Shrinkage!

[Trailblazer]

I bought a Saeco 441 four banger at the gunshow and made a first run with it yesterday. The 441 is a 250 grain 44 SWC. It had bullets in the cavities and the cavities looked clean so I made the first pour. Holy, Moly! There was oil in the cavities! Anyway I got it cleaned up and recommenced.

The bullets in the cavities look like linotype and they measure .432". I stuck the calipers in the mold and the cavities are .435" at the base. I need .430" bullets so I thought I was good to go and even with wheel weights I would get .430". I actually got .428" to .429". That means I had total shrinkage of about .007". I was all set to beagle the mold until I had a thought.

The sprue holes are very small - only about .090" and it was a bear to get the bases filled out. I ran the alloy hot and had to hit the hole precisely to get all bases filled out. Even then I often had one that wouldn't fill out. So I was also going to enlarge the sprue holes before I cast anymore. I got to wondering if the larger sprue holes would make the bullets drop larger? Or is .007" shrinkage in a 44 bullet normal with wheel weights?

[leftiye]

"Break" the edge (bevel the edge just a few thou.) of the mold halves with a fine toothed file at the tops of the cavities just a little. This will give you some more venting to release air, and thus give you better fillout at the bases. Use a mold heater to run the mold hot 330 degrees and upwards (and run the lead cooler - say 600 - 650 degrees) mold will expand, better fillout as lead doesn't freeze instantly, and maybe less shrinkage. If it still casts too small, I'd lap it a little first. The first thou comes off pretty fast. It makes the boolits release easier too (polishing).

[44man]

You have to remember that lead will shrink at first smaller then the mold cavity. Then with time they expand a little. More antimony and more expansion. Measured right after they are cast will show smaller boolits. Pure lead will not grow.
Casting hotter will expand the mold more and make larger boolits but if you get too hot, the lead will shrink more. Try 725*, 750* and 800* to see what the difference is but you still need to let the boolits age.
Casting with cooler lead will not keep the mold at temp or allow boolits to fill. The mold works best if pre-heated to 500* before casting.

[454PB]

This is not surprising, most of my .44 moulds will cast .432 to .433 with linotype, and .429 to .430 with WW alloy.

[Trailblazer]

It will be beagled! Thanks.

[Morgan Astorbilt]

Every time I see the title of this thread, it reminds me of a certain Seinfeld episode.:-D
Morgan

[44man]

Ask this old man about "shrinkage"! :bigsmyl2:

[selmerfan]

I was in the pool!!! Seriously though, if I size the same day I cast, will the boolits "grow" some post-sizing? Or have I opened a big can of worms...
Selmerfan

[docone31]

On shrinkage, and growing.
I cast some .312/185 Lee bullets. They came out great.
I just was looking at some of the last batch. The sprue hole seems to be projecting out of the base. About .002. It also looks like a wart. Growth from inside. They measure, random sampling, .313, .3125, .3135, .312.
Some of the sprue holes have a slight hollow with the outgrowth, some are just outgrowth, some are dead flush.
I cast and water drop. I size the next day. Unsized bullets stay the measurement of the sizer.
I can understand the hollow in the sprue. As metal cools it shrinks. The hollow is slight but visible. The outgrowth is slight and visible.
The last batch of .45ACP all had just a slight depression in the sprue hole. All the same. The .357 castings the same. The .303 castings all have the changes in the sprue.
I can understand as the bullet is longer than the ACP, and .357 although the grain weight is in the middle of both. Is the length a factor in shrinkage while the metal is plastic?

[GabbyM]

I have one of those Saeco moulds from circa 1970's. It had a horrible spur plate. Sounds like you've one of those. Regardless of shrinkage it sounds like you were on the right track with drilling them out so you can get lead down the hole. Mine had burrs covering half the hole and no two holes the same on a 4 cavity. Needed to countersink the holes again after drilling to resharpen the plate. Then honed the bottom of the plate. Total PITA. Saeco went through some change of ownership and hard times back when. I've purchased about a dozen Saeco moulds just this year. They are all great.

[44man]

I lathe turn the countersinks on my plates and when they reach super sharp the holes will be around .200". I polish them to a razor edge.
Small sprue holes are a pain to cast with.
I would open them up with a countersink.

[Trailblazer]

The plate does have a spur on it. I measured a bunch of other molds and found sprue holes from about .125" to .150". I will probably try .150" first. I hadn't thought about lathe turning them. I will probably countersink them even though it isn't quite the same angle. The mold casts great if you can get enough lead in the hole. When I get the sprue holes enlarged and the size issue fixed it is going to be an excellent mold. I like Saeco molds a lot and have several. Saeco was just a few miles up the coast in Carpinteria for a while and there are quite a few floating around here.


I decided to try bumping the bullets. I found out that my new (used) Lyman .430" size die is really only slightly over .429". Going to have to hone that one. I used a .431" die instead. That worked but now the bases are convex and I am not sure how consistent the bumped bullets are. Going to shoot some and see how they are.

I don't know anything about Seinfeld as I don't watch TV but I don't think I have the shrinkage problem he is concerned with. I have a lack of fillout just like my mold!

[jim4065]

Has anyone ever checked for a shrinkage difference between water-dropped and air-cooled? It seems like some of my boolits from the same mold and casting session are smaller (less distortion when sizing). Since I got in the habit of occasionally dropping six on a towel instead of the water bucket (it lets me look at a boolit without fishing in the water), I've noticed that some are hardly polished in the sizer while others are shiny all the way around.

Just wondering if this road's been traveled here before - hate to get involved in a lot of measuring, recording and averaging if the answer is already known. :???:

[GabbyM]

I've heard that dropping bullets in water will stop them from shrinking. Thus giving a larger diameter bullet. I've tried it a couple of times with no luck. Variables likely run a person in circles. Always worth a try. I was probably dropping them to late?