Bottom Pour Questions

[Blacktail 8541]

Just started useing my rcbs pro melt today and have a few questions.

1. Should the flow of alloy be directly into the center of the sprue hole or hit the
edge?

2. Should the mould be up tight to the orfice or a little lower?

3. Higher or lower temp with 50/50 alloy?

4. What methods produce the most consistant Boolits for you?

[buck1]

Just started useing my rcbs pro melt today and have a few questions.

1. Should the flow of alloy be directly into the center of the sprue hole or hit the
edge?

2. Should the mould be up tight to the orfice or a little lower?

3. Higher or lower temp with 50/50 alloy?

4. What methods produce the most consistant Boolits for you?


As for my .02

I pour mostly in to the center, But not always.
Hold the mold away about a inch and you will get less air bubbles in the bullet.
I cast a little hotter than most, About 700F.
Every mold has a personality of it own and some tinkering is often needed.
Holding your mouth just right is the key!! ....Buck

[JohnH]

I'm with buck1 on this, typically I aim for a center hit, but as often, the stream hits the edge. I've not ever been able to tell any difference. I've not ever had success holding the mold against the spout. While that works with a ladle, it sure don't seem to with bottom pour. And holding about 1" low is about right. I've tried holding about 1/2" away, but again, can't seem to make any difference that shows up on the paper.

[MT Gianni]

Keep a note book as you will find some molds like different styles. Results are what we are after so experiment for good bullets. I had a mold that liked everything and a couple that I fought every time for a low reject rate. Gianni.

[Four Fingers of Death]

I have been using one for many years now and am very happy with it. I freehanded the moulds under the spout for many years, but later started using the guide rod with the two adjustable 'collars' that was the moulds are presented to the spout very consistently. I guess they wouldn't put it there unless there was a use for it. The most important thing I learnt with the Pro Melt and strangely enough I have never heard anyone else ever mention it is to keep the 'head' of lead consistent. What I mean by this is to keep the adjuster screw on the arm on top of the furnace which has the handle that you lift fitted to the bottom of it adjusted properly. Most people seem to set and forget this. This will be ok if you consistently keep the pot full. If you let the level drop, losen off the screw and this will keep the flow velocity constant. Great bit of gear, enjoy.

[Roudy]

I still use a Lyman pot that looks to be over 50 years old (just after electricity was invented!) and for years I've always held the mold about 1 inch away from the bottom spount and tried not to hit the sprue plate. Recently I started holding the sprue plate against the spout and found that there was no difference for me, in fact the bullets seemed a little more consistent and the sprue was very small.

I think Buck was right, it is most important how you hold your mouth! You might try your own experiment, cast 20-30 in different ways and weigh them to see which are more consistent and heaviest.

[carpetman]

When I cast .22 bullets(Lee pot) with a 58 grain RCBS mold if I hold the mold directly to the nipple,the sprue is just a bb size speck and doesn't release easily. If I cast that way I have to use something(I use a piece of coat hanger with a 90 degree bend tip)and pick it off. I can fill the mold with direct contact and then back it off from the nozzle and puddle a larger sprue and it will release easily. 6 to one half a dozen to the other. If I pour without direct contact,I'll get a fair number of rejects---partial bullet. At only 58 grains,there are 120.69 bullets per pound,so the pot empties very slow and making the larger sprue is not a problem. Now you may ask what do I do with the .69 bullet? Well,I can't tell you on here.

[Blacktail 8541]

The note book is a very good ideal for me as I keep one for my reload activities also. Pour spout position seems to be personal preferance so far with a small leaning to a distance of about an inch. No one has weighed in on perfered temps yet, except for buck1. Thanks much hope to here more.

[44man]

Roudy, what do you mean, your pot is ELECTRIC? Mine has a hand crank on it!

[lovedogs]

Blacktail... Give a look at www.n-ssa.org for helpful advice. A properly vented mould and correct casting procedure will usually work best if you hold the spout tight against the hole in the sprue plate. I open my flow valve enough to force the lead into the mould with the weight of the melted alloy and gently rock the mould as it fills. That way the alloy will squeeze out around the spout when the cavity is filled and will vent well, also. When full quickly shut your valve, then pull down off spout a hair and open valve briefly to top off sprue, thus filling out the base nicely. It takes a little practice. But once this method is mastered, you'll have good bullets with perfect bases, no voids, etc. If you can get the site I mentioned it's full of good advice. Lots of luck to you!

[Dale53]

I use bottom pour and have done so for since the days of the little Potter electric pot. I learned a long time ago that each mould was individual as to how it responded to casting. A notebook giving characteristics of each mould you use would be VERY helpful. I mostly "contact cast" but I have some moulds that work really well when held (rest the blocks on the rest supplied) up to an inch away from the spout. I also leave the adjustment screw loose and adjust it as the "head of metal" is reduced to keep the pressure nearly the same.

As the other poster, lovedogs, has mentioned, it is EXTREMELY important to leave as large a puddle of metal as possible on top of the sprue. This must be liquid, so that the molten metal can be pulled down into the bullet below it as the bullet cools. This is what helps to avoid air holes and bad bases. It also keeps the sprue plate hot - this retards the cooling rate of the sprue and helps maintain that liquid state for the few seconds needed.

One last thing - I have been using Rapine Mould Release for several years. I put it on top and bottom of the sprue plate and on top of the blocks. A very light coat on the faces of the blocks will help to keep splashes of lead from sticking to the block faces. If this happens and you don't notice it right away, the blocks are held apart and the bullet is larger in diameter. I, frankly, cannot tell where these "splashes" come from but they seem to happen from time to time (just tiny little bits of lead). I have ordered a supply of BullShop's "Bull Plate Sprue Lube" and am anxious to see how it will work - always looking for something "just a little better"... :razz:

The truth is, if you cast a lot and pay attention to what is happening you will come to a lot of these same conclusions, yourself. These forums sure have the ability of shortening the learning curve, tho' :razz:

Dale53

[Blacktail 8541]

Yes the forums tend to shorten the learning curve, and a person would have to be a little dense or full of himself to not take advantage of a pool of knowledge that is available. I have been getting pretty good boolits from the get go, just trying to get the weight tightly controled.