Moderate success with casting big bullets

[bdoyle]

I haven't cast any 500 grainers (457125) in a while and normally would use a rowell ladle. Well I decided to try my RCBS bottom pour pot. It has a pretty decent flow rate so I thoght I would try it. I started about an inch below the spout and got the normal oxidation on the nose of the bullet and weights were varied.(510 to 518gr) I tried up against the spout and got a clean bullet but weights were very light. Dropped down to about 1/4 inch and things were looking better but still 30%-40% reject. I adjusted the flow rate to a fast flow but not splashing out of the mould. Started to do a 3 count after the mould was full and things really settled down. It was messy but the reject rate was around 10% or less and weights were running 517.8 to 518.5 with majority at 518.3 Oxidation was minimal - maybe a haze on one side but no holes or pits. Just had to do 100 for a friend(who supplies lead and such). Pretty happy with the results with a bottom pour. I was playing with the temp control to try and stay at 800 deg using 20:1 alloy.

Brian

[Dale53]

Brian;
I am a bottom pour man. I have cast thousands of .40 and .45 caliber bullets (up to 550 grains - not counting heavy musket bullets) with excellent results. Some of my good friends prefer dipper casting. They are still my friends:mrgreen:.

You can do good work either way. There is both ART and SCIENCE to making good bullets. Each mould can be a law unto itself. Some bullets I "contact cast" and some I "drop cast" but ALL from the bottom spout. Just use the method that works with the particular mould in use.

Dale53

[BruceB]

I'm blessed if I know how you get such a wide variation. What is the temperature of the melt? Whatever it is, if it's less than absolute MAXIMUM in your pot, turn it up to the limit and go for it.

There is a very strange (to me) reluctance to CRANK UP THE HEAT when casting. There are too many old wives' tales about "bad" frosty bullets (BS) , about "burning the tin out of the alloy" (BS) and a number of other things which contribute to this reluctance..

In honesty, watching casters discuss the merits of plus- or minus- 25 or 50 degrees is like watching someone trying to decide which is the LIGHTEST caliber which will barely suffice to kill his deer, not over 150 pounds, not over 180 yards, and broadside. NIT PICKING, in other words.

I've written a lot about casting fast and hot. You know why??? IT WORKS! On reading the above posts, I went to my bench for some test-weighing. All the bullets weighed below are straight wheelweights, cast at 870 degrees from my RCBS bottom-pour.

I grabbed a handful out of a pile of newly-cast 416-350s, from a single cavity RCBS mould. WITHOUT ANY INSPECTION WHATEVER, just a random handful of 18 newly-cast bullets, the extreme spread was 0.8 grains on an average weight of 359.

Next was a handful of 15 LEE .45- 405 hollow bases, sized and lubed. We all know that casting HBs can be problematical, but, INCLUDING any variation in lube weight, the fifteen bullets showed a maximum weight spread of just 1.2 grains, and averaged right at 400 grains.

The heaviest ones I happen to have on hand were Lyman's 457406, sized, lubed and gaschecked, and averaging very close to 500.0 grains in that condition. Maximum spread is 1.6 grains over 19 bullets, including the variations introduced by the lube and the gaschecks.

I reject bullets for flaws which I can see but which do NOT always seem to be "weigh-able". That is, I reject for flaws which my scale doesn't recognize. I can't imagine what sort of flaw shows an eight-grain spread, beyond serious malformation or invisible voids. Neither is a problem when I cast the way I do. The later results quoted are much better, and what is the concern about "oxidation"? If appearance is important, a few seconds on the loaded round with steel wool will knock yer socks off for shine!

Yep, I'm an opinionated old b-----d, but I've paid my dues and know how it CAN be done successfully, at least in one way.

[sundog]

I'm with Bruce. Crank the heat up to max. Only time I back off is when I have to wait too long to cut a sprue or start to get some whiskering. Maybe I ought to take up the wet rag method. Naw. I like the way I do it. But the pot runs wide open. sundog

[Dale53]

Just keep in mind that lead vaporizes at 900 degrees. Breathing lead fumes is a definite MINUS! Most lead pots will NOT get that hot but some will. Just keep the melt under 900 degrees and all should be well.

FWIW
Dale53

[David R]

I always start at full throttle,then as the mold heats up, and after I dump back the few first few, I can back the heat down a little so I can cast at my preferred rate (pretty fast).

Works for me.
David

[bdoyle]

While I agree with all that was said, until you cast with the lyman 457125 I'll reserve my right to say this mould is different beast. Big bullet, small block, no mass to hold the heat evenly. I'm going to have to try the saeco version (larger blocks) but the lyman just fits so well.

Brian

[BruceB]

Well, my 457406 is also an older single-cavity mould, fitting the Lyman "SMALL" handles, and it weighs almost as much as the 125. I'm not sure why I bought this design, but it sure does shoot well in my Shiloh .45-70. I don't believe the gascheck is really necessary, but....the mould was there, I reckon, and I bought it.

I still have a lot of load work to do with this one (and all the other .45 moulds on hand, for that matter!). I'm leaning to "original" .45-70 velocities, mostly below about 1450 fps. They're pleasant to shoot at that speed.

[montana_charlie]

Just keep in mind that lead vaporizes at 900 degrees. Breathing lead fumes is a definite MINUS!
Dale53,
I am certainly no chemist, and the 'fume breathing' thing has always been in the back of my mind when trying to peer into my pot to see if anything is starting to melt.
Your statement that vaporization occurs at 900 degrees was so definitive, I was (finally) prodded into actually looking for corroborating information.

What I found appears to disagree with you.

Googling for the term "Pb", I find that lead's
Heat of vaporization [is] kJ/mol 177 .7

That was Greek to me so I searched on that term and found that a material will vaporize at it's 'boiling point'...and the boiling point of lead is 2023 Kelvin - or 3181.7 F.

From other reading (in the past) I think the 'fumes' we need to be careful of are actually the tiny airborne particles of lead sulfate which float unseen around the area. I believe that yellowish powder that forms on the inside of our melters is that substance, and wire brushing the interior (for instance) throws it up where we can inhale it.

Some describe their cleaning method as 'boiling and scraping', and I suspect that will keep the inhalation hazard to a minimum as long as the material is disposed of while still wet.

These are all suppositions on my part.
If anybody knows 'the truth', (or even that Dale53 is actually correct) we can all benefit from hearing it...

That same yellow crud was forming on my Lyman dipper. I try to stand out in the wind when scrubbing it with a toothbrush-shaped wire brush. I also find myself holding my breath as I scrub.

Spraying the cleaned dipper with the same aerosol graphite that I use on my moulds seems to prevent the formation of the crud.
I plan to try it on my pot...next time I get it really clean.
CM

[Dale53]

montana charlie;
It appears that I may have been laboring under a false impression. I KNOW that I read that someplace, in fact more than one place, in the past but when I tried to check it out after someone else PM'ed me, I find numbers all over the place. I am NOT a metallurgist, so I have apparently have been wrong for a number of years.

At any rate, I don't think we have much to gain by running the bullet metal extremely hot (over 850 degrees) so I'll just keep on casting at as low a temperature as I can. Dennins Marshall, a metallurgist, states that tin starts burning out pretty quickly above 750 degrees, so that is reason enough for me.

I am now sorry that I cried "wolf" but I guess "better safe than sorry"...

You ARE correct to be wary of lead oxide. That "dirt" that we skim off the top of molten lead carries all kinds of nasty stuff. I am pretty dern careful not to stir up any dust and avoid breathing this.

Dale53

[montana_charlie]

Dang it, Dale!
Just when (in another thread) I got convinced that I was worrying too much about my precious tin, you have to go and quote a metallurgist as saying...

Dennins Marshall, a metallurgist, states that tin starts burning out pretty quickly above 750 degrees, so that is reason enough for me.
That is after an earlier post in this thread where BruceB said...

There is a very strange (to me) reluctance to CRANK UP THE HEAT when casting. There are too many old wives' tales about ... about "burning the tin out of the alloy" (BS) and a number of other things which contribute to this reluctance.
Hmm...Deuling Banjos? Wherein lies our 'deliverance'?

Offering no comment regarding alternate life styles, I find myself wondering if Dennis(sp) Marshall - in addition to being a metallurgist - is an old wife...!?!?
CM

[Bass Ackward]

"Burning" off tin does start about 750 degrees. Especially when the mix is agitated. A concern when Lyman #2 was an important standard. Considering that most folks don't run high percentage tin mixes, little tin is lost as the percentage is decreased at those temps when dispensed from a bottom pour. Lino is another common mix that is vulnerable. I have no idea exactly where the cutoff is, but my 2% mix is fairly safe up to 800 degrees. Just bear in mind that in an hour or so, it is consumed into something else. So my point is that time would also be a variable to consider.

[Dale53]

I am going to "double post" here, since this is where the thread started:

BruceB:

Since I am the one who made the statement on another thread, I will defend it. As I have stated before, I am NOT a metallurgist, but I was quoting Dennis Marshall, who IS a mettalurgist. The difference between my comments and your experiment is:

>>>We then filled EXACTLY that one-inch of volume with industrial powdered graphite, to keep the mix from oxidizing unnecessarily by air exposure.>>>

"In as little as 30 minutes, the majority of tin is drossed off at 1050 degrees". This is page 48, column two in the Lyman Cast Bullet Handbook, third edition (Dennis Marshall's article on lead alloys).

He explained how to control that with a deep film of Borax over the melt. You used graphite which did the same thing.

I essentially stand by what I said. I also believe you. Having a barrier to oxydation is the key in this particular case.

Dale53