Rounded edges?

[Jumbopanda]

I'm finding a few bullets here and there that have rounded edges on the lube bands instead of sharp ones, and I can't figure out why. Maybe 50% of my latest batch of Lee .501 440gr bullets had this problem. I use the exact same alloy (linotype), temperature, and casting habits that I use when I cast Lee .452 300gr bullets and I don't have this problem. I inspected the .501 mold and didn't see any defects in it. I can't figure out what's wrong. Do you guys think the rounded edges will hurt accuracy much?

[sagacious]

If only 50% showed the problem of rounded bases/edges, then the error likely lies with the pourer, and not the mold.

Large molds can vary wildly in temperature while pouring, especially if one is busy studying the rounded bases on the poured bullets, and the casting session is intermittently interrupted. Poor fill-out should not happen with linotype. Try to keep your pouring routine at a steady and regular pace. The pouring routine/pace that works well for one mold may not work at all well for another mold.

Try to keep your mold and lead at a constant temperature. That's not always easy, and requires some experience and close attention. When you add an ingot to the melt, your lead temp will decrease, and combined with the mold cool-down while waiting for the lead to melt, both mold and lead temp will vary. Other factors can cause temp variations too.

Pouring consistent bullets is an excercise in keeping all the variables consisent. The rounded edges may or may not affect the accuracy-level you require. If it were me, I'd keep the 50% perfect ones, and remelt the 50% rounded-base ones. Pretty soon you'll get the rub figured out, and they'll all be perfect.

Hope this helps, good luck!

[Bret4207]

+1 on Sagacious post. Mould temp is critical to good fill out. Rounded edges "sometimes" are almost a sure sign of a cool mould. The other possibility, considering your alloy, is poor venting but my money is on mould temp. Get a steady rhythm going, it's okay if the boolits are a little frosty, and keep going till you tire, run out of alloy or have enough boolits.

[Echo]

+1 for the above. I suggest minimal culling during casting - when the sprue is cut, I observe the bases of the boolits. If they look sharp, the boolits are dropped and added to the completed pile without further inspection. If the bases are rounded, or only one is rounded, I note it, drop the boolits, and return the sprue and round-based boolit to the pot. That way, the rhythm is maintained. After the session is finished, I may check the finished boolits - but my experience tells me that if the bases are right, the boolit is right.

[Shiloh]

Don't be afraid to turn up the heat. Are you putting the sprues back in and continuing to cast?? If so, your temperature is fluctuating preventing consistent temps, and therefore consistent boolits.

Shiloh

[HeavyMetal]

Larger boolit molds are harder to keep hot than smaller ones.

An idea struck me a few weeks ago and I've been playing with it for awhile and thats dipping the sprue plate itself into the alloy.

With a big boolit like your casting I think I'd try the following technique:

dip a corner of the mold in the melt for a slow 4 count, then dip the sprue plate for a slow 4 count then pour. Repeat.

What I have tried to do is get the mold hot enough to keep a sprue puddle "liquid" for a good 10 seconds before it solidifies. and then wait another 60seconds, or more depending on boolit size, before I cut the sprue.

When you cut the sprue the base of the boolit should be completely filled out and have a sharp edge all the way around it's base area. If you see this the odds are 99.9 % that the boolit is perfectly filled out and has all the sharp edges.

Dump it out and refill. The idea is to find what the mold likes and then do it the same way every time you use it!

I'll also agree with everyone else: do not QC while casting! This allows the mold to cool.

Play around with technique, once you find what works your reject rate will drop.

[leftiye]

Use a mold heater to control mold temp. As a plus, you can inspect your boolits as you go. This allows adjustments in technique that make your product better.

[mooman76]

The only QC I do while moulding is that that is obvious and that goes straight back into the pot while it is still hot along with my sprue cuttings. Keep things moving fast and that will keep your mould and sprue hot. I have no trouble keeping the sprue hot as I top pour and leave generous puddles on top. That keeps it hot.

[DCP]

I'll also agree with everyone else: do not QC while casting! This allows the mold to cool.


What is QC?