind me asking, how long have you been casting bullets?

[bdecker9]

I'm just a country bumpkin, but I thought that the spin on the bullet was to correct for inconsistencies present in all projectiles. Would think more spin would cancel out more. Want to say more but I'm at work and this li'l phone kb is irritating at best

[largom]

This is an extremely interesting thread, especially some of the replies. I have weight sorted my cast boolits from the beginning, a long time ago. Why? Because it is a way to measure the results of something I made. I weigh everything, boolits, cases, powder and my scale check weights.
I make bell curves with my boolits then I inspect the boolits that are out of the center loop. I inspect the boolits to see if I did something wrong when I made them,if so I want to correct ME. This is what Goodsteel is trying to tell us. The bell curve will show the mistakes. It is up to the caster to determine what must be done to correct them.
Is all of this weighing and sorting to +- .1 grain necessary? NO, not for rock blasting or close range hunting. So why do it? My satisfaction is that I want something I made to be the very best. I want mine to be better than those made by the factories. I want mine to be better than yours. Mine has MY name on it. Are mine perfect? No, but I am still learning.

Larry

[MBTcustom]

Popper, I've been casting since 1994, and everything you are saying makes sense, and is things I have tried. There was a time when just getting a clean base was the challenge for me, and I would have laughed at someone showing a bell curve made of bullets.
The thing is, this is all connected. A perfect bell curve is a goal like a tree on a distant hill to keep you heading for perfection in all ways.

This does work. It can be used by an advanced caster to up his game at the casting bench, but it can also be used by someone with limited experience to help them get to advanced casting proficiency at a startling rate of speed.
Take sgt.mike for example. He has been casting only two years, one of which has been spent using this method, and I can barely tell the difference between his bullets and mine on target!!! That's astounding! Two years after I started, I was just trying to keep my bullets from being too frosty. Had I known about this method then, there's no telling where I would be now, 20 years later!
I thought maybe, just maybe there are some people like me on this forum who would like to get on the fast track to casting success, so I demonstrated how to do it.

Now concerning the mold thermometer:
A: it only costs $32 and
B: it's a help, and one more point of feedback (I think we need all the help we can get) but it's not vital to improvement especially at the place you are at.

You have a PID and a hotplate, which is plenty for where you are at now if you want to use those tools to help you progress in your skill. Once you get to where you can drop bullets perfectly filled out with flat bases, even color, and dropping within a weight range of .7 grains, the thermometer can help you fillet off another .5 grains so that you can turn your bell curves into racing stripes.

[Sticky]

This does work. It can be used by an advanced caster to up his game at the casting bench, but it can also be used by someone with limited experience to help them get to advanced casting proficiency at a startling rate of speed.

Once you get to where you can drop bullets perfectly filled out with flat bases, even color, and dropping within a weight range of .7 grains, the thermometer can help you fillet off another .5 grains so that you can turn your bell curves into racing stripes.

This is where I am.. a newb, trying to learn and refine my techniques to produce largely keepers by normal standards. This thread has already helped me narrow my variations somewhat, still implementing new process control steps as I go (a step at a time til I think I have a handle on that step) and hoping to continue to narrow my range of cast weights til I cull very few. Thankfully, it's easy to recycle these bad'ns and move on.. lol

Thanks Tim and all who are contributing. It does help some of us immensely!

[MBTcustom]

OK, cast at 700 culled
142.9 3
.7 10
.6 29
.4 12
.3 7
.1 1

Culled were mostly divit in base drive band, rounded base or both, about 30% total.
Culls at 680 were rounded base, a couple of the divits, ~5% total. Weight spread was larger.

Popper, what alloy are you rolling with?

[MBTcustom]

Aha, Heinz 57.
Brutal.
Do you have any COWW lead and some solder?

[Larry Gibson]

I'm just a country bumpkin, but I thought that the spin on the bullet was to correct for inconsistencies present in all projectiles. Would think more spin would cancel out more. Want to say more but I'm at work and this li'l phone kb is irritating at best

No, the spin of the bullet is to stabilize the bullet in flight so it travels point forward.

Consider 30-06 milsurp M2 with a 150 gr FMJ at 2700 fps in a match rifle with a 10" twist and a very good scope. The bullets travel point forward and leave nice round holes in the target at 100 yards. Yet the group (5 - 10 shots) sizes run 2.5 - 3.5"+. Now pull some of the 150 FMJs and load a much better made (better as in better balanced) 150 gr Sierra MK over the same cases, powder and primers as used in the M2 ammunition. You will probably get less than moa accuracy - 1.5 moa with that better balanced bullet.

The same principal applies to cast bullets.

APPLIEDBALLISTICS FOR LONG-RANGE SHOOTING, 2^nd edition by Bryan Litz

Page8; “precision is how tightly the shots are grouped together”.

Page144: “The relationship between stability and precision is probably where thebulk of stability misconceptions exist.Gyroscopic stability can affect precision in two ways. First, if thebullet is not adequately stabilized, it will emerge from the muzzle and flywith some significant amount of yaw until it stabilizes (goes to sleep).This situation is bad for precision and addssignificantly to the bullets drag.Thisproblem can be solved simply by insuring the bullet is fired with sufficientstability by choosing a proper twist rate”.

Page147: “2.Bullets that are properlystabilized will go to sleep quickly,without affecting flight performance (BC).If launched with adequate gyroscopic stability, they will fly with nearzero pitching and yawing motion”

[The above are where measuring the TOF andBC of the bullet in actual tests tells us with what twist is best for aparticular bullet.Affected stability isshown by a slower TOF and smaller BC because the drag is greater on the bulletthat has the greater yaw and pitch or which takes longer to go to sleep.]

“It’salso possible for precision to be compromised if the bullet is spinning fasterthan it has to be for adequate stability. [over stabilized in commonverbiage]When the bullet emerges fromthe muzzle of a rifle, it’s spinning very fast. Any imperfections in the shape,balance, or alignment of the bullet will cause it to disperse away from thebore line when it exits from the muzzle. The amount of dispersion is related tohow severe the imperfections in the bullet are, and how fast the bullet isspinning.Higher spin rates produce moredispersion. The situation can create the illusion that the bullet \’sdispersion is caused by excessivestability, but that’s not the reality.The actual stability level of the bullet isnot what causes the dispersion!Theimperfections in the bullet cause dispersion, and the dispersion is isincreased the faster the bullet is spinning. The more balanced the bullets are,the less dispersion will result from spinning them faster.One of the reasons why short range Benchrestshooters choose to shoot short, blunt, flat based bullets [sounds an awful lotlike a cast bullet] is because they require such a slow twist rate tostabilize.The slower twist barrelsaggravate the imperfections of the bullets much less than faster twist barrels,and smaller groups result.”

Page146 under “Conclusions”:“In general, improved precision can beexpected from slower twist barrels (as long as the twist produces satisfactorySg [gyroscopic stability]) because the slower twist barrels don’t exaggeratethe components of dispersion that are cause by imperfections in the bullet.”

As we see the "spin" of a bullet is what cause the dispersion of bullets.

Larry Gibson

[bdecker9]

Thanks Larry. I've been thinking about that since 415 am. I knew of over stabilization , and thought of this. I've been thinking about drive shafts spinning, and when there's a problem you slow down or speed up and can feel it. And of out of balance tires. Like you go 50 -60 mph and they wobble but above and below that speed is hunky dory, and trying to think of how to relate it to this. And just as I read "point forward" I remembered more of why Greenhill was doing his research in the 1st place.

This is definitely a great thread. I have learned a few simple things that, prior to reading, had me scratching my head.

Sent from a keyboard the size of a 50© coin

[MBTcustom]

Isotope core lead is supposed to be 96/1/3
Hardball alloy is 92/2/6
(that's lead/tin/antimony respectively.)

This quote from Laser cast bullets:

The inclusion of silver in conjunction with our proprietary blend of 7 other virgin elements produces an unbeatable bullet of unprecedented toughness, consistency and precision.

I'm confused. What were you trying to achieve again?
I mean what was your target alloy?

Also, why add copper? It has been proven that standard COWW + 2% tin can be pushed to 2500fps with superb accuracy from a barrel of the correct twist rate.
Seems like a lot of money and work to get an alloy that you cannot reproduce to achieve a goal that is easily met by alloy that can be easily obtained for a fraction of the cost of the firearm you are shooting the bullets out of.

Concerning your copper enhanced alloy, I shelved the idea for the time being because although it makes a very tough bullet, I found shrinkage and mold fill out to be a problem that needs addressing by heat or some other means.
Looks like you're finding out the same thing.

[MBTcustom]

its a good thing you chose a short bullet for this effort.
But back to your 8 element, copper enhanced, silver infused alloy:
You're having issues casting with it.
This meathod as I have described it will help you determine what is working and what isn't.
I suggest you cast 100 bullets, arrange them as described in a bell curve (I would actually recommend you seting them nose down so you can see the bases).
Observe, change one thing and repeat.
Dial in your ideal alloy temperature first, then mess with your timing till you get where you want to be.
Changing two of more things or failing to observe your progress is a recipe for spending a decade learning what you could learn in one afternoon of testing.

Also, not to bust your bubble, but I wouldn't get my hopes up about shooting sub MOA out to 200 yards or further unless you have a very long barrel on your AR. You're at the ragged edge of the RPMTH there at 144,000 RPM, and that short barrel and your gas system is going to make things even more challenging. I'd say you're in for a difficult time getting consistent and dependable linear dispersion from that setup.
However, this further underscores the need for absolute process control at your casting/loading bench, as well as careful note keeping.

[MBTcustom]

Oh, COWW usually has a bunch of stuff besides the Pb,Sb,Sn in it.

As one who has done more XRF testing of COWW alloy than anyone on this forum, I can corroborate your statement, and also add that the total percentage of impurities rarely exceeds .2% (not enough to make much of a difference at all.
The way the alloy responds to heat and quench is also very consistent as long as you smelt in large batches of 100lb or so (I usually go 150lb batches).
Individual COWWs vary in composition somewhat, but taking a pot full of 150lb of them and analizing it has proven to be remarkably predictable: 2.33% antimony, less than .5% tin, and less than .2% whatever that hemisphere of the periodic table contains (for the record, I have yet to find much trace of arsenic at all).
I have found that if I reassign my calculator values for COWW to 2.33% antimony, 0% tin, and 97.67% lead, I can hit my target alloy exactly every time when smelting with other alloys of known content.

Basically: Yes, there are impurities and trace of as many as ten metals in COWW, and it is so minute it doesn't amount to a hill of beans.

However, intentionally spiking the alloy with significant amounts of copper, silver, and who knows what else, is going to have a very real and measurable effect on bullet quality. One of the worst effects that copper contaminated alloy exhibits is bullets that are not straight. This is easily seen by putting the bullets in a precision collet lathe and measuring their TIR.
What I see is bullets that are about as straight as bananas (ie: you're shooting with bent arrows) coupled with bad fill-out, and the bullets come out undersized.
(For what it's worth, I also measure my target bullets in this way cast of "excellent alloys" as described in the OP, and I will always find 2 or three out of 100 that are warped. I do not know what causes this, and the bell curves can not tell me anything about it either. This is one test that I certainly do use to cull bullets with, simply because I have no idea of how to prevent it in the first place)

So if you don't play your cards right, whatever you gain in bullet toughness, you will lose in bullet quality (and then some). This compromise only works if you maximize your bullet quality to the point that you can realize the positive effects of the toughness and give up as little as possible in the consistent accuracy department.
In that regard, I would refer you back to the OP on this thread as it will help you find the best place to run with that alloy where you can realize the best effect. I don't think you're ever going to get racing stripe bell curves with that alloy, but you can definitely find the best process to make your bullets as excellent as possible.

[Love Life]

This thread does a great job of showing both the art & science of bullet casting.

[Larry Gibson]

Most of us these days use an electronic scale to weight sort cast bullets. Electronic scales by necessity have a +/- accuracy range. I have tried several over the past years and have settled on the Hornady GS-1500 for my own use. It comes with a 100g calibration weight and is easy to use. Anytime the scale reads other than 0.00 when the bullet is taken off I recalibrate. That gives me as good as consistency as I've gotten and is better than with any other scale.

Another consideration for "consistency" is just how "consistent" is your electronic scale and that begs the question. I just completed weight sorting 531 linotype 30 XCBs. The GS-1500 has a "resolution" of .1 gr which I've come to realize is close to a .075 gr +/-. Where the acceptable range begins and ends is dependent on the median weight selected. Using a tried and true Redding balance scale which is zeroed and calibrated with certified weights on which I can read to .05 gr I decided to test 20 selected bullets from the batch just weight sorted. I randomly picked 20 out of the batch the GS-1500 said weighed 154.1 gr and weighed them on the Redding scale. The results were;

154 gr (8)

154.05 gr (4)

154.1 gr (4)

154.15 gr (4)

As we see the GS-1500 did weigh them with a +/- .075. However the actual mean was closer to 154.075 than the 154.1 gr the Hornady GS-1500 weighed them at. Given that excellent level of consistency I doubt I'll fault the GS-1500!

Larry Gibson

[Larry Gibson]

popper

I guess if all you shoot is 50 yards then you're doing as good "consistently" as you want. It's really counter productive to try to determine accuracy for longer range shooting based on such short range testing. Dispersion is a function of range, especially with imbalanced and inconsistent bullets. Shooting at such short range demonstrates little other than you have an effective short range load. To claim accuracy (group size/dispersion) at longer range is unrealistic. As an example here is a test at 50, 100 and 200 yards with a load that was over the RPM Threshold demonstrating non linear group dispersion;

Attachment 134137Attachment 134139

Here is the same bullet in the same rifle loaded under the RPM Threshold. Note the linear group dispersion to 200 yards;

Attachment 134141

Note the 4.25" group at 200 yards where we paid attention to consistency and kept the RPM under the RPM Threshold. That's a lot better where even with consistently cast bullets when we crossed the RPM Threshold the group size/dispersion increased to 14.5". Note with the 50 yard groups with either; both are quite satisfactory for a lot of close range shooting. However, only one of them is truly useful for longer range accurate shooting.

The difference between the two is why we do what we do to be consistent and to control the RPM.

Larry Gibson

[MBTcustom]

Most of us these days use an electronic scale to weight sort cast bullets. Electronic scales by necessity have a +/- accuracy range. I have tried several over the past years and have settled on the Hornady GS-1500 for my own use. It comes with a 100g calibration weight and is easy to use. Anytime the scale reads other than 0.00 when the bullet is taken off I recalibrate. That gives me as good as consistency as I've gotten and is better than with any other scale.

Another consideration for "consistency" is just how "consistent" is your electronic scale and that begs the question. I just completed weight sorting 531 linotype 30 XCBs. The GS-1500 has a "resolution" of .1 gr which I've come to realize is close to a .075 gr +/-. Where the acceptable range begins and ends is dependent on the median weight selected. Using a tried and true Redding balance scale which is zeroed and calibrated with certified weights on which I can read to .05 gr I decided to test 20 selected bullets from the batch just weight sorted. I randomly picked 20 out of the batch the GS-1500 said weighed 154.1 gr and weighed them on the Redding scale. The results were;

154 gr (8)

154.05 gr (4)

154.1 gr (4)

154.15 gr (4)

As we see the GS-1500 did weigh them with a +/- .075. However the actual mean was closer to 154.075 than the 154.1 gr the Hornady GS-1500 weighed them at. Given that excellent level of consistency I doubt I'll fault the GS-1500!

Larry Gibson

Great post Larry.
I use a cheap Frankford Arsenal digital scale. It is touted as having an accuracy of .1 grains (which I had to see to believe). After testing with standards, I found the accuracy of the scale is actually slightly better than +-.1 grains ie: definitely within .2 grains of indicated weight (amazingly accurate for what I paid for it).
It is sensitive to temperature, but I only run my bell curves when the shop temperature is levelized.

I agree completely with your statements above. Even with jacketed bullets, linear dispersion is never to be a forgone conclusion. I have made shots on game at distances longer than what I had tested, but I had a very good load with my 300 Win Mag that demonstrated linear dispersion from 50 to 100 to 150 to 200 yards (at 200 the group size was 1.5" and that is the limit of the local shooting range) and I felt on shaky ground taking a shot at 300 yards with that rifle and load.

It is much worse with cast bullets because non linear dispersion is very very common, and in fact, I assume that the bullets will go wild at distances past where I have tested them at, and I find I am correct in this assumption much more often than I am to the contrary.

Accuracy at distance with cast lead is pure skill with the pot, press and trigger, along with a very shrewd selection of components used for the task.

[Doc Highwall]

Here are two links to help you with your electronic scales and preventing them from drifting.

http://bulletin.accurateshooter.com/...-static-spray/

http://bulletin.accurateshooter.com/...rift-problems/