Cash Bullet Weight Question

[442man]

I have just completed my first casting session with a 535 grain Postell mould which I plan to use in my Sharps. I played around with the temp and finally found 750f works good. The bullet weight varies from about 515 to 525 grains. I'm guessing the various temps I used could have some effect since I was as low as 675 and high as 780. The ones I cast at 750 are in the 524-525 range and that temp produces a nice looking bullet. Is it normal to have such a weight variance?

[OS OK]

I like posts like this one…they make me run off and search all around for an accurate answer. Outside of the mold being on the smaller diameter side or your mix being on the hard side of the weight standard the mold maker compares it with…I found this conversation that parallels your dilemma...

http://www.bpcr.net/forum/viewtopic.php?t=4497

Could be this will help..charlie

[MT Chambers]

Is it a single cav. mold? Are you adding or topping up the pot while you cast? What alloy are you using? Adding can throw things off if you aren't precise as to alloy of what you are adding, 5grains is less than 1%.

[442man]

Charlie thanks for the link. Looks as though I'm not the only one to see this happen. That was a good read.

I like posts like this one…they make me run off and search all around for an accurate answer. Outside of the mold being on the smaller diameter side or your mix being on the hard side of the weight standard the mold maker compares it with…I found this conversation that parallels your dilemma...

http://www.bpcr.net/forum/viewtopic.php?t=4497

Could be this will help..charlie

[442man]

MT it is a single cavity mould and I'm using the Lyman Mag25. Yes I have topped off but watch the temp so I don't get wide swings. The alloy I'm using is from a group buy several years ago on this site which is 2% tin, 4% antimony and .25 arsenic. The arsenic was added for those who wanted to do a water drop but I'm not doing that. I'm already thinking not topping off as you mentioned....

Is it a single cav. mold? Are you adding or topping up the pot while you cast? What alloy are you using? Adding can throw things off if you aren't precise as to alloy of what you are adding, 5grains is less than 1%.

[JSnover]

The ones I cast at 750 are in the 524-525 range and that temp produces a nice looking bullet. Is it normal to have such a weight variance?

So you're about 2% light and your variation is within one grain. You don't have a problem with weight, really. What do they measure?

[442man]

So you're about 2% light and your variation is within one grain. You don't have a problem with weight, really. What do they measure?

OAL is 1.421-1.422 Diameter is .358-359 I'm running through a Lyman 4500 with a .358 sizer and using SPG lube. This is my first attemp ever at casting bullets so it's been a learning curve.

[runfiverun]

well you found the sweet spot for your mold.
now the trick is to get it there and keep it there throughout each casting session.
anything short of that spot will give you weight variations.
variations that are big are hollow spots inside the boolits.

[bangerjim]

Temp variations in those big boys does make a difference. I have found that out.

"CASH" boolits on the other hand will shoot in anything, including slot machines@@@@@@. HA. HA.

[JSnover]

OAL is 1.421-1.422 Diameter is .358-359 I'm running through a Lyman 4500 with a .358 sizer and using SPG lube. This is my first attemp ever at casting bullets so it's been a learning curve.

Looks like you're good to go!

[442man]

Thanks Gents for your expertise!

[Walter Laich]

mine vary a bit more but I don't notice any real difference. Biggest problem for me is the guy pulling the trigger

[442man]

mine vary a bit more but I don't notice any real difference. Biggest problem for me is the guy pulling the trigger

Agree! As a side note I really like the way the Lyman Mag 25 holds a consistent temp. Also, I used Kroil as a release agent rather than the spray I tried first.

[runfiverun]

try no release agent and a nice clean mold.
molds are designed to let go of the boolit, you have to figure draft angles and such when drawing one up.
plus the alloy shrinks as it cools, otherwise it wouldn't ever come out.

[442man]

try no release agent and a nice clean mold.
molds are designed to let go of the boolit, you have to figure draft angles and such when drawing one up.
plus the alloy shrinks as it cools, otherwise it wouldn't ever come out.

Thanks for the suggestion, I'll give it a try. For cleaning the mold I used Kroil and gently rubbed with a brass brush, then sprayed with brake cleaner. Seemed to work pretty good.