Pressure casting

[Charlie Two Tracks]

I just tried pressure casting tonight. They produced very good boolits with sharp lines in the grooves. I kind of like that.

[shootinxd]

Been to dang hot to cast right now,but I am going to try that and see if the boolits come out better.How bout sum pics?

[leftiye]

You'll get voids. (Doesn't let air out of the sprue hole. Doesn't provide a liquid pool sprue for the solidifying boolit to draw from)

[noylj]

IF you mean sticking the pot's spout into the sprue hole and letting her rip, it works great. You leave the pot and mold in contact for several seconds. Produces very good bullets. No need for a large pool of molten lead on sprue and you have already passed through the time it was needed with a HUGE amount of molten lead for a pool. If lead is too cold, though, you can get a momentary frozen spout.
Only problem is if you ease up and then you get a squirt of molten lead heading somewhere.
I found that I was better off keeping about a 1/2" clearance between spout and sprue hole and just casting a nice big pool of molten lead. Much better than shooting a stream of lead at my shirt.

[HammerMTB]

I use the pressure pour method almost exclusively. I get better and more consistent boolits that way.
I find that the melt and spout must be fully up to temp. If I hurry it at all, as was said above, the spout freezes. PITA
I also find that the cadence is important. The very small sprue is enough, as long as your vents are all working. I found if you pull the mold too soon, you will get a pocket or void in the boolit base. Take a moment more and wait for the fill to happen and freeze.
Those who drop pour wait for the sprue to solidify. I wait hardly at all, if at all. There is also less sprue to deal with, so I refill the pot less often. It does take some time to figure out how to make it work with your setup. Right now I have WW+2% tin in the pot and it is casting some nice boos. I weighed about 80 just for drill and the weight variation was less than 1.5% in a 340 gr boolit.

[Mk42gunner]

I have one mold that requires pressure casting; an old Ideal 313445 95 grain SWC single cavity. The biggest problem with it is getting the small dot of lead out of the sprue plate, I have resorted to using a short piece of 12 ga copper wire that I wear like a ring to poke the sprue out with. It is a pain to cast this way with my Lee 4-20. The next time I cast with this mold I am going to try the 10 pound Lee pot, I realized sometime within the last week that you can actually see the spout on the smaller pot.

Of course this all depends on if I remember when I cast these the next time, I still have most of a pint of these small boolits left. A pint of 95gr 32 cal boolits is quite a few.


Robert

[Doby45]

I think I will try this when my 358477 gets back from Buckshot. Prolly will give me nicer fillout on the HP boolit.

[462]

I have a couple moulds that benefit from pressure casting. One mould, regardless of how much I played around with the sprue plate, would not drop boolits that didn't have rounded bases. The other benificiary is a bevel base mould.

After the cavities are filled, I pour a sprue just large enough to cover their holes, then cut it when it's cooled. I've found that this eliminates the small pieces of sprue that had a tendency to remain in the holes. Never had a problem with the Lee 10-pound spout freezing.

For the moulds that require it, I find pressure casting a simple and efficient method.

[geargnasher]

I have only one mould that gets the pressure cast treatment anymore, that's the Lyman Devastator .45. It has a flat base and a huge spud, and very thin walls around the HP nose. To get good fillout I have to cast hot, fast, and use pressure. I do get some whiskers if I use 2% Sn, but I just ignore them completely because by the time they are sized, lubed, and loaded, they have been handled enough to knock them off.

The main reason I try to avoid pressure casting is getting bits of lead foil stuck to the mould block faces, usually from a whisker or two popping out of a vent line and getting caught between the blocks when I close them. This creates a snowball effect with leakage and buildup, and is a pain to remove from hot blocks without damaging the edges of the cavities. If I have a mould that is cantankerous with fillout I either sell it or ladle pour. Ladling solves the other problem that sometimes happens with the pressure casting process: Inconsistent head pressure as the pot level changes. I "pressure cast" with the ladle, just the right amount of head pressure, especially with long, skinny rifle boolits.

Gear

[JIMinPHX]

In my experience, temperature, alloy, mold venting, & pressure casting all need to be kept in balance to get good boolits. Too much of too many will give you get fins & whiskers. Too little & you get wrinkles & rounded bases. Sometimes more of one will cover for the lack of another. For instance, molds with inadequate venting often cast better with high heat & pressure casting. Molds with lots of venting usually will run well at lower temperatures with just a sprue puddle.

[Charlie Two Tracks]

I haven't the slightest idea on why the boolits are looking better. I haven't been doing this long enough. I just know that for whatever reason, they look really good. I hold the mould up to the spout real tight, count to three, cut the sprue right away and there there they are! For now, that will work for me.

[Bret4207]

IME some moulds want contact pressure casting, some want a drop type casting, some require a ladle and some don't care. Probably it's a combination of me and the moulds. No one method works for me. Remain flexible in your thinking, it helps.

[Shuz]

In my experience, temperature, alloy, mold venting, & pressure casting all need to be kept in balance to get good boolits. Too much of too many will give you get fins & whiskers. Too little & you get wrinkles & rounded bases. Sometimes more of one will cover for the lack of another. For instance, molds with inadequate venting often cast better with high heat & pressure casting. Molds with lots of venting usually will run well at lower temperatures with just a sprue puddle.

Well said,Jim!

[fredj338]

I just tried pressure casting tonight. They produced very good boolits with sharp lines in the grooves. I kind of like that.

Pretty much how I do all my casting except on my Magma. Works very well for LHP.

[casterofboolits]

All my moulds work fine and I get full fillout with bottom pour pots. Lyman, Saeco, H&G, Lachmiller and lee. Never a problem.

[excess650]

Most of my molds cast well via pressure casting with a Lyman ladle. I have a few that don't seem to like to have the ladle in contact with the sprue plate, so I oblige them.

My 20# Lyman and 20# Lee bottom pour pots have both been plugged, and I have (1) RCBS ladle (handle is too long and I don't care for the fin on the bottom) a normal Lyman ladle, and another Lyman that has had the spout drilled oversize. I use the latter almost exclusively when casting bullets. The Rowell bottom pour ladles are too large for use in the Lee and Lyman pots, so only get used when making alloy in the dutch oven.

My RCBS may get the fin ground off the bottom and the handle shortened as it seems advantageous at times to have its extra capacity.


IME some moulds want contact pressure casting, some want a drop type casting, some require a ladle and some don't care. Probably it's a combination of me and the moulds. No one method works for me. Remain flexible in your thinking, it helps.

[GLynn41]

i guess because I use an RCBS dipper or Lyman dipper- all of mine are "pressure" and yeah it has been to hot to shoot or cast-- no problems with any of my small group of molds-except my Mountain Mold likes to have a pour --- and wants the larger RCBS dipper-- my 410459 HP by Buckshot works fine with the Lyman dipper - but mostly I use the RCBS-- I have used it since the late ??? do not remember now any way the reason I mentioned it is becasue from tapping it at times to get stuck slag out it is flat one side :) still works

[dudel]

I used to do that; but getting the tiny sprues out was a bit of a pain. Strangely, I had more voids when I pressure casted. I suspect air was not escaping quickly enough. I also found it a bit more tireing having to keep the mould pressed up to the spout.

I did incorporate some cleats on the bench to keep the Lee pot from tipping. Even though I don't pressure cast any more, I did keep the cleats to keep the pot locked down.

[Suo Gan]

I can never get the ones I pressure cast to shoot worth a hoot...they sure look good on the outside though. I assume they have internal air pockets that are larger than normal.