UNder size ?

[Capt Klutzz]

I have been studying here for the best part of a year and am never less than amazed at the depth and breadth of the knowlege and diversity of info contained so please let me say thanx in advance for all of the knowlege I think I have gained at this board.

Having said that I have not learned enough so I have some stats to throw out and then I be very appreciative of some help.

Over this past weekend I had my first casting session with moderate success !
I have been collecting supplies for some time so heres the list:

Lee BP 20lb pot
Lee 312-155-2r
Mosin -Nagant 7.62x54R
Alloy = 10 lbs of Roto hb#2

Using data found here on Loads for Mil Surps. by C.E. Harris
BArrel slugs .310 (probably not as accurate as I should be on this)

I lubed the mold (spru pl. & bolt) using permatex 313


Heated the mold on a hot plate (not sure of mold temp at this point)
and brought the alloy up to about 750 F
Fluxed with beeswax and skimmed
The initial casts were VERY shiny and VERY wrinkled thruoughout the bullet body.
I also noted that the casts seemed very hard, very difficult to scratch with thumb nail.

Measurments came in at about .309

I cast half the pot back into ingots and added 10 lbs of recycled scrap lead and about 4-6 oz of leadfree solder to increase tin content.

CAst again and got slightly less wrinkles, seems a bit softer and increased dia to between .3095-.310

performed a verytentative "leementing" using an exacto knife, comet cleanser and crest and a very cautious lapping in the cavs with comet and a dremmel powered cast bullet.

Cleaned the mold again and this time heated the mold to about 375F and lowered the alloy temp to about 625-650 F

This time I could see less shiny and substantially fewer wrinles to the extent that I decided to load a few and test fire them although i was still barley attaining .310dia.

hardley any resistance thru the .310 Lee sizer

Used 13 grains of unique but no gc's and although they shot a foot high at fifty yds (rifle is scoped for 180 Gr. they were pretty much centered as far as windage).

My Question is what have i missed as far as getting this .312 mold to drop .312 bullets??
I have checked with 2 different sets of digital caipers getting the same results.
I have altered the alloy temp from 625 - 850 andam now checking the temp on the mold with a digtal thermometer, and I guess I forgot to mention that i tried comet lapping the cavs again.

The wrinkling seems to be getting better the more I run the mold (approx 7 sessions now) and the weight is coming in at about 153 - 153gr. but the dia seems relativly static.

Is this mold possibly undersized and in need of a trip home? or am I missing something.

Thanx again for the benifit of all of your experiences thus far.

[462]

Kapt,
Initial wrinkling was due to the mould not being clean enough. Eventually, with use, the machining fluids were somewhat burned off, resulting in better quality boolits. Though "the wrinkling seems to be getting better", it's still not clean enough.

However, boolits dropping .003" too skinny is a more serious problem, and I doubt that you are going to fix by changing the alloy or adjusting its temperature -- it's a lack of manufacturing quality control. Contact Lee or the seller and request an exchange.

[geargnasher]

I think you are doing everything right after you got the mould broken-in and started running the mould hot and alloy cool, I think the mould is just cut wrong. It happens. Most of my Lee moulds cast .001" to .002" larger than advertised when I use wheel weight alloy, but my 312-185 casts .3115".

Gear

[mroliver77]

Don't even try to size them, no need at this point. Cast, lube and load. I would keep the alloy a little warmer until you get better at casting or sprues stay liquid too long. Get that mold hot before casting! I like to see my first boolits a tad frosty verses wrinkly. The mold will cool as you use it. Don't worry about keepers for now. Just cast and work on technique. Don't fuss around looking and worrying at the boolits while casting, just cast and look for a rhythm. Melt every single boolit back down and try again if you do not get the results you are looking for.

Did you see any leading in your barrel? If not, pick out the best specimens and shoot some more of the concentrating on a group. Worry about point of impact later. If you can get them to shoot 3" or less groups with no leading keep at it and have some fun. If you don't have any, buy some gas checks as you will want to up the charge eventually anyhow.