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View Full Version : Shiney vs. Frosted - my Observations



Ohio Rusty
05-03-2007, 01:37 AM
I had an opportunity to melt down some of these wheelweights I've been collecting this weekend after chores were done. After the lead was cleaned and fluxed, a tad bit of pure tin solder was added. During the casting session, I noticed, or should I say felt the sprue plate getting easier when cutting the sprues from the boolets. I also noticed the boolets were getting frosty. That was telling me I was at max heat for casting. I examined the boolets closely and I was surprised with what I saw. I'll share my findings with all of you in the pic below. The 3 boolets on the right are frosty, the two on the left are shiney. The frosty boolets on the right show something interesting. I know why the sprue plate was getting easier. The sprues weren't being cut, the sprues were being 'broken' off the bottom of the boolets. If you notice where the sprues were, there is a crater there where the sprue broke away from the bullet exposing a crystalline structure instead of a smooth metal like the boolet on the left. When lead gets too hot, it must change somehow actually changing the structure of the lead becoming crystaline and brittle. I noticed several other frosty boolets with parts of the bottom driving band literally cracked off, because they were too brittle. I now know when boolets start showing that frosty appearance, that is bad news and I need to lower the heat or cool the mould. Shiney is the way to go for me as that seems to make the perfect boolet, inside and out. Others mileage may vary .....
Ohio Rusty
http://img.photobucket.com/albums/v372/OhioRusty/100_0705.jpg

BruceB
05-03-2007, 02:01 AM
There's nothing wrong with frosty bullets.

In your case, the increasing mould temperature means that you should wait a bit longer before cutting the sprue. The craters are being "torn" in the base, not broken.

Many of us actually prefer frosty bullets, and if you don't care for their appearance in the loaded round, a few seconds of polishing will shine them right up.

You may want to try cooling the sprue on a wet pad before cutting it off, as this will positively prevent the craters AND eliminate any possibility of smearing molten alloy across the mould top.

cbrick
05-03-2007, 02:33 AM
BruceB is right, those bullets aren't broken. The alloy wasn't quite solidified yet and you tore the sprue rather than cut it. As the mould gets hotter either wait a bit longer before opening the sprue or do as Bruce suggests and use a damp cloth to cool the sprue every few fills to keep the sprue plate cooler.

BruceB is right, frosty isn't a bad thing, depending on the mould, they all have a bit different personality, some will frost the bullet a bit at the same temp that others don't with the same alloy. A few of my moulds won't give me a decent bullet without a bit of a frosty appearence, my SAECO 31 cal 180 gr for one.

Your shiny bullets from the cooler mould is when you will get the most weight variation in the bullets. Bullet weight should even out more as the mould gets up to full operating temp. I cull all bullets from the first 8-10 fills for this reason plus I pre-heat the mould on a hot plate or the casting pot edge first.

Rick

Lloyd Smale
05-03-2007, 04:50 AM
frosty isnt bad but watch for fillout. Using lead tin alloys when the mold start getting hot to the point that your bullets are frosty its real easy to get voids in the sides of your bullets. Especially using steal molds.

Bass Ackward
05-03-2007, 06:37 AM
[QUOTE=Ohio Rusty;178973] When lead gets too hot, it must change somehow actually changing the structure of the lead becoming crystaline and brittle. Ohio Rusty[QUOTE]

Rus,

You got the mold hot enough to start burning the tin out of your mix. Tin aids in the distrobution of antimoney evenly throughout a bullet which is why is makes it more ductile upon impact. Loos of tin will allow breakage at weak points which is why your bases appear as they do. Simply waiting longer will make this not happen, but the weakness is still there.

What you will find is that if you wipe off the frost with a rag, (it comes right off and understand that your barrel is going to wipe it right off because it offers no resistance or strength) and measure your bullet diameter, if your mold was steel, you will have lost some diameter depending on the percentage of tin in the mix. If it was an aluminum mold, you may have gained some diameter do to the expansion characteristics of aluminum as the mold gets hotter.

But the trouble I have with frosty bullets is knowing at what stage of "Frosty" you are actually at. Also, tin burn off occurs unevenly based on hot points in the mold. These occur at the top of the mold, normally the base, as heat rises and in between the cavities if you are running multiple cavity molds as one cavity tries venting into the next. That's why Veral (LBT) has a vertical channel in his molds between the cavities to prevent that from occurring. This is a big reason why steel guys always seem to have lose checks and aluminum guys can't get'em on. They couldn't see the frost coming and were losing diameter even before the frost occurred as heat rises. And as the molds get that hot, stresses from the manufacturing process can cause cavities to move outta round as this never seems to occur uniformly. Weighing your bullets will not catch this imperfection as they will still weigh the same.

Pretty soon the frost advances to a stage where it looks like your bullet has salt on it. And the amount of tin in your mix makes this loss greater and unpredictable. By the time you see this stage of frost, you have lost several .000 of diameter and your bullets will be outta balance.

I have a thermometer to measure the temperature of my mix. That I can control. I know my mold has a working temperature range where it delivers acceptable weighted and spec'd bullets. The problem is that each mold is different. I can not monitor the temperature of the blocks and thus control my tin burn off so I am better off not. If you are just running WW that hasn't much tin to lose, you are OK assuming your mold doesn't warp up there. Cook it. Tin loss is minimal and only means a couple of tenths.

Personally, I use frost to tell me when it is time to slow down and use multiple molds to avoid it entirely.

Bret4207
05-03-2007, 07:12 AM
Regardless of the theory on what happens to the alloy when we get to the frosty stage, I know that my best boolits often need to be slightly frosted. I get better fill out and less variation in weight with frosty boolits. As was mentioned my Lee moulds almost require a bit of frost to get good fill out. With a different alloy this might change, but I'm pretty much a straight WW with a bit of tin or solder (and I mean a LITTLE BIT) added kinda guy. This enforces my belief that casting is as much an art as a science. If it were a science then everyone would have the same results with like equipment and alloy. I can't even get the same results every time from 2 cavities in the same mould! To me this is what makes it interesting.

Char-Gar
05-03-2007, 08:17 AM
Yep Rusty... No doubt about it, you are cutting a wet spru.

Bass Ackward
05-03-2007, 08:21 AM
I can't even get the same results every time from 2 cavities in the same mould! To me this is what makes it interesting.


Well Bret, I figured this would stir up some feelings, but it's something people need to think about if it applies to them. let me kick the horse a little harder.

If 50 yards is all you want, you can ignore 80% of the recommendations on this board. you can size off center, mold crappy bullets, use cheap lubes, ets. But as Montana Charlie likes to point out, eventually you may want to move on out. Look at long range competitions. How many guys use a mix with antimony vs how many use straight lead / tin of some configuration? That is because the bullets balance better. Then they fly better as outta balance bullets will eventually start to wobble and lose BC and then they start to string at longer range. The wider the meplat, or I should say the worse the BC, the sooner this problem occurs.

Old timers believed in single cavity molds because they couldn't get the same quality bullets from two cavities. Why? Tin was very popular with them so they saw a big difference in cavities. Their bullets were unbalanced so segregation made a big difference. So did indexing in every stage of the process. But then they often made it worse by marking the cavities.

Look at LBT molds. Veral has put a lot of thought into his molds. I mentioned about the vertical groove between cavities venting the heat up instead of into the next cavity. Look at his thin sprue plate over the cavities. Steel holds heat that can build up. He uses very thin steel over the cavities so that the only heat is from the sprue and so they can cool faster between pours. So his molds produce a superior, "more uniform" frosty bullet. This isn't true for any other brand of mold.

Remember Starmetal? He believed that faster twist rates were needed for better accuracy especially at longer range. In truth he was correct. The more outta balance your bullets are for what ever reason, the faster you have to spin them to maintain stabilization. So in truth when we say what twist rate will stabilize a bullet of a certain weight, we should say out to a certain range that only you will be able to experience depending on the quality and design of your bullets. That's why I always say the slowest twist rate that will stabilize the bullet. If that's a 7 twist, then so be it. You have to do what you have to do.

In the past, Lloyd has said that he sees WDWW break more often than lino in impact with handguns. That is because lino has more tin to blend the antimony better. And if you burn out what little tin making frosty bullets with what little you have in there trying to get a harder bullet, this adds to the weakness upon impact. Add tin to WW and your bullets don't develop the internal cracks that you hear about with frosty bullets and so it hangs together better at impact. Because it is more ductile.

So many shooting issues work around molding issues. Molding issues are related to the heat and casting method people use because of the personality of heated molds, you have to do what you have to do to get the best "compromise" bullets possible and then work to make them perform as best as possible. My molds don't require that much heat to get good quality bullets. And I focus on hunting where I want uniform expansion and soft, self healing bullets, so tin is important to me. If it doesn't matter to someone because of how or what you shoot, then I have wasted my time.

JSH
05-03-2007, 08:27 AM
I have cussed and discussed frosting. Have came to my own conclusion frosting belongs on cakes and cookies. With my alloy mix of WW and a bit of lino, frosting does maybe make weights closer, but my size went to heck. I tried weighing bullets into batches and have came to the conclusion that it is not necessary until you get wayyyyyyyyyy on out there 400+?
I have my pot set now to what the alloy seems to like temp wise. When I start getting a few that are frosted, the pot is low and gaining to much heat, so I add, wait till it recovers and go again.
Rather than figuring weights, I look more at size and OAL of the CB's. Weighing was a PITA, then deciding how far apart to batch them made a real headache.
I did go through and weigh a few 30's a while back, they varied about 1 grain at the most. I figure if it ain't broke don't fix it.
Jeff

montana_charlie
05-03-2007, 12:28 PM
Weighing was a PITA, then deciding how far apart to batch them made a real headache.
If you are dealing with 'heavy' bullets, some of that PITA and headache can be mitigated by using an 'easy procedure'.

An Ohaus 10-10 (same as RCBS 10-10) beam-type scale is my only weighing device, so it gets used for all things...including powder, cases, water, and bullets.
Since each bullet gets a very critical visual inspection, it just takes a bit more time to get weighed. Any imperfection gets classified as an 'ugly' and goes in the scrap box.

After some trial and error, you find the 'center weight' for bullets from a particular mould, and set the scale to read 'zero' at that weight.
With the pointer looking at 'zero', there are five marks above and five below.

A bullet which puts the pointer at not more then two marks above zero, and not more than two marks below zero is sorted as my 'target weight' group...and gets a felt tip '0' on the base.

If the pointer goes higher than the second mark (above zero), but not off the scale, that goes in my 'heavy group', and gets a felt tip '+' on the base.

Those in the same range below zero are the 'lights', and get the base marked with a '-'.

They all get gently placed (nose down) in a plastic 100-round box made for .45 ACP ammo...so the base markings are visible at loading time.

I have never taken the time to find out exactly how much weight those divisions on the scale are worth. At one time, I assumed they were tenth-grain increments, but I'm (now) pretty sure that is incorrect. Probably more like half-grain.
Yeah, that would be a pretty coarse segregation for bullets in the 100-200 grain class, but it seems to be OK for the 500+ jobs.

Anything which causes the pointer to move beyond the ten-segment pointer scale is relegated to use as foulers or plinkers...but only if they are visually perfect.
I just won't mess with 'ugly' bullets...and that includes frost.
CM

BABore
05-03-2007, 01:16 PM
BA is right. If you want quality bullets, capable of fine accuracy, you need to keep tight control of temperature. Both the alloy and the mold. I cast from mainly 50/50 WW-Pb alloy and never, ever get frosty bullets. A well informed caster, 45 2.1, told me a couple years ago how to keep things stable.

Run the alloy between 650 and 750 F and look for the sprue to set up (color change) in approx. 3 seconds. Turn the mold in front of a small, high speed fan and cool the sprue for 3-4 seconds. Cut the sprue, dump the bullets, and hold the open mold in front of the fan for 3-4 seconds, then repeat the sequence. The time may have to be adjusted slightly depending on the mold, but the trick is, once your set, keep it steady. Good bullets are all about keeping everything the same. You can cool just the sprue plate all you want, but this does nothing to keep the mold temperture stable. Cooling the sprue plate on a wet rag is a PITA when you see the gunk that gets built up on it. I prefer to treat my molds as fine tools.

Using this technique I can easily keep weight variation in the +/- 0.2 gr range on bullets as heavy as 420 grains. This is on a per cavity basis. With certain molds I can get almost zero weight variation.

454PB
05-03-2007, 04:34 PM
Look closely at the picture. You can see that the edges of the shiny boolits are rounded and not fully filled like the frosty ones. Looks to me like the first boolits from a too cold mould.

dubber123
05-03-2007, 04:43 PM
454PB beat me to it, I read all the posts wondering if someone picked up on that, and I guess they did. I would take the frosty one with a few more seconds left before cutting the sprue. To me that would be a perfectly filled out bullet. The cracked off driving band problem would likely disappear with a few more seconds cooling time also.

montana_charlie
05-03-2007, 09:26 PM
Looking at Rusty's frosty trio, and disregarding the sprue divots...
I can't tell about the one on the right, because it's a little out of focus, but the base corner might be sharp. That corner is not sharp on the other two 'frostys', and the vertical one has dings and wrinkles in the driving bands.

I can't see the 'shiny' pair well enough to judge, but I don't think any of them would get far enough past a visual inspection to wind up being weighed.

However, as they are probably bullets intended for use in a revolver, they may be suitable for firing. A six inch group at fifty yards (from a handgun) is 'good shootin' for me, and they might be good enough to do that well.
CM

Bret4207
05-04-2007, 07:43 AM
Again, this is an art IMO. Beauty is in the eye of the beholder. I've produced boolits that were so sharp and perfect that I'd put them up against anyone elses. And I've produced a bunch that weren't quite so pretty, but shot better than the "good ones" . We all have our goals and they all vary. I can't see myself weighing every boolit. But I rarely shoot cast past 200 yards. Most is tree rat range or under 100 yards. A target shoot involved in long range work or a Hi Power match might have different needs. Not better or worse, just different.

686
05-04-2007, 09:54 AM
BA BORE i thought i was the only one that did that with a fan. works gtate for keeping every thing the same i am now using the magma 90 lb pot and have almost mo temp change. maybe 5de even when adding a 5lb ing. trying to find out how low i can and should go with my temp. for good fill out and speed.