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Slick Pilot
06-30-2008, 04:04 PM
I weighed some of my 30 caliber bullets the other day and found that they seemed to be very consistent, but what do I know?

These bullets are from a Lyman 31041 mold which is designed to throw a 173 grain, gas-checked, bullet.

Mine came out at about 180 grains after applying the gas check and the lube. I weighed 57 of them to get 50 that were 180 grains +/- 1 grain. Most were +/- 0.5 grain.

That seems pretty good, but what is the standard?

I have a friend who has shot some in his match grade M1A, and he says they are very accurate.

Thanks.

docone31
06-30-2008, 04:18 PM
Sounds like good to me.

Echo
06-30-2008, 05:04 PM
I would define that as 'good', but then I'm not a BR shooter. Whatever. +-1 grain would be loaded by me...

ktw
06-30-2008, 05:40 PM
I think a 1-2 grain variation in a rifle bullet of that size is normal, particularly in a multi-cavity mold. I have some DC molds that throw within 1 grain from both cavities and some that throw a 2 or 3 grain difference between the cavitites.

For most bullets I don't consider that to be a big problem.

For rifle bullets, in scoped rifles where I am searching for top accuracy with cast, I tend to weight sort them; throw out all of the fliers and group the rest into batches of plus or minus a half grain.

-ktw

joeb33050
07-01-2008, 06:09 AM
First, every mold I've ever owned with 2 cavities casts bullets of different weights in each cavity. I make a little dent, high and low generally, on the forward end of each mold cavity. Bullets then have "dots" and can be separated by cavity.
Ex: 31141 DC mold, "Bottom Dot" avg = 169.5 gr., "Top Dot" avg. = 168.6 gr.; cast 3/24/08

If bullets are visually inspected, bad set aside, the balance weighed; then the bullets from a cavity will weigh +/- .5 grain for 99.9% of the bullets.
This is based on records of weights of 16,997 cast bullets from 58.5 gr. to 482.1 gr. average weight. The standard deviation averaged .152 grains over all weights and calibers.

I shoot outliers as foulers/sighters, and cannot say that bullets varying in weight +/- .5 to 1 grain shoot any worse than those varying less.

I consider the "standard" to be +/- .5 grains for any lot of cast bullets.

joe b.

Junior1942
07-01-2008, 07:18 AM
>I consider the "standard" to be +/- .5 grains for any lot of cast bullets.

Why not compute the Standard Deviation for the lot of bullets?

See http://www.castbullet.com/shooting/standard.htm

I use 1 Standard Deviation for target work and 2 SD for hunting & plinking.

Bret4207
07-01-2008, 08:11 AM
A half gr in a 45 gr 22 cal boolit is a lot different than a half gr in a 600 gr 45 cal boolit. I have moulds that throw very consistently and some that just don't seem to want to cooperate. Rather than worry about weight of +/- a gr in a 180 boolit, I'd be far more concerned with fill out and base. Even with the gas check the base has to be as perfect as possible. You can still have problems even with near perfect weight too. A mould that always throws boolits with voids may have the weights very close and the voids may still throw them out of the group. You'll never know of course unless you start sectioning boolits.

I guess my advice would be if you have a personal accuracy standard, stick with it. Don't let someone else dictate your decisions. The magazine writers use the "Keyboard Accurizer version 7.9.76849" to get their groups. Your average internet poster....who knows? I ahve a feeling 99% of the incredible groups reported are massaged at least a little. The guy the reports a 2" group is probably being more truthful. You decide what good for you and go from there.

grouch
07-01-2008, 08:14 AM
In 30 cal. bullets, I remelt bullets outside +/- 0.2 gr. If the temperature is right either ww+2% tin or 20 : 1 gives me a 90% retention rate.
No scientific reason for that cut - off, it just seemed reasonable.
Grouch

jonk
07-01-2008, 08:53 AM
While I have been known to sort by weight, unless you are shooting at 300 yards or better I seriously doubt it will much affect things with a proper load. Under 1 grain variance sounds good to me!

Junior1942
07-01-2008, 09:06 AM
A half gr in a 45 gr 22 cal boolit is a lot different than a half gr in a 600 gr 45 cal boolit. . . .Exactly. That's why sorting by SD works so well. 1 SD is always 1 SD.

HeavyMetal
07-01-2008, 09:25 AM
I have, and do, sort by weight for "serious" shooting. Not to keep a specific weight varience but to make sure I don't get one to lite or to heavy.

I've weighed large batch's of 45's and found several that were 6 grains heavier than the norm and one that was 10 grains less than the norm! Strangely the lite boolit was filled out completely and had passed a visual and looked good under a Magnifiying glass as well!

All of them went back in the pot and from then on I sort, group by weight ( + - .05 gr) size and box all boolits in each group seperately.

Echo
07-01-2008, 10:00 AM
All this Standard Deviation stuff gives me a headache, and not for the reason you might think. I taught Stat (and Research Design) at the Community College and University level. U students were pretty good, but, Oh, those CC students. The blank looks got me out of the Stat teaching business...

But what Junior says makes sense. His method will include about 2/3 of those cast for serious work, then include another near third for all other work, throwing back in the pot about 5% of those cast. But it requires more record keeping than what I care to do. If I'm serious, I weigh every boolit, and throw the outliers (a good stat term) back in the pot, segregating the rest into +- .5 gr batches. Works for me...

Piet
07-01-2008, 11:17 AM
The following works (sometimes)
A sample of 25 bullets is weighed and then the mean and standard deviation is calculated.
Everything outside the range Mean - 1xSD / +2xSD is thrown out.
In a perfect (normal distribution) world about 82 % will be in this range.
Voids will cause light bullets therefore the range is biased towards the heavy side.
The sample SD should be about .3 gr.
I was never good at statistics but like I said this seems to work.

joeb33050
07-01-2008, 11:59 AM
A half gr in a 45 gr 22 cal boolit is a lot different than a half gr in a 600 gr 45 cal boolit.

My data shows a suggestion that SD is less than proportional to mean/average bullet weight. So 170 gr SD maybe .15 gr., 410 gr. SD maybe .22 gr. My problem is that I don't cast heavy or light bullets often enough to work it out. No proof yet.
Those castijng light Ex 22 or heavy Ex 45 bullets a lot could solve the question by reporting, say, 30 weights of visually perfect bullets, a few times.

I shoot sets of 25 bullets in 5, five-shot groups. So, here's what I do. 11/20/07, 31141 Top Dot
161.9-1
162.0-9
162.1-55
162.2-46
162.3-14
The 162.1 and 162.2, 55 + 46 = 101, are keepers, to shoot for record. All the others are used as foulers/sighters. The record bullets are closer together than the lot. However, I've never seen it make any difference, foulers shoot tight groups.

joe b.

Bret4207
07-01-2008, 03:51 PM
I'm reminded of the report some years back of the guy who shot a group with his "foulers" that was better than his weighed boolits! A guy that can't see anymore, like me for instance, probably couldn't tell the difference. With a bench gun and all the goodies.....?

selmerfan
07-02-2008, 12:21 AM
Wow, some of you guys are more picky than match grade bullet manufacturers of condom boolits! 1 grain deviation is good enough for me, but I don't shoot at matches, just oil bottles and milk jugs, but I cans till get a 1 1/2" group at 100 yds.
Selmerfan
PS - And I'm new at this casting thing :)

454PB
07-02-2008, 12:30 AM
I used to spend hours weighing and segregating cast boolits, then comparing the results to nothing more than a visual examination. I found no difference.

Lumpie
07-02-2008, 01:37 AM
I have been loading, and casting for about 55 years. I normally don't express my opinion on these aforementioned items. But here goes! When I was about 8 years old, I would hang out with my Father, and Grandfather, on cold days. I would watch them cast bullets. I guess , I was just like anyother 8 year old. Asked more questions than I should have. The things that I remember the most was they would say you can't make a sows ear into a silk purse. You start out with the best metal you can get. The best moulds you can get, and the finished product, has a better chance of being of the nature you would expect. The best metal I have found is 1 part highspeed Nickel Babbit, and 9 parts pure lead. I have shot 30 cal rifles with cast bullets, all of my life. I still use the mould that belonged to my father. It is a 8 cavity Ideal Armory mould. It was designed by the U.S. Government to shoot in 03 Springfields, and P17 Enfields. These were employed at National Guard Armories. The would allow troops to shoot many many rounds for a fraction of the cost of Jacket ammo.These moulds were made with a caster in mind. The bullets come from the mould at .3115. They will weigh out about 191 grs. I took up shooting the 1911 Colt, when I was in the Army. The mould I have always had good luck with is the Hensley & Gibbs #68PB 8 cav. I use the H&G 130 bb for my hard ball shoots. It is a 8 Cav. Some years back I took up shooting 45 Cal rifles. Mostly Highwalls. I use a H&G 399-4 6 cavity. Now I have shot rifles with people that spent more time trying to figure out the ropes, so to speak, than the time they spent smelling the Roses. Now having said all of this, does not make me an expert at anything. I just find that what works good, is what we are all after. Lumpie

joeb33050
07-02-2008, 05:02 AM
I used to spend hours weighing and segregating cast boolits, then comparing the results to nothing more than a visual examination. I found no difference.

The main reason that I weigh cast bullets is to find and re-melt the odd outlier that looks visually perfect and is maybe 1.5-4 grains less weight than the average. These DO shoot out of the group, and will screw up a whole 25 shot test.
Hi, Lumpie!
joe b.

Bass Ackward
07-02-2008, 07:16 AM
I weighed some of my 30 caliber bullets the other day and found that they seemed to be very consistent, but what do I know?

These bullets are from a Lyman 31041 mold which is designed to throw a 173 grain, gas-checked, bullet.

Mine came out at about 180 grains after applying the gas check and the lube. I weighed 57 of them to get 50 that were 180 grains +/- 1 grain. Most were +/- 0.5 grain.

That seems pretty good, but what is the standard?

I have a friend who has shot some in his match grade M1A, and he says they are very accurate.

Thanks.


Slick,

This is pretty simple really and it escapes soooooo many people.

The standard is what happens on paper. What happens on paper depends on what YOU do to it.

The vast majority of molds are base pour. Air rises and tends to get trapped in the base area. Air is weaker than lead.

This in itself has zero to do with short range accuracy. Short range being defined as a range where you have enough forward velocity to stabilize it, that it doesn't become .... unstable.
Where it does have a factor is how you choose to launch it. The secret to shooting cast is solving the problems that WE create.

The base is the steering wheel of the bullet. So if the pocket crush fills, you lose the square base, and you have just lost accuracy. A solid lead bullet, and harder lead bullet are therefore stronger and ultimately subject to more of our abuse.

1. If you shoot faster powders or smaller case capacities per bore diameter, then you need a stronger base and a harder bullet. If you shoot ultra fast powders, you better mold real good bullets. Inertia will work against you meaning the more bullet weight you choose to shoot in a bore diameter, the earlier up the pressure scale and the worse fliers become.

2. If you generate velocity with slower powders and larger case capacities, you will notice less effect because the base may remain undisturbed. I have shot bullets with 5 grains of difference in weight in 35 Whelen and still held 1 1/2" groups at 100 yards using slow powders. I mean these things were visual nightmares.

So how cheap you want to shoot them along with the mental thought processes you use to determine a logical powder selection, will set the requirement for your cast bullets that you must adhere to. Both for weight and hardness. These will determine what you read as to standards.

All of this because .... the base is the steering wheel of the bullet.

45 2.1
07-02-2008, 08:16 AM
Good is what does good, irregardless of all the effort put into something that is veritibly perfect that doesn't do good. Its what you put in the gun that makes or breaks results. A boolit that actually fits the gun is much, much better than one that doesn't. All boolits are not equal in design either, many are meant for a specific use. Get the right alloy, lube, and components and you'll do better than any number crunching says you should be able to do.

runfiverun
07-02-2008, 04:47 PM
i find that when i cast them has an affect on what they weigh also.
i have taken to casting my rifle stuff on high humidity days,or i create an high humidity
situation, with an evaporative cooler.
all of my rifle boolits weigh an average of 1 grain heavier when done under these conditions.
but i just load and shoot them if they weigh within 1 gr of each other.
and this is how i sort them.
everything 146.0 to 147.0 goes in the main cup.
anything over in another [ had 20 out of last 1500]
and anything under in another [had 12 of these in last 1500]
i guess i could sub-sort ,but is it going to cut me down from 1" to 1/2" ?? doubt it.....