Two new Lyman moulds with poblem

[Bob Maerdian]

I just received two new Lyman moulds from Midsouth. One of the moulds is 410660 (I think) and the other is the 45-70 version of the same bullet that weighs about 480 gr.

When I opened the box and removed the mould both looked pretty good. The sprue plates need to be a bit looser and I need to break the edges of the sprue plate. When I held the blocks up and looked through the cavity I was surprised to see light at the bottom of the cavity on both moulds.

I have not degreased or cleaned up the moulds yet and am just wondering if a good washing and de-greasing will cure the problem. Where might I find instructions on tuning a new Lyman mould?

Thanks for your Help,

Bob

[Ben]

There could be some " crud " on the block faces that is preventing them from fully closing.

The alignment pins could also need a tap or two with a large brass punch to set them a little deeper.

I have some molds ( not necessarily Lyman brand ) that show a small amount of light between the blocks and they cast very good bullets.

I'd clean the blocks well and cast with both molds, if the dimensions of the bullets are within " specs ", and you don't have flash around your cast bullets , I wouldn't be concerned with it.

Ben

[bhn22]

Often, the oil that Lyman uses to prevent rusting hardens and prevents the blocks from closing completely. Go ahead and clean everything up really nicely, wipe them down really good and see if the problem is still there.

[geargnasher]

Lyman typically coats their blocks with a preservative of some sort. Clean them up good with solvent and a toothbrush, then brake cleaner, alcohol, or hot-soapy water and see how they do. A little "daylight" doesn't hurt most of the time as long as the mould casts round boolits and the cavity halves line up correctly.

Gear

[JonB_in_Glencoe]

Another thing should be mentioned with a Brand New Iron mold.

After you clean it up (I use hot water, dawn dish soap, and a toothbrush) and cast the first time with it, If it has some quirks...my first thing to do is Heat cycle the mold by letting it cool, then bring it back up to temp by casting a bunch, then let it cool again, repeat that about 3 times. That will season a newly machined Iron mold, and that alone will solve some initial quirks.


edit: The short version of what I was rambling about, many times a mold casts better after it's used a few times