Odd looking mold mark left on the bullets

[Iron River Red]

I am casting 7mm bullets with a gc design and 3 grease grooves. I am seeing a large number of bullets coming out with a triangular shape mark that runs from the base up about half the bullet's length. Its only on one side and is quite deep. It looks like a perfect triangle that is long and narrow.

I'm running a Master Caster with a dual cavity for this caliber.

Also am getting more cold noses and flow marks than usual.

Any ideas on the reason why these marks are showing up? My scrap rate is way too high right now.

Red

[9.3X62AL]

Sounds like cold metal and/or mold. You might try smoking the mold cavities or spray graphite inside same to delay heat transfer.......but getting those mold blocks and/or the metal hotter sounds like a better first step.

[waksupi]

Red, I get this sometimes. It is a problem I cause myself. Watch carefully, as the bullet drops from the mold. Sometimes, I don't get mine open far enough, and it kind of bounces or falls against the one side of the miold, causing the blemish. Check it out, and see if this is what is happening to you.

[Iron River Red]

I tried upping the temp to 675 and still looks bad. Have run about 500 now and I ain't happy.

The mold was run then shutdown and left till morning. At that time I went back and found it had started to rust already. I'm worried the metal may be part of the problem. I wire brushed it real good and sprayed it with the lube from Magma and ran some more. Once the residue worked itself out, it started looking like it had before. The odd mark I think was the result of the mold pinching the bullet, like Waksupi had said. That has gone away, but the bullets still look bad.

[felix]

Up it to 800 for a show and tell. ... felix

[Willbird]

Also Red Is the temp you are quoting from the thermostat setting or a thermometer ??

Bill

[Iron River Red]

Both are good to point out. I will take the temp on up to 800 and get the feedback for you. The temp is from the dial on the pot. I think it may be time to get some sort of high temp thermometer.

I'm just amazed that this problem has shown up. The quality of the lead is the best I have had so far. (plenty of tin and Linotype)

Is it possible that there can be too much tin involved? I know we add tin to improve the surface tension and mold filling. However this run does have my highest tin content yet.

I just finished a run of 330gr .500 bullets and they look like new money.
The 7mm however, actually looks like it has some sort of pollution on the surface of the bullets.

I'm going to delve into to it further this evening and will report back tomorrow.

Thanks,

Red

[Iron River Red]

I should also mention that this batch consists of pure lead, linotype and tin. I weighed them out to give a ratio of 4% tin and 6% linotype.

I usually run w.w. and just add some tin. My friend calculated that I average adding 6/10 ths of a percent that way.

Nothing scientific about it. I'm just adding some tin and lino to the ww to improve the hardness and fillout.

I guess that the ww probably has some traces of this material in it already and I may still be low on one of the ingredients.

Red

[Bass Ackward]

I just finished a run of 330gr .500 bullets and they look like new money. The 7mm however, actually looks like it has some sort of pollution on the surface of the bullets.

Red

Red,

This statement is speaking volumes. You need to learn to speak .... mold.

[Oldfeller]

Red,

Take a kleenex tissue and rub the "corroded" surface of your bullet and see if it doesn't instantly shine up.

If so, then you have discoved frosty hot cast bullets -- good for you!

Now if you will just cast a little bit hotter and a little bit faster they will all be evenly and consistently frosty for you.

Frosty bullets are God's built-in way to tell you you finally got your bullet mold up to a good steady state casting temperature.

Go way way much hotter and you will see "shrinkage" of some section of your bullet. It takes a LOT to get to shrinkage though, the relative good range of a frosty hot bullet is quite large and once you are in the frosty zone you can do things that are amazing as far as FAST bullet casting speed and consistency in bullet weight go. The easiest casting is frosty hot casting.

Many unedumacated folks think slugs are supposed to be all shiney and they bust their balls to make all their slugs shine real pretty. They are always seeing occasional wrinkles and fill lines and agonizing over them. Surprise, give them shiny slugs a month or two and they get dull looking naturally.

Frosty on frosty hot well filled out slugs isn't more than a micron or two thick (check out how much lead was rubbed off on that kleenex) so don't sweat it -- frosty is your friend.

Oldfeller