shrinkage

[fusionstar916]

Bought a 230 gr 300 blackout 2 cavity mould from Lee at midway and the boolits are coming out anywhere from .304 to .309 even WITH Alox on them. They are quenched, I'm using wheel weights smelted into ingots. I have the .309 Lee sizer but the bullets are so undersized, they are pushing through with no resistance and only a few were sized evident by the shiny swaged areas. This alloy works fine for my 175 gr truncated .40 6 cavity Lee mould.

I casted 40 lbs of boolits beforehand without measuring them because they were coming out nice and filled. My barrel slugs at .308
Is it my alloy? Temperature? Mould? Measurements confirmed by 2 calipers.

[nhrifle]

Do a forum search for your mould. Others have had that issue with this mould, and I am also one, though my boolits vary from .307 to.311 and about .002 out of round. I shoot them as is. I would say yours are coming out on the small side. I think another member found that the alloy was the problem and once he found what it liked it cast fine. If nothing else, give Lee's warrantee a shot.

Try measuring the boolits witha known good micrometer. Calipers are ok but not as accurate as a good mic, and even a good set if calipers can be off by a couple thou. I do precision machining and this has been proven to me numerous times.

[fusionstar916]

Called my brother and ran over to borrow his mic, boolits coming out anywhere from .3046 to .3099 with no obvious differences. Front band measures .3043 to .3075, trailing band right before boat tail measures .3046 to .3099

They coming out egged by .0002 to .001

I smelted my slugged sinker so I will have to redo that.

I can't find any related posts regarding undersized boolits and the Lee/midway mould. I like a hot mould and frosty boolits. They are usually dropped in a bucket of water. Any of this effect the shrinkage to the degree I'm experiencing?

[nhrifle]

Water quenching might have something to do with it. It's what I do with all my cast boolits except what I shoot with black powder. Since we are both getting odd sizing as cast and are water dropping, we should try air cooling. If the weather is decent this weekend I plan on casting for my pistol so I will try it. If you get good results before I do, please post them.

[williamwaco]

Called my brother and ran over to borrow his mic, boolits coming out anywhere from .3046 to .3099 with no obvious differences. Front band measures .3043 to .3075, trailing band right before boat tail measures .3046 to .3099

They coming out egged by .0002 to .001

I smelted my slugged sinker so I will have to redo that.

I can't find any related posts regarding undersized boolits and the Lee/midway mould. I like a hot mould and frosty boolits. They are usually dropped in a bucket of water. Any of this effect the shrinkage to the degree I'm experiencing?


This amount of out-of-roundness is actually quite good.

I would say the undersized diameter is unacceptable and would at least attempt to get it replaced.


.

[nhrifle]

Ok, fired up the pot today and cast up some 9mm boolits and a couple hundred from the Blackout mould. WW alloy, no additives, fluxed, allowed a 3 second dwell time after sprue freeze for stabilizing. Do not have a way of measuring the temperature of the melt, but I am using a Lee Pro 20 lb bottom pour pot and I keep it set at heat level 6. I made sure the mould was clean before casting. Boolits were air cooled on a soft cloth. Measurements taken with a Starrett 230 micrometer, calibrated by the QC dept at work.

Nose diameter before frt driving band, .2986 - .301
Front driving band, .3044 - .3072
Rear driving band, .310 - .3128

This is an average of 10 boolits measured at random points on their circumference at the locations specified. Mine are not undersized, but are still coming in at around .003" out of round. That probably won't make much difference as it will be drawn down in diameter by the barrel. I may try to lap the mould cavities to get them a bit more round but I havn't decided yet. Not real interrested in wrecking an otherwise good mould.

The boolits all look good, with excellent fill of the cavities and dropped right out when the mould got hot. Had some with minor flash but that was probably my fault for not closing the blocks completely.

Havn't had a chance to load and shoot these for accuracy and probably won't get a chance to do so until next weekend.

[blikseme300]

I found that this mold needed more tin to fill out properly. Initially the micro grooves were not properly defined and the boolits were undersized. Added another .5% tin and all is well. I am using 45-45-10 to lube with no sizing and the results are awesome.

[nhrifle]

Thats good to know, thank you. Maybe a roll of tin solder will help with the concetricity of the boolits as well, it's worth a shot anyway.

[44man]

Out of round is common and as long as a boolit is still large enough, ignore it. Undersize molds need sent back and there is nothing an alloy will fix.
Water dropped WW boolits will harden and EXPAND some with aging a week or so.
Out of round is simple to explain. The mold expands with heat and the cavity will get SMALLER at 90* to the part line. A perfectly round cut mold can not make a round boolit---ain't going to happen!
I get my molds hot by casting and put the cherry back in, turn with a wrench and cut a lot more metal out and get rounder boolits. If I had a way to measure, a mold that makes round boolits will be a little OBLONG when cold.
The hardest thing to explain is a cavity is not a hole in a block that expands from the center but is half a hole on an edge.

[fusionstar916]

Finished watching the niners/falcon pats/ravens games and fired up the drippy lee.
I leemented the mould due to minor sticking while watching the games, afterwards poured about 20 quenched and 20 aircooled.
They both came out undersized still with no discernible difference. I threw about an ounce of 50/50 of tin solder into the pot, fill out was excellent. Boolits came out .3055 to .3099 right before the boat tail at the largest in both cavities.
My lee pot doesn't seem to manage temperature very well. At 4, with half a pot. I noticed my lead was glowing.. It was WAYYY up there. My cheap infrared temp gun couldn't read the temp.
Ill load up 100 and shoot them when my dies come in.


How much do wheel weights expand after a week? Should I let the boolits sit for a week then resize?
Where can i find a custom expander for my lee sizing die?
Sorry for so many questions.

Im going to spend a couple more hours polishing up this mould. Hopefully it will enlarge the cavities enough so I dont have to send a $24 mould back for $8 shipping and a 2 week+ wait.

Thanks guys!

[44man]

How much do wheel weights expand after a week? Should I let the boolits sit for a week then resize?
It depends on boolit diameter. Smaller calibers expand less. You could get .0005" to .001".
I would just lube and size soon after casting, let them sit a week and load.
I had a few Lee molds too out of round and sent them back. They replaced them and all is good again.
I suppose on the average a boolit will be .001" to .002" out of round.