My most difficult mold

[Wayne Smith]

I have promised to post some illustrations of my most difficult to use mold and the results of using it wrong. In this case the mold is the Lyman 457122, the famous Gould Hollowpoint mold. It is a single cavity mold. I cast with a ladle.

I must also admit here that I did take some zinc-looking stuff off the top of the melt a melt prior to using this mold, but will say that this same melt cast the Group Buy .32 Keith normally and without problem.

This mold demands a very hot melt. I cast these boolits with the melt between 840 degrees and 900 degrees, measured by an electronic theremometer with the probe in the melt. With the melt at a lower temp I get rounded bases. It also demands that I pressure cast, with the mold turned to the ladle and the whole tipped up, then the ladel turned to leave lead on the sprue plate, otherwise I get bottoms that look like this:
CIMG1508.jpg

To me this rounding is unacceptable. This mold also requires me to do the Bruce B mold cooling, turning the mold and cooling the sprue plate on a wet towel. If I don't, I get a boolit that looks like this:
CIMG1509.jpg

Obviously, I opened the mold and knocked the boolit out before it cooled. Notice the frosting on the base of the boolit but none on the nose.

Finally, if I do it right, I get boolits that look like this:
CIMG1511.jpg

In doing this the lead is hanging off the ladle in sheets and it is hot, but the result is worth it.

Edit: I tried to follow the directions for an attachment, obviously it didn't work!

[geargnasher]

I know you've been doing this for a while, but check the obvious stuff. My first thought is those boolits look like they need some tin, and maybe do have some zinc contamination.

Barring that, if you have to cast that hot to get the base to fill out but the nose is still not frosting, odds are it's the mould temp, not alloy temp causing the problem. Too much metal/mass/heat-sink around the nose area compared to the driving band area. If you haven't already tried it, I would say dunk the forward edge of the mould (pin out, blocks tightly closed) into the melt for about 25 seconds without submerging the hp hole and see if that doesn't get the nose area to heat up. Once you get that part hot enough the heat should stabilize and you should be able to lower the pot temp to about 750*, provided your casting rhythm is rapid enough to keep mould and pin hot. As for the rounded bases, I use a bottom pour and pressure-cast when doing hollow points and I never have trouble forcing the bases to fill out with a sufficiently hot mould.

One other thing to look at if you haven't already is the vent lines in the top half of the mould. Lyman vent lines could use some work, especially on the single-cavity where they are longer than the 2 cavity and the air has longer to travel.

Or, you could let me borrow it for a while and I'll teach it to behave.........

Gear

[Wayne Smith]

I have dental tools. I have run the vent lines with such a tool, so if they are inadequate they need more than cleaning. Casting at close to 900 degrees and Bruce B'ing the sprue plate should have had the mold up to temp completely. I had over 60 of them when I quit - it was running quite well then as long as I cooled the sprue.

[John Boy]

Wayne, what is the Bhn of the alloy that you were using for these bullets?
Using a Bhn of 9.8 (close to 1:20 alloy) with the pot temperature at 720 degrees - completely filled out bullets with no flaws using the same mold

[shotman]

Kroil is all you need. It make a HP mold worth the time to mess with

[Buckshot]

.............Wayne, when attaching pictures pulled off your hard drive they will ALWAYS appear at the very bottom of your post, regardless where you stop and hit the "Manage Attachments" buttom.

Great pic's anyway, and it's simple to see which one you're talking about.

...............Buckshot

[Wayne Smith]

Guess I'm gonna have to learn how to put them on a pic host place!

DK BHN, but it's 50/50 with about 18" of 95/5 solder added to a 20lb pot.

[Echo]

I went out into the reloading lair and measured off 18" of Grainger 1/8" No-lead, then weighed it - less than 7/8 ounce (372 grains). So (if you use 1/8" solder) you basically didn't add any tin to a pot with 320 ounces of alloy. If the pot was only half full, you added less than 1/2% of tin. With the tin from the WW's, you might have had 1/2% - that is not enough.

If you only put 10 pounds of 50/50 in your pot, reel off 2 YARDS (or a little more) of solder and make a decent alloy.

[38-55]

Wayne Sir,
I've been casting that bullet for quite some time.. I find that my mold cast best with the softer alloys.. it likes almost pure lead.. I do preheat the nose pin by dipping it in the pot.. My experience mirrors your in that the mold like to be cast hot.. Best advice I can give ya in when things are going right keep casting til your hands feel like they are going to fall off.. It's a pain in the rear from time to time but that is one deer killing projectile out of a 45-70 over 27 gns of accurate 5744....
Hope this helps,
Stay safe
Calvin
PS I find that a 'medium grip' casts best.. if you hold the mold loosely it won't cast and if you grip it to tight it screws up.. go figure... it took my a bit of time to figure that one out..

[Springfield]

If the bases aren't filling out why would you want to cool them off via the Bruce B method? I cast a similar bullet sans HP and find that it is better to cast faster and turn down the temp. I run a soft alloy, 2 parts WW to 1 part pure with a bit of tin thrown to make it maybe 1% tin. I don't like wasting tin and usually find adding more doesn't overcome my bad casting technique.

[Wayne Smith]

I posted this more for an educational intrest for those who are new to casting and don't know what some molds require, or even that some are different than others.

Springfield, casting this hot I get full base fill out when I pressure cast, it just takes so darn long for the base to harden! I cool it to speed up the process, no other reason. A fan may do the same thing but it would cool the whole mold and the nose obviously doesn't need it.