cast bullet weights

[swiftak]

I have a question for you guys who cast your own bullets. Today I finally decided to give it a try. I have the mold from Lee for 125 gr 9mm bullets. Its the two cavity mold. I used wheel weights. I followed the direction for warming the mold and poured the lead into the mold cavity. Most of the bullets looked ok.Some were pretty shiney and some had the frosted look that I've heard mentioned by other people. Some I need to melt down a give it another shot. What my question it, is why none of the bullets weigh 125 grs. I have 20, and the weights vary from 112 gr to 119 gr. The mold was filled all the way. Is the kind of lead that I'm using incorrect? If so, what should I be using?
Thanks for your input.

 

[sqlbullet]

The bullet weight will vary based on the lead alloy you are using. Usually, the molds advertised weight is based on a specific alloy, like 1:20 or Lyman #2, etc.

My 175 grain LSWC .401 lee mold (2 cavity and 6 cavity) both drop bullets with an average weight of 172.5 grains from my alloy. I am developing data right now for my son's science fair project (Effects of heat treatments on metal alloys) that seems to indicate there is a variance from the temp of the lead when cast.

So, casting under weight is not really uncommon.

What is a little disturbing is both how far under weight you are, and the extreme variance in bullet weights. The standard deviations I see are in the ±1 grain range. This would seem to indicate the presence of a variable qty of air in the bullets (assuming there are no wrinkles, and they are well filled out.

Couple of tips. Set you pot on a specific temp setting (or measure temp if you have a thermometer) and let it stabilize at that temp. Ensure the mold is evenly heated. Ensure you have a good 'sprue' puddle on the top as air does enter the alloy where it cools rapidly.

 

[Dean Williams]

The weight of the bullets that the mold throws is dependent upon the casting alloy. Most molds are calibrated to the Lyman #2 formula. Wheel weights aren't quite the same make up as the Lyman stuff.

Your bullets should all come out weighing within a grain or two, though. The variation in yours could simply be that the mold isn't always filling out completely. You can sometimes see where this is happening, usually at the base of the bullet. If the corners aren't sharp on the base and in the lube grooves, the mold isn't filling out completely. Usually caused by your lead not being hot enough, or the same for the mold.

Don't worry about frosted bullets, as long as they are properly filled out, and if they're frosted, they usually will be, unless you have some oil in the mold.

One other possibility is that the two cavities are throwing different weights, though I have never seen this vary more than about a single grain in the size of bullets you are casting. Check by using only one cavity for about 10 bullets and see if they are the same. Do the same for the second cavity.

 

[sqlbullet]

Also, check out the article here on casting. Lots of good photos of sprues, bullet bases, etc.

 

[swiftak]

Dean, Thanks.
Some of the bases were a little rounded instead of sharp. Also some of the bullets had a wavey or wrinkled look on the surface. Just what is the right way to heat the mold? Or the best way?

 

[swiftak]

sqlbullet, Thanks for the info. Thats a good article.

 

[Dean Williams]

Swiftak, the wrinkles, or wavy parts are usually caused by one of two things. The mold has a little oil in the cavities, or it's just not warm enough.

Clean the mold with something that dries grease free, like lighter fluid or Coleman camp fuel, (or any kind of white gas/naphtha). Alcohol will work, but it's not a very good de-greaser, really. Mineral spirits will work if it doesn't have anything in it that leaves a residue. Acetone will work.

When I heat up my lead, while waiting for it to liquefy, I place the molds on top of the lead furnace to let them get hot. Usually then I pour about half a dozen casts before it starts to throw good looking bullets.

Don't forget to lube your sprue plate exactly as the Lee instructions say.

 

[sqlbullet]

Also, when lubing, the sprue plate, be very sparing. Seems no matter how hard I try, I always get a tiny bit of lube in one of the cavities, and then it is 30-40 casts before that cavity throws a good bullet again.

Speed is helpful as well in keeping the mold temp up. I cut the sprue as soon as they solidify, and dump the bullets, close and refill as fast as possible. When my mold is hot, it takes about 5-10 seconds for the sprue's to solidify.

 

[GP100man]

the temp will affect weight also, the hotter the alloy the more it`ll contract .
weigh all the frosty ones ,then the shiney ones , you should find 2 distinct groups of boolits.

go here for more info www.castboolits.gunloads.com/


GP100man