I do not have a problem with the bases filling out. Nice sharp edges.

I made some casting experiments after cleaning the problem mould, Saeco 740, with Acetone and a brass wire brush. I also tried to touch up/clean out the vent lines with a scribe. Bullets were then casted with a 24/1 alloy at 825 F but were still not filling out completely at some of the outside band corners (look rounded). This is on one side of the bullet. I casted bullets from the same alloy, at the same temperature, with a Paul Jones mould casting a 429 gr bullet. The bands here filled out properly so there appears to be no issue with the alloy being contaminated.

From the pictures one can tell that the vent lines in the Saeco mould are not as wide and deep as the PJ mould. There are also fewer of these on the Saeco mould. I show the Saeco and PJ bullets side-by-side with a second Saeco bullet rotated to show how the other side is filled out properly.

To try and add more venting to the Saeco mould I will try next to deepen them. Can anyone suggest where I can obtain an engraving tool that would help do this?

Thanks much!

MartiniBelgian wrote on Mar 29^th, 2020 at 3:34pm:


I have heard this too, that vent lines may not be strictly necessary. The problem area interestingly, is basically where the mould halves come together at the back of the mould (towards the mould handles). Either the vent lines here are not venting sufficiently or the mould handles are drawing away heat from this area. I've compared the fit of the moulds to their handles on both the PJ mould and the Saeco mould and I do not see any significant differences that would sink more heat on one compared to the other. 

At this point I don't know what else to try, other than a new mould, possibly. Anyone know if BACO makes a #740 equivalent? 

A bit of frosting will not hurt a bit.
beltfed/arnie

Oh, and Indeed, any Zinc contamination is "death" on good bullets. It is more prevalent nowadays in the Clip On WW
than in the stick ons. 
I sort my bucket of COWW by trying to shave off  Every One of them with a utility razor knife. Steel wts. no cut. Zinc wts -the knife will chatter when trying to shave a bit off. Lead alloy ww the knife will shave off a sliver of alloy smoothly,easily, no chatter.   
Having had an incident a few yrs ago with melting down bank run COWW, resulted in a melt that was like slushy,
half melted ice cream. Trying that, BAD casting. I had to discard the alloy for fishing weights.
It is worth it for me to spend a bit of time making sure NO
Zinc COWW gets into my melts rather than having a 60 pound batch of melt Ruined.
beltfed/arnie
COWW

hepburnman wrote on Mar 29^th, 2020 at 4:45pm:


Try boiling the mold in soft water (without any minerals in it) for about 15 minutes. 

Did you try smoking it with a candle or wooden match?

[quote author=5E4C5A5D4C5B474C5B290 link=1584234373/45#45 dates=1585527343]I've had the same problem with every Saeco mold I have. Once properly vented as John and I pointed out, all cast excellent bullets. [/quote]
I just made an engraving tool by blunting the tip of a yellow retractable utility knife and engraved all the vent grooves in my saeco 740 mould. Some of these grooves were barely grooved. They're now all somewhat uniform. Next weekend I'll give the mould another try and see if things have improved.