Well both actually

Higher tin or antimony will give you bigger but lighter bullets

running your lead temps high and or your mold temp low will throw undersize bullets. 

I preheat my mold in a home rigged oven of firebrick arranged around a hotplate. I put a thermometer in through the cracks in the brick and when it reads (500***) I know my first bullet will be a keeper. I try to keep my alloy at 700 to 720* for any lead/tin alloy

Hot mold/cool alloy will give you bigger bullets. In fact you can throw oversize bullets if you take this too far

Rattling the mold on a hard surface as you fill and cool will assist the alloy to fill out the mold

*** This thermometer is likely out of calibration but serves as a reference point for me. The key would be to work out your own details. Cast a bullet. If it has wrinkles bring the mold up another 50*

Details: alloy, pot temperature, etc. would be helpful.

Clarence

RayH wrote on Jun 3^rd, 2014 at 7:30am:


Are the bullets undersized with respect to bullets that you've previously cast using another alloy or undersized with respect to the advertised size for the mould? 

JackHughs

There are some informative posts on the castboolits forum, as well as on here, on possible solutions to your problem.

I have a .32 Hoch mould like that.  It's a bit undersized.

Are your bullets' grease grooves well filled out?  I have to run my Hoch nose pour moulds hot and fast to get good fill out.   

Chris.

JLouis (re.: How does it shoot?) Not outstanding one way or the other. When breechseating to 1/16" with my Weber tool, there is virtually no felt resistance and when removed from the barrel, there is virtually no visible engraving. Performance is less than comparable to that of my "Darr style" Hoch, base pour .322-205 tapered spitzer, with 3 lube grooves,  obtained from CPA at the time of my purchase of the rifle; and also, that of a Mos .322-.323D. 205 base pour spitzer.

Now, the rest of the story - The mold was a Hoch .322-200 nose pour from Midway. At the suggestion of Midway, I returned the mold to them stating my problem and including several bullets cast from that mold. They, with no questions asked, have shipped to me a brand new replacement mold. Being somewhat concerned that I, not the mold, was the problem, I made my original inquiry to this forum. When the new mold arrives, I intend to test it at a variety of casting temperatures, using my standard 25:1 "certified" mix from BACo. (My normal casting temp. is an indicated 725 & 775.) I have the highest praise for Midway and the manner in which they handle their business and I again thank my fellow shooters for your help both here and on the range. I remain confident that my best results are yet to come.

Do a shrinkage calculation ...Alloy shrinkage of cast bullets on ...
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My casting combinations where perfect filled out bullets drop are:
* Clean mold
* Pot and mold temperature where
** After a 5 second ladle pour with the spout stuffed in the sprue hole - the sprue puddle frosts in 5 second (8-10 seconds for heavier bullets in the 500gr range)
* Constant rhythm 
And hold the pot temperature constant to have a bell curve of small bullet weight variances