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View Full Version : Bullet Quality....and how much do we need?



BruceB
09-15-2007, 03:14 PM
This is a spin-off from the interesting "Molds and Heat" thread, where every conceivable factor is being considered for its effects on the final product...the cast bullet. It gets very complicated, believe me.

Being a simple-minded soul, and having cultivated a "method" which gives me beaucoup boolits in very short order, I decided to post a few stats on two of my recent production runs.

ALL THE BULLETS IN THIS EXAMINATION WERE UN-INSPECTED.

On last Thursday, I cast about six hundred Lyman 311466 from a two-cavity mould. The Loverin designs like this one are considered a bit tougher to cast without flaws due to their multitude of small bands and grooves. Alloy was straight wheelweights, temperature was my RCBS-pot-maximum normal 870 degrees, and the production rate (measured over the last fifteen minutes of the session, when any fatigue after several hours' casting would be most evident), was 540 bullets per hour.

I measured ten of those 311466s a few minutes ago. ALL had basebands at .310", and ALL had the fattest part of their short noses at .302".

Weighing 61 of these 311466 bullets into half-grain batches (155.0-155.4, 155.5-155.9, and 156.0-156.5) I found 15 bullets in the 155.5-155.9 batch, 43 bullets in the 156.0-156.5 batch, and just three in the 156.5+ bunch. These three all showed the little "wires" created when the mould is filling so wonderfully-well that even the vent lines are taking some alloy...I love to see that. The wires, of course, were the cause of the slightly-heavier weight.

The second sample came from a June '07 casting run of 311291, one of our crew's all-time favorites. As you read the variations below, consider that these bullets came from a FOUR-CAVITY MOULD, repeat: FOUR different cavities. Measurements for both these and the 466s above were done with a Mitutoyo electronic caliper, good only to a half-thousandth, which is sufficient for my purposes.

311291 ten-bullet sample, nose diameters: all but two measured .301", and the other two were at .3005".

311291 ten-bullet sample, baseband diameters: seven measured .312" and three were .311".

Grabbing a big handful of bullets from the bin, I came up with exactly 85. The weight classes were established as 175.5-175.9, 176.0-176.4, and 176.5-176.9.

40 bullets fell into the 175.5-175.9 range, 35 bullets into the 176.0-176.4 range, and ten into 176.5-176.9 class. Again, the ten heaviest showed the 'wires". I can state that the vast majority of the two larger groups will fall into a half-grain spread from 175.7 to 176.3 grains.

So...casting hot at 870 degrees, casting fast at over 500 per hour with the 2-cav and probably at least 800 per hour with the four-cavity, with NO FLUXING, adding metal to the pot frequently without stopping the casting, water-cooling the sprue and plate, I still come up with extremely small dimensional and weight variations. For my purposes, and for those of most of us here, I believe, maximum weight spreads of one grain and diameter spreads under a thousandth are amply good.

This is not to be interpreted as throwing rocks at the more-scientific among us! I post this so that perhaps a newcomer won't be so overwhelmed with the complexities being discussed, that he becomes discouraged without ever trying this hobby. Plus, of course, I don't mind bragging JUST a teensy little bit....

44man
09-15-2007, 04:15 PM
I can accept your bragging Bruce. It all boils down to experience. A smooth rythm and being relaxed while casting. No lost motion or big mess. Turn on the music and ignore the little things that don't mean anything in the end.
I quit weighing long ago and a cosmetic inspection is all thats needed.
Good job! :drinks:

454PB
09-15-2007, 04:26 PM
Yeah, Bruce, I get into some of the more technical discussions. I usually just report what I've seen, learned, proved and disproved.

I've been the "weigh every boolit" routine, and found it to be a waste of time. I give them a quick visual inspection after they hit the towel, and return the hot rejects to the pot (which is a no-no to some purests), and a thorough inspection before sizing lubing. I use a bottom draw pot 98% of the time, flux well before casting, and leave the dross on the surface as an oxygen barrier. I don't flux again until refilling the pot. I've done all the things that I read were required while learning to cast 36 years ago, and discarded all the ones that I found were not needed....like fluxing every 15 minutes.

I don't consider myself a bench rester and I don't compete, so my personal group sizes and consistencies are my criterion for well cast boolits.

kodiak1
09-15-2007, 07:33 PM
Bruce I like your post. As 44man stated experience and environment when casting makes a big difference on quality.
If you were dumping them at over 500 an hour with a two banger, man you must have been in the groove.
I have never cast and got the little wires but I understand what you are saying. You definetly were getting maximum fill on the mould.

Icast and if the bullets are smooth or a little frosted and have good character I am happy. They all grow the same once seeded in the berm at the range.
IOf I was to do comp shooting I might get more perticular but I have never taken having fun to that kind of level.
Ken.

rhead
09-15-2007, 09:38 PM
I check the base and check the driving bands for obvious flaws. A quick glance at the entire bullet and either keep it or cull it.
It is a matter of personal preference as to where your own point of deminishing returns is.

NVcurmudgeon
09-16-2007, 01:10 AM
Urny recently looked at some of my culls that were in the sprue box waiting to be remelted and said that I had too high a standard. As these castings were 9mm which would be used for seven yard defensive practice I agreed with him, and later "rescued" most of them. OTOH, I reserve the right to nitpick the rifle boolits!

Bret4207
09-16-2007, 07:25 AM
In addition to wanting to see Alaska, Scotland, New Zealand and the Henry Ford Museum in Detroit, I want to see Bruce in the midst of a 500 per hour x 2 banger session. My hero!

joeb33050
09-16-2007, 07:42 AM
The book, at http://sports.groups.yahoo.com/group/CB-BOOK/, in FILES, 3.5 DAMAGED BULLETS shows the fascinating results of some experiments shooting both accidentally and intentionally damaged bullets. This shows how much accuracy is affected by damage or imperfections to the bullet.
I have records of bullet weights for some 15,000 bullets. I (and you) can cast bullets of any weight from 22 to 50 caliber that weigh the average +/- .5 grains.
I weigh bullets for these reasons:
Catch and Eliminate the oddballs, weighing a lot more or less than the rest. These pass visual, but still are way out. These WILL affect group size, sometimes.
Learn about my casting technique when I cast them
Separate them into ranges, EX 123.4-123.5, then 123.6-123.7, then...
Identify and use the outliers as foulers/sighters. I shoot tests of 25 shots. If I cast 117 bullets, this gives me four sets of 25 and 17-the 17 furthest out, for the foulers and sighters.
Aside from the first reason, I can't prove and don't much believe that small weight variations affect accuracy.
Here's a picture from the chapter showing some purposely damaged bullets.
I also tested filed 22 RF bullets for that chapter.
My conclusion is that for most purposes small variations in bullet quality don't affect accuracy that much.
joe brennan

USARO4
09-16-2007, 09:35 AM
I enjoy reading the posts of the more technical types on this website, there is a wealth of knowledge to be gained, and I respect those who devote their time and brainpower to explore all the variables effecting our chosen hobby. In my day to day enjoyment of all things gun related I've found that most of my guns and bullets shoot just as well as I do. I dont weigh or measure bullets much, just enough to know I'm on the right track. The vast majority just get a visual inspection for any obvious flaws. I dont need that last fraction of an inch in accuracy but I respect the knowledge of people who have the patience to cast and reload to the finite detail to achieve it and the shooting skill to use it. I can see why newcomers to the hobby can be overwhelmed by the technical aspect of things. I would encourage them to just enjoy and learn while doing it.

BruceB
09-16-2007, 11:25 AM
In addition to wanting to see Alaska, Scotland, New Zealand and the Henry Ford Museum in Detroit, I want to see Bruce in the midst of a 500 per hour x 2 banger session. My hero!

Well dang, Bret; there's nothing very dramatic about it.

All's it takes is some organization, like having everything right at hand and the various components positioned for efficient use. After that, it's just keeping at it, with a minimum of lost motion and time. There's no frenzy or rushing-about.

The count for the last fifteen minutes of the session I mentioned was actually 134 bullets, so the REAL rate was actually 536....can you forgive me for overstating it as "540"? Note that this is NOT a "cyclic rate", like a machine-gun rated at 2000 rounds per minute but actually able to only deliver a few hundred per minute in real life. This production rate is a REAL rate, meaning that it is sustainable and practical over a period of up to several hours. The real limiting factor is my feet, which can only tolerate standing-up for relatively short periods. Gonna have to modify the method for casting while sitting-down on my high stool, I guess.

I wonder if I could add a video link to illustrate how I do it, along with the "Speed Casting" article?

44man
09-16-2007, 11:36 AM
Someone PLEASE come cut my grass so I can cast some boolits!!! All the mower tires and truck and car tires were low, had to add oil to some mowers and grease them. Found time to load a few rounds because the grass is still wet.
Then the water softener is acting up. Gosh darn it, I don't have time for anything. :neutral:

NVcurmudgeon
09-16-2007, 11:48 AM
In addition to wanting to see Alaska, Scotland, New Zealand and the Henry Ford Museum in Detroit, I want to see Bruce in the midst of a 500 per hour x 2 banger session. My hero!

Several of us on this board have seen Bruce demonstrating his warp speed casting technique. It is truly one of the seven technical wonders of the world, and the boolits so produced are all good. Here's hoping Bruce won't try casting while sitting until he invents sheet metal lap armor.