Turning lead into bullets – Part 1

by B.B. Pelletier

Reclaiming lead from used pellets

This report comes at the request of DB, though in the seven months since the last report, many of you have expressed an interest in the subject of casting bullets. In the first report, I showed you how I reclaim the lead from the thousands of pellets shot every year. But that lead isn’t enough for me to cast all the bullets I make. So there are many other sources of lead–many pounds coming from my friend Mac, who is also a bullet caster. I probably have 600-800 lbs. of lead on hand, and perhaps 40-50 pounds of tin. Some of my lead comes from wheels weights, which brings a quantity of antimony with it.

Those are the three elements needed for bullet casting–lead, tin and antimony. For modern guns, the antimony makes the alloy harder so the bullets can be propelled faster. Cast bullets can be fired at velocities up to and sometimes even exceeding 2,000 f.p.s. For black powder guns and airguns, though, hard lead isn’t required or even desired. What they need is a soft bullet that takes the rifling well and obturates (by deforming in a plastic way) when hit from behind with the powerful whack of exploding black powder. That obturation is counted on to seal the bore as the hot gasses push the bullet.

Obturate?
I want you to understand what obturation is in this instance. When a charge of black powder explodes, it’s far more sudden than the rapid burning of smokeless gun powder. The shock wave slams into the base of a lead bullet with greater force than a sledge hammer. Being soft, the lead cannot help but upset, squashing out until it contacts the sides of the bore. This is a characteristic that black powder shooters rely upon when calculating the proper loads for best accuracy. This squashing or filling of the bore is known as “obturation.”

Big bore airguns do not obturate their bullets. The pressure of compressed air is not sufficient to make lead squash and obturate. So, it’s far more important with airguns that the bullet fit tightly in the bore–even to the point of being slightly oversized. Since obturation will not happen, the lead needs to fill the bore at the start of firing. Which brings us to the subject of casting bullets.

You cannot always buy a bore-sized bullet, but if you have the right mold you can always cast one yourself. That’s why the big bore airgunner should look into bullet casting. That and the savings that goes with casting. If the lead can be acquired free or very cheap, the cost of the bullets is virtually nothing. Compare that to spending up to a dollar a bullet, and you’ll quickly see why casting is desirable. Of course, if you’re shooting only 50 big bore rounds a month, then it may not be worth the investment in the equipment to cast your own bullets.

Getting started
Casting is little more than melting lead and pouring into a mold to harden. It can be done with the most primitive equipment involving nothing more than a campfire, lead and a mold. I use an inexpensive electric furnace from Lee that allows me to control the heat very carefully. This furnace holds up to 20 lbs. of lead, which is more than enough to cast what I want. I load it with a combination of lead and tin, so the result is an alloy of 30-40 parts lead to one part tin. There will be some antimony in the mix as well, but it will be low enough not to matter. I want a very soft bullet.

Pure lead does not cast as well as I need for good bullets. By adding some small amount of tin, I boost the ability of the metal to fill out the mold. The result is a soft bullet that takes the rifling well, obturates well and fills out the bullet mold without voids and areas of missing lead. The result is a clean, sharp bullet of relatively uniform weight. I would expect to pay 40 cents apiece for the bullets I can produce for almost nothing.

I start with a pot full of metal. Starting from a cold pot, it takes 25 minutes for the metal to melt and be ready for casting. When it’s up to temperature, the pot thermostat is turned down to about 650 degrees in stages. The object is to have just enough heat to keep the metal molten. That reduces the fumes, though I always cast outdoors to reduce exposure to fumes.


Pot is three-quarters full of metal from the last casting job. To that I added some linotype for the lead and some bad bullets, plus range pickup lead bullets.


Pot is brought to max temperature for the initial melt. This takes 25 minutes.

Things I need
Besides a furnace and lead, I need a plastic hammer to rap the sprue plate, safety glasses for myself, a large towel in which to drop the new bullets so they don’t get damaged, a pair of pliers to pick up lead pieces, beeswax to flux the lead, a cardboard box for the dross and I like a large metal cooky tin cover to catch the sprue as its cut, because I want to put it back in the pot.


These are the things I need to cast bullets. Beeswax, safety goggles, plastic hammer, mold, towel to drop bullets on, metal tray for sprue, pliers, and a large spoon for the dross.

Skimming the dross
The pot started with odd bullets and other lead items. When they all melted, there was a portion of non-lead “dirt” floating at the top of the pot–just as there was when I reduced the lead waste to ingots. I use a large steel spoon to skim this dross from the top of the pot and dump it into a cardboard box. Though it’s hot, the box will not burn.

Fluxing the metal
Next, the metal must be fluxed. What that means is the separate metals in the pot must be stirred and combined into a homogeneous mixture or alloy. A piece of pure beeswax the size of a USB plug is used for this. Drop it into the pot and let it melt, then stir the metal, mixing the top and bottom parts thoroughly for a minute. When you’re finished, the lead at the top of the pot should be shiny. During casting, look at it from time to time, looking for a gray scum. That’s tin separating from the lead. When you see it, time to stir the pot or possibly to flux again.


Once the metal is ready for casting, the temp is dropped back to about 650 degrees in stages. This was the first reduction.


I bought 10 pounds of beeswax off the internet. It’s perfect for fluxing lead.


A chunk of wax the size of a USB connector is perfect for fluxing. Drop it into the pot. After it melts, stir the metal for about a minute.

Tomorrow, we’ll be ready to start casting.

68 thoughts on “Turning lead into bullets – Part 1



  1. JP,

    Very informally, with my thumbnail. I scratch the bullets after they are made. If I can leave a scratch, they are soft enough. It sounds lax, but I've been doing this so long that I know what to look for and how much antimony is going into the pot. Hasn't failed me yet.

    B.B.


  2. Hope
    My Crosman Challenger arrived Friday. I'm new to this but will post my thoughts as I use it more. A few quick things:

    - Does anyone know what kind of sling will fit it and where to get one? The Crosman rep told my my nylon Daisy sling (from a 953) would attach easily, but the accessory rail is different than the 953's. It's just a groove, not a rail. Crosman's site says they don't make any accessories for the gun. Any ideas?

    - If you are filling it with the hand pump you may need to do it w/ the gun cocked if it is the first fill. This nugget of wisdom is buried in the manual only under the section about filling it w/ a pressurized tank. So I just spared you hours of late night frustration figuring out why the neither the pump nor gun will hold pressure.

    - So far the only thing I don't like is the sound it makes when it shoots – a little boingy and toy-like. I haven't touched any of the factory adjustments.

    Don


  3. Once again I am amazed at the knowledge we can get from this blog.
    I'm sure one day we'll be getting the meaning of life post.
    How about a post on how to win the lottery (so we can buy more airguns) ?
    There is enough info for a few books in here (or a really large one) u should do it, I'm sure it would sell REALLY well.

    J-F

    p.s. the verification word is trylogi I think it's a sign u should make ur books a three part thing.


  4. RE: American rifleman article

    A while back there was discussion about an improved formula for Greenhill's Twist formula.

    Another formula can be found in paper:
    "A New Rule for Estimating Rifling Twist
    An Aid to Choosing Bullets and Rifles"
    by Don Miller

    From: Precision Shooting, March, 43-48 (2005)

    at:
    http://www.jbmballistics.com/bibliography/articles/miller_stability_1.pdf

    One of the references which he lists is:
    Col. E. H. Harrison, "Rifling Twist," American Rifleman, November 1965, pp 52-56.

    This the Nov 1965 article on twist rate which the page numbers were needed. The name is also different than expected.


  5. Don,

    The Daisy 753/853/953 all do not accept a target sling because they have no accessory rail like the Challenger. They are all underlever single strokes, which means they have pump levers where the forearm accessory rail would go. The only place a sling can be attached to a 953 is the barrel, forward of the forearm.

    The Challenger has a standard forearm accessory rail that will accept standard target rifle sling swivels. Pyramyd Air doesn't carry these, but Champion's Choice is where most target shooters get them.

    http://www.champchoice.com/cat-Slings_and_Accessories-620.aspx

    B.B.


  6. RE: Blown Skirts

    BB and anyone else…

    In the Cardew's book "The Airgun from trigger to Target", page 184, they show pellets fired from rifles of different energy. The pellets from the high energy shots had their skirts blown way out. The cone shaped tail had been blown more into a more cylindrical shape. Unfortunately the Cardew's didn't share any measurements of the pellets.

    The high energy springer seemed to put more stress on skirts than the high energy pneumatic. I assume that this is because the springer accelerates the pellets faster.

    I only have some "low" power pneumatic guns, and medium power pneumatic guns. Not exactly what you need for this test.

    (1) Wouldn't this change the BC and flight characteristics of the pellets?

    (2) Any follow up work that you know?

    (3) Are modern PCP's shooting pellets at 900-1000fps shooting so hard as to blow the skirts out too much?

    I was wondering if this could Jane's problem? As I remember, she was shooting some pellets that group well around 600fps, but then the groups get big when she pushed them to 900 fps.


  7. Thanks BB. Any particular sling/handstop combo you would recommend w/ the Challenger. I have problems w/ slings sliding down my arm.

    Also, re: the sound made when firing, is that just a function of the lower pressure? The only other target rifles I have shot are the Daisy 953 and 888. They sound a lot crisper and not so springy. Just want to make sure there is nothing set wrong in my Challenger.
    Thanks,
    Don


  8. Hello BB!

    You're great. But–no fault of yours, after reading your column for months…I am SO confused.

    What are the best 3 rifles I can buy? Number one criterion: 1)MUST BE QUIET. Other criterion: 2) accurate, 3)shoot at least 550 fps, 4) cost less than $150 (or slightly more). (Love to know your opinion on pistols too–especially difference between Daisy 717 and 747. Is the 747 worth the extra money???)

    Thank you so much for your obvious expertise. Would love others to respond as well.
    CCOO





  9. Hi Herb,
    Mostly I want to target shoot from/within an apartment to a (sort of) private backyard. 22 would be my preference, but I'm open to caliber.
    I have some experience (used to be a crack shot), but am getting back into the sport. I have a Daisy XT, old Daisy Powerline 1200, and Benjamin 392 22 caliber and another Crosman pistol–but all way too loud.
    I've thought about the Crosman 1077 or Storm, but don't know.
    AND, I should have said–prefer CO2 or break barrel–NOT a pump.
    Thanks for the quick help.
    rob


  10. Nice read BB. I've done some bullet casting in the past too.I still have all my bullet molds.I don't know about the rest of the country, but in my state, Wa.,lead wheel weights are going to be dissapearing.They may switch to zinc, or steel. I used to use wheel weights sometimes.

    jon


  11. Jon,

    If you follow the link at the top of this report back to the other blog about reclaiming lead from used pellets you'll see that I also melted about 40 pounds of wheel weights. Getting harder to find them anymore.

    B.B.


  12. Maybe I'm not reading close enough and misunderstanding what has been said (it is Monday), but the Avanti 853c comes with a shooting sling that attaches via a clamp to the cocking lever.
    It is a bit of a PITA though, as when it is snugged up on your upper arm you it is not long enoug to comfortably cock the rifle…each time you cock you have to drop the sling to your forearm and repostion it when ready to shoot.
    CowBoyStar Dad


  13. BB,
    Definitely useful information, as always. I picked up a bunch of cheap .50 cal. balls at Friendship, but I think casting balls is something that is doable for me.

    Herb,
    Thanks for finding that citation. Matt should be able to get the article now.



  14. Rob – BB had given strong reviews to the Hammerli 490. It's a .177 springer, which is probably going to be quieter than CO2. It falls a little below your min ft/sec requirement but It doesn't sound like you're looking for a hunting gun so it should be adequate. The IZH 61 would probably another good one to look at. Both fall lunder you price limit and I've heard nothing but good things about both, fo what it's worth.

    -Aaron


  15. yeah–Aaron, I've read about both of those guns (hammerli and izh). they look good.

    BB–if you have the time, I would love to get your opinion on this. 3 best rifles that are QUIET–and secondarily accurate, non-pump, 500 fps+, and (hopefully) under $150. I know–the perfect gun for nothing is a dream, but mostly looking for extremely quiet target rifle.

    Also, is the Avanti 717 as good as the 747? Why spend the extra on the 747?
    rob


  16. BB:

    "I probably have 600-800 lbs. of lead on hand, and perhaps 40-50 pounds of tin."

    Remind me never to help you move… 8-)

    Sent my Marauder back to Crosman; it will probably be returned while I'm out of the country. So no update for a while.

    Keep up the great work!


  17. Rob,

    I'm in over my head now…but hopefully BB or some of the other guys can now help more.

    I can perhaps provide some perspective.

    For $150 rifles I don't think there is much done to silence them. Expensive PCPs ($500+ to sky is limit) have built in silencing ("shrouds") which cannot be removed. Thus the rifles skirt the laws on firearm silencers.

    It will be a lot easier to get a 0.177 pellet going 600 fps than a 0.22. So for just plinking (and to keep the costs of pellets down!!), I'd go with a 0.177. You can probably even find 0.177 Crosman hollow point pellets at a local box store fairly cheaply. The CP HP have generally been known to shoot well. You gun may vary of course.

    If you mail order the gun order some JSB pellets and use them as the gold standard. They are likley to shoot about as good as it gets, but the pellets are expensive, and they are often on backorder.

    The other thing that I'll say is that I've proven BB's adage about guns "You don't get what you didn't pay for…"

    The inexpensive scopes, generally 4X, that come with $100 rifles, are not particularly fussy about eye position. Of course if you move your eye position, then the POI changes. A more expensive scope, which could be a later purchase, would help. (Springers eat firearm scopes, so if you get a springer be sure and get an appropriate scope.) A higher power scope with AO should greatly improve your group size for target shooting.


  18. Rob,

    You pretty much have them, except that I would add the Mendoza RM 200 in with the IZH 61 and the Hammerli 490. And it does come in .22.

    Definitely stay away from pneumatics and CO2 guns, because they pack the noise.

    Too bad about the price, because you really want a Marauder.

    The 747 is more accurate than the 717. It is worth the extra money? Well, how much do you value accuracy, and how good a pistol shot are you? Many people may not be able to see much of the difference between the two, so the 717 would be good enough.

    B.B.


  19. Okay, I need some input.
    I'm about to make a big dollar purchase and I don't know which way to go.
    I like both target and field shooting and have a number of what I consider to be budget guns (853c, Gamo Compact, Slavia 630 and the Nightstalker).
    Here's my regime for target shooting.
    Once I get home from work and 'destress' I'll head to my basement (which has a range that just manages 10m). I alternate…one day pistol, one day rifle. I take 15 sighters than proceed to do 20 shots. I have hit a wall it seems, which I think is due to lack of equipment and coaching. On both pistol and rifle, using standard ISSF 10m targets the wall I have hit seems to be 188/200 (pistol) and 192/200 (rifle).
    Being in the northern hinterland (Edmonton, Alberta, Canada)…a city with NO official air-rifle community I have no one to compare to…I don't really know if these are good scores or not.
    So…(not that anyone but myself can answer this question) I'm thinking of moving up to either an FW700 rifle or a Steyr LP.10 pistol. What I'd like is some input from anyone familiar with competitive shooting…are my scores worth 'trying harder'.
    Conversely, if not I have my eye set on a FX 8000 Revolution.
    Any thoughts would be appreciated.
    CowBoyStar Dad


  20. CBSDad,
    Sounds like good shooting to me. 192*3=576, so only 24 points separates you from an Olympian:). I don't claim to know anything, but it sounds like you will get enough use out of a 700 to justify the cost, and you can probably sell it with little loss if not. Maybe Canadian Olympic team has tryouts in nearby Toronto or Vancouver:).


  21. CSD,

    You are shooting a 470/600 in a 10 meter match with that pistol. I bet a cookie that from the US of A I can TALK you up to a 530. I can't do that with the rifle.

    I did just that with a guy in New York City (you think Edmonton has no airguns?). Inside a year I had him up from 480 to 535, at which point he forgot himself and passed right by me–the ingrate.

    The Steyr LP10 is one of only two air pistols I would consider. Personally, I like the FWB P44 a little better, but that's just me.

    B.B.


  22. Hey–first of all–THANKS very much to all for their guidance.

    BB–I would LOVE to have the Marauder. Dream gun. Laughing. Just too steep for me to justify right now.

    Again, huge fan of the site and read it often.
    rob


  23. BB,
    How did you figure CBSDad's 470/600? I thought a match would be 60 shots, so I just multiplied his 20 shot rifle score by 3, but there must be more to it than that, since that method results in 564/600 for pistol and you say 470. What am I missing?



  24. BB,
    No problem — I was thinking he was really good with that rifle score. Of course I'm rooting for rifle, so he can send me the old ones from his lucrative endorsement deals someday:).

    Of course, putting 60 shots together is probably a sizable part of the challenge…


  25. Thanks for the comments guys (me blushing).
    Many years ago (like 20) I used to shoot semi-competitive rimfire rifle here Edmonton. There were about 10 of us total and I was told I was very good.
    Life got in the way…and just a couple of years ago I got into air-rifle.
    I've had an idea that I'm doing well. I'll read something someone has posted on the other forum I visit (a very boring target forum) and someone will say something along the likes of "when I shoot a 7 it totally blows my concentration"
    In all honesty, especially with rifle the last time I hit the 7 ring was when I accidently dropped my 853 and knocked the front sight a bit.
    But shooting in a vacuum has given me nothing to compare too. As well I know that nothing will knock 10 points off your score than actually shooting in competition with other real live people watching.
    I just don't think I really want to get involved in serious competition…there is no way I would take away the time from my two young sons that would entail.
    I will just have to give it more thought.
    If I decide to go that route b.b. (or anyone), do you have any experience with the FX airguns?
    They seem real nice.
    I figure everyone should have one REAL NICE gun…that's why I've got this dilemma.
    Thanks all
    CowBoyStar Dad


  26. Hi all,
    Field target report..

    (I mistakenly posted this first on the weekend blog.. so I'm putting it here too.)

    I came in tied for third.. shooting in the open class against folks with harnesses and some with higher ft. lb guns.. (I'm shooting the 12 ft lb USFT and no jacket or harness… that's the international class)

    Here is a link to a report and some pics of the Washington state championship field target shoot.

    report:
    http://www.network54.com/Forum/451309/message/1253461470/Washington+State+FT+Championship

    pics:
    http://www.network54.com/Forum/451309/message/1253514047/Some+pics.

    Next Sunday, the group from the bay area and one or two of the Washington club will come here! Yeah.. I'm gonna make a fun course for them.

    This is just toooooo much fun!

    Wacky Wayne, MD. (match director) .. not doctor!
    Ashland Air Rifle Range


  27. you know, if my wife ever sees the new desert eagle co2 video, I will never be allowed to go out shooting again….lol!!!!

    I have to admit, the model in the vdeo is a little more better looking than paul….sorry paul.

    btw….does the lipstick in camo color?


  28. CowBoyStar Dad,

    That's some great 10 meter shooting! Well done.

    I've never owned an FX gun. You mentioned a FX 8000 Revolution. Never heard of an 8000. Looked at the Revolution awhile back since I thought a semi-auto would be interesting. The people that owned them complained about how twitchy they are. Constantly getting dirt, pellet debris and lead dust in the blow back and the gun won't cycle. They blow seals regularly too.

    Volvo owns an FX Cyclone and sings its praises. I'm now toying with the idea of an FX Ranchero Carbine since it uses the same hardware as the cyclone.

    Hope this little bit helps.

    kevin


  29. Wayne,

    Congratulations on 3rd place!!!

    If I remember correctly, it was just over a year ago that you said, "What is FT?" Then B.B. did an article on how to set up an FT course and you were off and running. What amazing progress you have made.

    That course in Washington you just shot is beautiful. I really like the sasquatch set up. Need to hit the tree first then the big foot. Great fun.

    Keep making us proud.

    kevin


  30. Kevin,

    Thanks, I am having loads of fun! There is really a great bunch of folks in this sport… Everyone has been great to get to know.

    I'm still learning the fine points, and breaking new ground with my "carpenters" holdover style. The BSA platinum I got has a target dot, and no mil dots.. so I've set the 10-50 power scope down to 20 power, and left it there. (dark targets.. no problem).. I dialed the turrets to a zero of 22 yards…. and haven't changed them too!

    I've been writing the holdover on the side focus wheel in inches I see in the scope.. if I see a 1" kill zone on a target at 55 yards, I need a holdover of 2-1/4", so I use the kill zone to gauge the holdover, and then check the wind, and fire.

    I've had to do it over several times, because I run out of room on the side wheel tape.. so now I'm just putting most of the spots and guessing in-between… It's a funky system, but that's me.. I just need more practice to "learn" my marks on the side wheel…

    speaking of which, I'm off to practice.. darn, I've got to walk 200 yards down to the range.. :)

    Wacky Wayne, MD
    Ashland Air Rifle Range


  31. Mr. B.

    Thanks for the Tee shirt ideas!

    I'm making a list of stuff to write on them and checking quality and pricing….

    Keep them coming folks!

    Wacky Wayne, Ashland Air Rifle Range


  32. CBSDad,
    Don't worry about the particulars — it won't work out at all if you don't try:). Let the boys "help" you (they can score, etc.) and take one or both along if you go to a match. Offspring are always (secretly) impressed to find their old man has some widely recognized skill apart from laying down the law:).

    Wayne,
    #1 in Oregon, #3 in Washington, and I'm betting you'll make a good show in the Left Coast Cup that you mentioned is coming up. I could tell when you talked about how much you practice that you might raise a few eyebrows!


  33. BB; An old trick to help fill out the bullet in the mould as it cools is to "Smoke" the mould first. This is done with an old wooden kitchen match.

    Just lite it and hold it under the mould cavity. One match per side.

    It really helps with pure lead.

    Mike


  34. Don, let us know how the challenger does…..cool you can charge up yourself.

    Herb, thanks for the link.

    Rob, I shoot a 953 indoors at 10M. It's a singe pump, really quiet and in the upper 400s fps. It doesn't have a lothar wather barrel like the 853/753, but the 953 is about 1/3 the cost. Add some 10m sights or a scope and you may still be within budget.

    The 747 has a lothar walther barrel and the 717 doesn't. without the l/w (choked barrel) you can still get good accuracy, but the airgun will be more picky wth pellets and sometimes end up with more expensive pellets to shoot and cost you more in the long run for accuracy.

    I wouldn't mind a 747, but a izh46m is what I would recommend for the ultimate in a budget 10m pistol.

    Nice shooting CSD!!!! I'm going to have to get some targets and put my 10m sight back on my 953 and figure out how to score some shots….but wow..I'm pretty jealous….

    wacky wayne wacky wayne wacky wayne…(three cheers) wtg!!! I wish I had the time….FT shooting sounds fun, but I am in the very affordable AR and 1 target crowd.

    FT AR, 10M AR and hunting is all I think about and love them all. I did take some time off and will be a shooting fool pretty soon.

    I wonder if this is how golfers feel about golf. I never liked golfing, I'd rather be shooting any day.

    TU – read your blog, funny…..I didn't catch and release and now I have been married over 14 years….but they've good ones so far…………

    BB….as always keep up the good work…I've seen your blog has been hitting interest from shooters and forums all around the world…well I helped a bit….but now they talk about your blog on their own….lol!!!!

    All the best!!!!!!!!!

    AJ

    http://www.youtube.com/watch?v=Q8uGAFFQonM

    one song I will never change the words to…….


  35. B.B.

    This actually makes it seem like casting lead is possible. I couldn't give a higher compliment. I like that electric furnace.

    Wayne, well-done with the field target.

    Matt61


  36. Statisticians! Thanks for your input. In the search for certainty in the world of uncertainty, I first want to quibble with the statement that group size will increase with number of shots and that an infinite number of shots will create an infinitely large group. I don't see this at all for the simple reason that with a rifle in a rest, I feel certain that I could hit a garbage can lid at 10 yards an infinite number of times with not one single shot falling outside that area. Basic physics says that with a barrel in workable condition and a standard size pellet, it is impossible for the pellet to deflect sideways beyond a certain angle. Finally, I have looked at many representations of the bell curve, and while equivocal in some cases, it looks like it is not infinite but does terminate. The garbage can lid scenario is an extreme example, but it does suggest that for a given distance, there will be some limit to group size no matter how many shots you pour into it.

    What is the limit to group size? 30 shots has been raised as a number. That seems reasonable to me. If in fact, it is not absolute, I suspect the amount of useful information contained in the 30+ groups is of rapidly diminishing value. I'm curious what that extra information would be.

    Supposing that group size does indeed converge for an infinite shot number, the question then is whether there is a pattern to how the shots are distributed. I think that common experience would suggest that this pattern is not random and that it is related somehow to number of shots. The more shots, the larger the group is an empirical result (up to the limiting size). What are the objections to supposing a normal, bell-curve distribution? I gather from the comments that an actual physical shot distribution is complicated by all the factors that go into a bad shot—bad technique, the sun, the wind, the equipment and so forth. I agree. As I mentioned before, the normal distribution is just a heuristic device. When you superimpose on it all of the possible causes of a bad shot, then you get the actual physical group. However, here I think a powerful simplifying effect appears. Unless, there is a systematic problem with shooting which should be identifiable (flinching with a .45, nick in the muzzle, bullet run-out, throat erosion, badly-fitting pellets, dirty bore, loose sights, excessive nervousness), then the sources for individually bad shots (non-systematic by definition) must cancel each other out. So, the more you shoot the better, not worse, is the normal distribution as a model for shot distribution. Finally, the Aberdeen Proving Ground which does weapons research for the government assumes a normal distribution to shot groups according to a reliable academic source, and what is good enough for them is good enough for me.

    to be cont. ….

    Matt61


  37. Statistics contd.,

    I think our purposes are a little different here. I didn’t follow the notation used, but it would seem that a lot of the mathematical analyses described was aimed to identify the statistical significance of group sizes and shot placement; that is, to sift out what was random deviation from systematic cause. I have no doubt that there are sound theoretical bases for doing that. However, the ultimate goal of it is…probability. It is fundamental to the field that you will never fully predict an individual/trial shot. All you can do is refine your sense of the likelihood that it will behave a certain way. To pour endless effort into an open-ended result like that is a legitimate activity, but it saps my motivation rapidly. It is even less attractive than hand-pumping a pcp.

    More appealing to me is to look at obvious patterns offered by the science of probability that have a clear practical value. For example, looking at half of a normal distribution curve, say the right side, it’s clear that approximately the middle portion has an obviously linear, downward slope. Exactly what the borders of that portion are and whether the slope is exactly a straight line or a teeny tiny deviation from it does not alter the fact that a significant portion of that curve looks a lot like a line identifying a linear increase. In our physical situation, this implies that for a given number of shots the group size will increase in approximately linear fashion. Supposing that group sizes plateau in the neighborhood of 30 shots—it looks like somewhere between 3 and 17 shots—the group sizes should grow in approximately linear fashion. No doubt, statistical techniques can refine this picture to an arbitrary degree about just where the linear range begins and ends and just how much the linear increase corresponds to a geometric straight line, but I don’t see anything to alter the basic characterization.

    Matt61


  38. Off topic: I recently watched "Border Incident" a DVD I rented from Netflix. The boss of the bad guys, Owen Parkson, is a dead-shot with an over-lever pellet pistol. This is the second '40s-era movie that has had pellet pistols. The first was the "Bowrey Boys 'Neath Brooklyn Bridge." I couldn't tell the make of either pistol.

    –Witt


  39. Mike,

    I've certainly read about smoking the mold many times, but I've never tried it. One time I opened the vent lines a little and that seemed to help.

    How many casts do I get after I smoke the mold.

    B.B.




  40. Matt,

    The number 30 as a sample size is not arbitrary. It is a sample large enough to give a high degree of confidence that the sample represents the entire population of data. It can never be one-hundred percent the same, of course. It's just a shortcut that is recognized throughout the scientific community for what it is– a sample that can be trusted to project the same as the population from which it was taken to a high degree of confidence.

    Of course there are many ways the sample can be corrupted, but that was never part of this discussion.

    B.B.


  41. B.B.

    Mechanically challenged as I am, my praise was intended to be of the highest. :-) I'll look for the video.

    Thanks for the clarification of the 30 shots. Yes, indeed, I am keeping probabilities separate from various corrupting agents, and 30 sounds like it does the job that I intended for it. I am not one to sweat the details beyond a certain point.

    Matt61


  42. Matt,

    You miss the point. Look at the "normal curve." It extends INFINITELY in both directions.

    You obviously can't have a negative group size. As I said, group size would NOT be a normal distribution. However you'd have to shoot a lot of shots to get enough data to say that it isn't so….

    You shoot 10,000 shots in your garbage lid. On shot 10,001 the group can't get smaller, it can only get bigger. You get tired, it is getting dark, a hurricane sweeps through, you're still shooting at the lid at age 85 and your hands are shaking, or the gun wears out from shooting so much. As you shoot more the group size can only get bigger.

    But that is really the point. If you shoot enough shots you get to the point where the group size increases very very slowly. If you only shot one shot, nice "group". Look at a target sprayed with pellets. Just by chance there will be two close together. That's you "best" two hole group, and so on. As the number of shots in the group increases, it is harder and harder to get "lucky."

    Sorry you didn't follow the discussion on range, but that is statistics. The whole discussion on range DID assume the normal distribution.

    ———–
    RE: sample size of 30

    If you sample a normal population you're generally interested in calculating a mean and a standard deviation. A sample size of 30 is regarded as a "reasonable" sample size to get a "reasonable" estimate of the standard deviation. The standard deviation you measure isn't the "real" standard deviation of the whole distribution, it is only your estimate of it based on your sample.

    In other words, you take two samples of 30. Are the mean and standard deviations of the two going to be EXACTLY the same? No. Close, but not EXACTLY the same.


  43. Matt and Herb,

    Here is a different take on group size from a statistical standpoint.

    It finally dawned on me that shooting any size group and measuring group size is basically like looking at just the "range" portion of the old SPC "X-Bar and R" charting techinque. In this case X-Bar is the mean of the data, or the X/Y of the average POI, and the R is the range of the data, or the group size in terms of maximum total spread rather than maximum range away from the average POI. We completly ignore the X-Bar data and only look at the range – as Herb said, we throw out a lot of good data.

    I think I can dig through my old statistics books some time and find a good way of converting this observation into something usable, but I do know that the answer will involve a detailed baseline for comparison, like in Herb's example from the other day.

    In the end, I think the goal here (at least mine) is to find a good way to use the data we are used to collecting and comparing to be able to make predictions on likelihood of making a given shot. After all, it is very possible to have a group size of 2 inches out of a 10 shot group, but have anywhere from a 20% to a 95% change of hitting a target area only 1 inch wide, depending on the spread of the shots. Being able to easily know that liklihood is key, I think.

    Alan


  44. Great article,B.B.!! I've never cast any bullets, but it has always interested me as a reloader. I guess, that part of me feels incomplete because I haven't tried casting yet. Keep up the good work!

    Thanks,
    /Dave


  45. CSB
    Way to put 'em in there,and congrats on
    bringin the kids into the sport
    RESPONSIBLY too,my respect to ya.

    Wayne
    It's great to see someone with your
    enthusiasm for the game, keep us all posted on your success and let us know
    when the T-shirts/ball caps are ready.

    BB
    It's odd but wheel weight finds are
    dryin up around here too.There are only a coupla old style full service stations
    that will save 'em for ya that we can find.

    BG
    Those screw caps were on the gun when I
    got it from Vince,can't say if he put 'em on or if they came with the gun.
    Told ya we reconfigured that rifle:)
    Almost all the work and definitely all
    the details are due to my uncle.He
    really loves woodworking.
    Speaking of wood work, I have a good file on some really unusual handcrafts
    that are awe inspiring.If you're
    interested I'll put them on picasa or
    E-mail them so you can share 'em.
    Just let me know.


  46. JT,
    Either put it on picasa for everybody or e-mail me at bgfarmer0_at_gmail.com or both:). I'm going to try another Kentucky rifle (finally found some "art" that I like:)), so any woodworking information is more than welcome. The weekend blog with the ball reservoir Kentucky really has me going, too, just can't figure out how to make a springer look that pretty:).



  47. Wayne,

    way to go. I hope I speak for all of us on the blog that we're all proud of your accomplishment and look forward to results of your future matches. Just wondering if you've reached the "Cowboystar Dad wall" where you now need the harness and other little tricks to move higher to displace the two guys ahead of you?

    Anyways, congrats again.

    Fred


  48. BB; Yesterday you asked how many casts I get after smoking the mould. It should be good for a "normal" session. I have not found the need to redo it while casting. Give it a try, it helps!

    Mike


  49. Fred,
    I haven't hit that wall yet. I'm still working on the low hanging fruit of my BSA scope with target dot cross hairs.. no mildots… and no clicking for me!..
    I guess at the holdover and wind adjustments and go for it..

    Walls are for banging heads on… right?..

    But really though, practice can improve my scores a little more.

    Especially in a wind on long shots.. that's were the 12 ft lb no harness game gets tough.. but do it over and over again, and soon it becomes easy..

    ..case in point….My standing has really improved, at practice I knocked over the 1/2" kz at 14 yards and the 1-1/2" at 34 yards twice each this evening… amazed myself!.. and there was a mild wind too.

    I'm sure the walls are coming, I'm just to blind to see them!

    Wacky Wayne, MD.
    Ashland Air Rifle Range



  50. I have poured lead several times the way you desribe it, but I have never used Beeswax. One of my molds is a motorcycle with rider and I have trouble getting it to fill with lead/tin mix. If I used some Beeswax as you explained do you think I would have better luck filling this mold?

    Ron


  51. Ron,

    Several things to try. The beeswax is to help flux the metal. The tin in the pot helps the lead fill out the mold, and fluxing mixes the tin into the lead. You might also try lighting a kitchen match and letting it smoke up the interior of your mold. Apparently that helps fill the mold.

    Finally, if that mold refuses to fill it's probably because the air cannot escape. Try enlarging the air escape lines on the mold face with a pin or a sharp hobby knife. Be VERY careful not to enlarge them too much or you will start having fins on your castings.

    B.B.


  52. I tried the smoking of the molds, only I used candles. I tried keeping the mold on a hotplate to keep the temperature up while I poured. I tried several different mixtures of tin to lead. I wore welding gloves so I could pour several times quickly. Even after 20 or so tries, I might get 2 pieces that is worth keeping! I tried enlarging the air escape lines, maybe I should try to enlarge them a little more.

    Since you talked about using Beeswax, I thought maybe it would help me since that is one thing I haven't tried, or even knew about.

    Ron


  53. Ron,

    Okay, you have done everything that I know how to do–except for fluxing the metal. Give it a try.

    I'd like to hear whether it makes any difference, when you get around to casting again. No rush, though.

    I will tell you this, Elmer Keith wrote about some molds that simply would not cast no matter what was tried. You may have one of those.

    B.B.


  54. Ron,
    The old guy that showed me how to cast bullets used a candle to smoke the mold and he also used bees wax to flux.

    You do need to flux to get the metal to mix right. Same as flux for solder or welding.

    We would resmoke only if defective bullets were cast. You're also correct keeping the mold warm is a big help. We just cast a few throw away bullets to warm the mold. The kept casting to keep the mold warm.

    My shooting mentor was a very kind fellwo… miss him a lot.

    DB


  55. Thanks, I will definitely try Beeswax the next time I pour. It may be a while before I get back to it. I sometimes will pour lead in the winter when it is cooler and there is not so much going on.
    Thanks again, and I will continue to read your blog, it is entertaining and educational.

    Ron


  56. When are you going to finish your testing and report of the Evanix Blizzard? Am waiting to read it. Especially what pellets you find work best with the rifle.



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