Need help with bullet quality in a Bottom Pour pot

[Dimner]

First time bottom pour pot owner here. Also kinda frustrated.

For the past 1.5 months I have tried dialing in the bullet quality of my RCBS pro melt 2. I dont think it's an issue with the pot, I think it's an issue with my "settings" for lack of a better term.

I'm casting a 73 grain 227 bullet with a 6 cavity brass mold. (I have tried 2 other 22cal molds, one brass one aluminum, all with the same problems)

When I bottom pour I get anywhere from 50-75% rejects. I'm pretty picky about my rejects. The most common rejects are based on the bearing band fillout (rounded in places or beveled) and little wrinkles in the lube groove nearest to where the mold closes. With a ladle pour I can get down to 10% rejects if I have my rhythm going really well.

My process so far for trying out new settings is to adjust my mold guide, flow rate, and/or temperature on the PM2 and then cast 100 bullets with the bottom pour pot then 100 with the ladle out of the top of my PM2. With 100 225 bullets, the level of lead in the pot doesn't change much, but I get a decent sample size. Then after 100 of ladle pour, I go back to the bottom pour for about 50 bullets to make sure I was getting the same results as when I began.

So it's the same alloy (cww+2%) and same temp for the two groups of 100 bullets. The alloy is super clean.

I've tried, casting fast, casting slow, Temps as low as 690, as high as 750. The mold guide about .650 inches from the spout down to 1
25 from the spout.

With a bottom pour, there is something about the way the lead is delivered to each cavity that are causing these issues. I'm at my wits end of what to do.

For the life of me I cannot find the sweet spot to get this bottom pour pot to cast consistent quality. I'd be fine with 25% rejects, in an ideal world 15% or less would be nice. The problem with my current results is that there is no time or effort saved when I have to recast a bunch more bullets.

I have read many archive posts on the subject of ladle pour vs bottom pour. But what I do not see is an explanation of the settings everyone is using to get excellent quality bullets from a bottom pour pot.

What are your secrets? How can I close the gap with my bottom pour quality to get it closer to a ladle pour.

[Mike W1]

I've never cast anything that small so take this FWIW. Noticed one mold is brass and they apparently are harder to get up to and keep at casting temperature. I'd suggest a hot plate for that as a remedy for one thing. I'd also lower the gap between spout and mold to about 1/4". Everyone seems to differ but I've always had my best results pouring directly into the sprue hole. Others let it run in and some have it swirl in. Either of which I "think" requires the sprue plate to be much hotter. Those latter 2 seem to require a much larger sprue than my way does. The Art & Science forum has some guys that pour 22's and could be of some real help to you. Also might try the CBA site.

Even a 15% reject rate is pretty high. I only do pistol anymore and seldom have to reject anything but mine aren't the little itty bitty ones that are a lot trickier either. I'm sure one fellow over there bottom pours match quality 22's.

[Conditor22]

Preheat the mold on a hotplate set to 400°

Pressure pouring on a bottom pour pot is like ladle pouring, Hold moth mold tight to the spout, pour lead, and keep pouring for a second when you lower the mold from the spout. This is a way to heat up a mold at the beginning of a casting session. When the mold gets hot you can go to the regular bottom pouring with the top of the mold 1/4 - 1/2 inch from the spout.

adjust the flow of the lead to where it is fast but not too fast that you can't control the pour.

leave a quarter size sprue puddle on top of each cavity.

I like to "purge" the spout (squirt a little into the catch basin underneath to remove any cooler lead in the spout before each pour

[John Boy]

No fill out = mold too cold and with a multi cavity, have to keep the whole mold at temp. Plus, a 5 chondrites pour for each cavity and a large sprue puddle across the whole top of the mold

[Mal Paso]

Might put the mold back on the hotplate while the sprues freeze to keep the temp up.

[Kylongrifle32]

I prefer to ladle pour most of my boolits. Using a cast iron pot and coleman gas stove. This set up not having a temp control I just keep raising the fire till they fill out better.
I cast two different heavy 225 boolits a 5 cavity 73grain and a 4 cavity 79 grain and when I'm using my old lyman pot the temp is set upwards to 825 for these. Its usually at 750 for other boolits with my alloy.
When I'm using the bottom pour on these mold I also don't start and stop the pour at each cavity. I open the spout and hold it open till all the cavities are filled then stop the flow. Fill the first cavity then move the mold to the next hole leaving one long continuous puddle on top of the spru plate. This helps to keep it heated up more. And a good fast pace helps.

Also what is the air temp where you are working. I get a lot more keeper when it's 90 degrees out versus 40 degrees that's why I do most of my supply of 225 boolits in the summer time. Its hotter out so the molds stay hotter.

Don't be afraid to turn the temp up till you start getting frosted boolits. If this happen you can adjust the temp back down our slow your pace. Frosted Boolit should be well filled out and shoot just fine.

[Bazoo]

Mould temp, but also sprue size makes a difference here. Ladle casting I leave as large a sprue as I can without it running off the mould or into an adjacent cavity. If it runs, I'll get slightly rounded bands. If I have a small sprue with a small bullet, fillout isn't as good.

[Mk42gunner]

Long narrow boolits seem to be the bane of bottom pour casting, which to my mind a 73 grain .227 diameter pretty much defines.

I haven't cast any .22's that long, so this is primarily guesswork. Try setting your mold guide to about ¼" clearance, it could be the alloy is cooling just enough to cause problems with fillout.

What I have done with all my bottom pour pots is to adjust them to where they work with most of my molds, then leave them alone. Some molds just seem to work better by ladle filling, I have had some that work better by pressure filling from a bottom pour though.

Good Luck,

Robert

[Dimner]

I'll try to respond to many comments here, but first off thank you to everyone for your help and suggestions.

I should start off and confirm that I always use a hotplate. I never start a casting session without having heated up my mold first. Settings are dialed in on the hotplate to I always get frosty bullets on the first pour.

And as for mold temp, I'm getting frosty bullets by both bottom pouring and ladle pouring. So I know for sure we are in the frosty bullet range.

I have cast as high as 750-760 when running the test of both 100 ladle bullets and one hundred bottom pour. Are we saying by nature of just bottom pouring I should crank to somewhere close to 800?

I'm already doing big sprues when bottom pouring since I did notice that visual difference between the two methods. However, I have not gotten closer than about 5/8th of an inch to the nozzle.

I have tried filling from front to back then back to front. For some reason filling the front cavity reduces the rejects by a little. I'm always continously pouring. No starting and stopping the flow.

I do cast directly on center line of the cavities. I had not heard of the 'swirl' technique. Did some archives searching and I'm going to give that a try.

Tonight or tomorrow morning I'll give a shot at a swirl super close to the nozzle.

Can someone also give a little more detail as to what "pressure casting" is with a bottom pour pot?

[Winger Ed.]

Can someone also give a little more detail as to what "pressure casting" is with a bottom pour pot?

Move the guide out of the way.
Hold the sprue hole on/up against the bottom of the pour spout.

(Note how well they fit? Now ya know why the nozzle and sprue holes are shaped like they are)

Fill both cavities, let the mold down and pour a sprue.
Wear big gloves. You will get a little bit of splatter. It bounces up too.
It doesn't work well if the mold isn't hot enough.

[Dusty Bannister]

With pressure casting, you place the sprue plate directly against the nozzle on the bottom of the pot. This naturally requires a start and stop of the flow.

If you do a "running bead" type of pour, you are allowing the hot alloy to flow across the sprue plate and it is deflected across the hole, and might be blocking the air venting from the cavity. I do the start and stop, move to the next and repeat. I also start from the farthest hole and tilt it slightly lower so that over flow will flow away from the next cavity. If you are only 1/4" from the plate, you might get a tall sprue button and then have to lower the mold rest to remove the mold from under the nozzle. I like perhaps 3/8" or whatever height allows clearance after the sprue puddle becomes solid. I usually cast at about 720 Degrees and my shed is not heated so I usually do not work in temps of less than 40 degrees. Especially with the small caliber bullets. Adding alloy to the mold is adding heat and small bullets do not add enough heat on a cold day.

Some sprue holes are a little on the large size and others can be smaller. The smaller the sprue hole, the nicer the bullet base can be and easier to cut the sprue. But that can cut down the flow into the mold. Compare the sprue plate holes with other molds and see if that could be restricting the flow and allowing the puddle too much time to cool before the mold is filled. Good luck, it will all come together with time and experience.

[Edward]

I can tell you but you will not like it , compression casting with a ladle /single cavity . It is nothing more than keep the ladle nipple mated to your mold and count to 10 . I said you would not like it but you will get 100 % fill with bases that would cut you and weights consistant with virtually no rejects . I do it for shooting long and can"t afford rejects as they waste powder and lead ,not brass (I shoot muzzle loaders) and single cavity is the only way to compression cast .A full ladle with the nipple pushed into the mold ,count to 10 and wait 5 before dumping sounds slow but it goes quick with practice .Try it and you will like it/Ed

[Dimner]

Sorry I also forgot to mention I'm casting at a climate controlled 67 degrees.

[jim147]

I've never used a mold guide but have almost always bottom poured. It's a feel and learn thing to know how close to the spout you need to be depending on the mold, temps and alloy.

[KCcactus]

With pressure casting, you place the sprue plate directly against the nozzle on the bottom of the pot. This naturally requires a start and stop of the flow.

That's the only way I can get my .22 molds to fill out. I don't add additional lead on top after the cavities are full. You can try it with and without extra sprue and see which works for you.

[Agarbers]

I have a RCBS Pro Melt II. If I run it less than 820 degrees, I don't get good bullets. I don't think the temperature controller is accurate.

[TjB101]

As others have mentioned ... mold temp. When I cast for .224 it is a pain ... I gotta move fast and keep the mold hot. When casting for 45-70 I can take a coffee break and still get a good cast.

[Burnt Fingers]

Take a butane lighter and lightly smoke the mold cavities.

[country gent]

While the alloy is in the pot they are all perfect its when you pour them in the mould the problems occur.

Try preheating the mould on a hot plate nit just to a certain temp but to temp and then 15-20 mins to normalize thru Then pour as large a sprue as possible. shield the casting area from drafts and breezes. Theres not a lot of mass in these bullets to keep the blocks hot.

Also check the vent lines and clean blocks well. Everything has to be right when casting these smaller bullets in blocks with more mass than the bullets have.

[Dimner]

What I don't understand about all this is why is my mold temperature perfect when ladle pouring, but not perfect when using the exact same variables (including mold temp) with a bottom pour.

It's just strange.

I wonder if some one could make a bottom pour spout that didn't pour straight down, but poured more on an angle to simulate the geometry of the ladle pour. As in a spout that delivered the alloy on a 45 degree angle or something like that.


But I still need to try some other things first. Mainly the sprue touching nozzle pressure cast technique

[ShooterAZ]

Brass molds are a real heat sink, much more so than aluminum or even iron. Even though you may have pre-heated your mold on a hot plate, the small 22 caliber boolits don't carry much heat with them to the mold as you cast. Think of it as pouring heat into the mold. As you cast, you may be losing a small bit of temperature each time you do a pour. Step up the cadence and pour large sprue even if it overflows is what I would try first. Just have a pan or something underneath to catch it. Increase the alloy temp as necessary to keep the mold hot enough. It's a balance, and you'll eventually find it.

[Mk42gunner]

[QUOTE=Dimner;5116531]... I'm always continously pouring. No starting and stopping the flow. ...

QUOTE]
As I'm sitting here running my casting technique through my head; it seems like I work the lever on each hole, not a continuous stream for the whole mold. I do go back and connect the sprue into one piece after all cavities are filled though.

This is the way I do everything from two four or six cavity molds.

Try it, it may help.

Robert

[jim147]

I getting kinda slow. Let's start over.

Going back to the OP. Same pot same lead same temp can you cast 100 with a ladle and have 10 bad ones and while everything is same temp do 100 with the spout and have 50 bad ones?

[popper]

Good cast depends on getting the air out and the alloy in and remaining liquid for fill out. Pressure/ladel casting just keeps the alloy hot in the hole. Wrinkles are from gas that can't get out. Rounded bands cooling too fast. You have enough tin. Try just one hole vary stuff till it's ok.

[rockrat]

I heat my moulds on a hot plate, then put the bottom of one end of the mould in the hot lead for 1 min. at the most. Pull it out and wipe the end off and give it about 15 sec. to even the heat out then pour with the sprue plate about 3/8" under the spout. I use a thermometer to make sure my alloy is around 710-715 degrees.

[Dusty Bannister]

When ladle casting, are you using a lyman or RCBS ladle or a spoon? If a side pour ladle, are you mating the ladle into the sprue hole?

When bottom pouring, is it free flow or have you adjusted the flow to reduce the force of filling the mold?

[popper]

Thee is no 'pressure' casting - don't know who thought up that term. Only pressure added is weight of the ladle against the plate - not on the alloy. It does add HEAT to the plate and alloy doesn't cool in the 1-1/2" drop. IMHO your sprue plate is cold and with the small hole you can't get hot alloy into the cavity fast enough.

[Dusty Bannister]

I do not know what else to call it if not "pressure casting". I place the hot nozzle against the sprue plate cavity (some heat from the nozzle transfers to the plate), open the valve to allow the weight of the melted alloy flow into the mold cavity and while that alloy is still fluid, remove the mold from the bottom of the nozzle and let it form a sprue puddle while the valve is still open to allow the alloy to flow.

I guess I would compare the principal as if using a volumetric powder measure and finding that the full column of powder in the plastic tube drops a heavier charge than the same measurement setting and a nearly empty plastic tube.

[Mike W1]

Thee is no 'pressure' casting - don't know who thought up that term. Only pressure added is weight of the ladle against the plate - not on the alloy. It does add HEAT to the plate and alloy doesn't cool in the 1-1/2" drop. IMHO your sprue plate is cold and with the small hole you can't get hot alloy into the cavity fast enough.

Believe I got into a discussion about "pressure casting" on some forum or another once. I didn't convince whoever nor did they change my opinion about the term either. Think you're of my school on this one!

[jim147]

It's called head pressure. Think a 55 gallon drum full of water trying to run your sink. Would you want it on the ground or on your roof?

A full pot will add more pressure than a half full pot.

[country gent]

Look at the 2 streams the one from the ladle and then the bottom pour. the ladle is larger and fills the cavity quicker will its all still molten the smaller stream may be starting to solidify before its full.

[gwpercle]

I never could get the quality of boolits I wanted with a bottom pour pot ... I tried for years , I could cast a lot of half-fast boolits but I want perfect boolits .
I gave the bottom feeder away to a fellow member , retired my cast iron pot and old (1967) Lyman dipper for a Lee Magnum Melter , 20 lbs. capacity, and a new long handled Lyman dipper .
Pressure Casting perfect boolits beats half-fast bottom pour casting Seven Ways to Sunday .
Gary

[JWFilips]

I'm not reading through all the answers here & I'm sure they are all good suggestions. I'm just going to add my experiences with small caliber gang moulds. I have been cast quite a long time and I know I hate Brass moulds. I do not have the patience for all of their idiosyncrasies
Life it too short and I think other mould materials cast as good. That said:
My buddy bought a NOE 5 cavity .25 caliber 63 gain mould and asked me to cast bullets for him.....Man I felt like an amateur again. I could not get that mould work to save my life. I even wrote Al from NOE a few times Thinking the mould was bad even though I checked it out under high magnification and it looked perfect! Finally Al said to run the mold "hot and fast" With a higher alloy temp.
Now The highest I run my melt is 725 deg......That was the problem I boosted the temp to 760-770 deg Poured as fast as I can and cut the sprews as so as i say the alloy harden! Way different than I normally cast BANG! perfect bullets!
So on that mould I marked a note with all the particulars on how that one had to be run.
The moral here is "sometimes you need to break the rules to cast stubborn bullets"
FWIW

[GregLaROCHE]

If you are getting good boolits from a ladle, the most likely variable to change is the flow rate. Run it as fast as you can keep up with it. You can pressure pour from a bottom pour pot, but shouldn’t necessarily have to to get good boolits.

[Old Caster]

I will always pressure pour from a bottom pour pot if I can and the limiting factor is whether the mold can handle it. Some of the cheaper molds don't fit real well and i will wind up with fins when I do it. Pressure pouring is complicated because there are a lot of factors involved. If your pot is full all the way to the top you will have a hard time keeping the mold and pot connection from squirting out around the sprue plate but it will give the most likely chance of a perfect bullet except for one problem which you don't get with a ladle. When pouring with a ladle, the channel that comes out for the pour won't get crud in it because the ladle is constantly whacked around to keep it clean. When the pour constantly goes through the bottom pour spout crud builds up ,which is why they drip, and some of it will come loose occasionally and into the mold and cause a bad bullet with out you knowing it except sometimes it will be right in the base where you can see it. When people are using a conventional system where they just pour into the mold, while they are pouring, the dirt will go up into the sprue and keep this from happening very often. Consequently it is necessary to keep your level rather low at around two inches. This makes the lead go in slower whereas the dirt can make it in the sprue also but causes problems like spout freeze. Next is temperature like has been mentioned several times and the smaller the bullet the harder it is to keep up the speed but if you made it with a ladle the bottom pour will too if you get everything right. Another problem is that when your lead level is only 2 inches deep, it is harder to add lead without putting it in liquid because you will constantly have to wait for it to liquefy and mess up your cadence, Making the lead hotter can help and the only problem with lead too hot is having to wait too long to open up the mold and taking a long time. I have a second 20 pound pot next to my bottom pour and add with a dipper to keep things going smoothly. Each mold I do this with makes me do different things regarding timing and temperature and you will have to take time getting this to work smoothly. Way more of a pain to bottom pour but the bullet perfection is worth it depending what you are going to shoot with the bullets and if you want the best accuracy or are just blasting.

[LenH]

I have never cast with a brass mold but the transition to a smaller bullet was a new learning. I mainly cast big .45 bullets and it is easy as can be.

When I started casting for .30 cal it was a new learning experience. I had to run the melt up to 750 and cast a bit faster and get the mold rocket hot. I also
adjusted the flow of the bottom pour.

[2005f22c]

Could it be your lead alloy? I was using an alloy of unknown composition that would not fill out unless the pot temp was 825 degrees, and even then it wasn't great. I added some "super hard" 30/70 lead antimony to it (to make it harder) and it actually started bottom pouring much, much better to the point where I was able to lower the temp down to 725 and it still filled out molds nicely.

[rbuck351]

I like slightly frosted boolits. I pour a lot of 37gr 22 cal boolits and run at about 825 degrees. I haven't used brass molds, just aluminum and iron. I have a few molds that don't fill well but if I hold the mold against the bottom pour spout they fill so well they fin. If I get as much as 10% rejects I turn the heat up and/or pressure pour. I have never been able to ladle pour with any real success.

[Duckiller]

You are a ladle caster. Accecpt it. I am a bottom pour caster. I have NEVER cast a shootable boolit with a ladle. Be happy with your ladle poured boolits and forget bottom pour.