Mold Size

[ksriverrat]

If a mold is cut to .358 what size will it throw using Lyman #2?

Also how much can one change the finished diameter by changing the alloy mix?

I am purchasing a GP100 & want to be sure I have a enough tolerance to play with so they can be sized to the gun.

[runfiverun]

there are about a million variables to this question.
a 358 cut mold won't quit make a 358 boolit,lead alloys shrink as they cool or you wouldn't be able to get them out of the mold.
the other than lead stuff in there shrinks less as it cools so it stays bigger.
your mold temp will influence final diameter also, unfortunately it usually will makes things worse not better.
it's hard to make bigger from one without having casting troubles.
there's always a lapping option,or custom.

[ksriverrat]

So based on what your saying a lot of said 358 molds aren't. Which has been my experience. I understand that in a lot of cases this number is used as nothing more than a model designation.

What I am not getting is why so many molds that claim a certain diameter throw any thing but that? I understand that many variables that exist.

Even more so once a manufactured product is placed in the hands of many different individuals, to use it to make boolits. That will be used in another mass produced product, a gun that can at times have even sloppier tolerances.

If the mold maker cant state with some accuracy what size their mold will throw at a given temp & specific alloy. Why bother? Understanding this capacity will of course up the cost of the mold.

I could have posed my question better. But I have reached a high level of frustration with some of my mold purchases. Maybe my expectations are to high?

[Mal Paso]

You forgot mold material, mold temperature, alloy temperature....................

Rough guess? you'll loose .001 or .357"

Many mold makers allow for shrinkage. My MP 432-256 is actually .4335"

Also are you sizing? How much bigger do you need to need to clean up out of round and casting variations? Some guys shoot as cast.

[ksriverrat]

You forgot mold material, mold temperature, alloy temperature....................

I see the point you are making. That being the issue with how I first worded my qustion.

I am wanting to try shooting as cast. Hoping to get as close to throat diameter as possible. But I have no clue as what diameter mold to order if I go with a custom made one.

[Mal Paso]

If you get a mold from one of the vendor/sponsors Here it should cast the nameplate size or larger. The alloy shrinkage is included in the calculations and the mold cut that much larger.

[ksriverrat]

Mal Paso, Thanks Man!!
That is exactly what I was looking for.
I am the worst at trying to get my point across or just make sense out of what I am trying to ask.

I was making it far to difficult to get the info I was wanting. Thanks Again!

[runfiverun]

great answers.
a custom mold maker will tell you.
they can also cut a mold to work with your alloy.
magma engineering tells you the alloy,and gives you a spec range.
they also send you some sample boolits.
the others just cut the mold and sell it to you.

[40Super]

I just tonight casted with a new Lyman 200 SWC that is supposed to be .452. My average came to .4505.some were .4495(the mold at it's coldest,melt at 750F).The bigger ones came when the mold was hot and the bullets were frosty. Too small for any of my guns.Back to Lyman I believe.I have to try some different things first,to make sure it is the mold. My Lee's were dropping big.

[ksriverrat]

a custom mold maker will tell you.
they can also cut a mold to work with your alloy.
magma engineering tells you the alloy,and gives you a spec range.
they also send you some sample boolits.


DANG! I never new any such thing as a custom mold existed. Until I came here. I did wondered about it.

I quit doing internet gun forums a few years back. Got sick of all the misinformation & regurgitated nonsense!

I found this sight completely by accident. The little I know from casting boolits seems to match up pretty well with what some others say here.

[Doc Highwall]

ksriverrat, here is a great web site that fits in with Castboolits.
This page has alloy shrinkage down towards the bottom left.

http://www.lasc.us/CastBulletNotes.htm


Be sure to mark it under your favorites.

[ksriverrat]

Thank You for the link to that great sight!

[Mal Paso]

Mal Paso, Thanks Man!!
That is exactly what I was looking for.
I am the worst at trying to get my point across or just make sense out of what I am trying to ask.

I was making it far to difficult to get the info I was wanting. Thanks Again!

Not a problem. I wasn't sure I was answering well. The great thing here is if I miss someone will say it better.

Slug your bore and throats. Bullets "should" just push through throats and be like '001" over bore diameter. If the throat is way over I wouldn't chase it. My Redhawk has .432 throats and shoots .431 boolits just fine (.429 Bore).

Most of the guys here size their boolits and you want to allow at least .001 over finished size for that.

The GP100 you get probably won't be strange and unusual and whatever mold you decide should be fine. You see a lot of problems here cuz this is where we find answers. It doesn't mean you are going to have problems.

[runfiverun]

you'll know when you got all you are gonna when the boolit just fall out of the lyman and they are greyish.
i would find the box and call thier customer service.
send a couple of your boolits along too.
i bet you get a bored sounding person that has heard the mold story 40-50 times already that day and yawns before telling you where to send it.

[ksriverrat]

The GP100 you get probably won't be strange and unusual and whatever mold you decide should be fine.

The GP100 I have now is pretty worn out. Not so much from number of rounds, though it has been shot a lot, but more so I believe from the use of pretty warm loads & the use of 2400 & jacketed bullets.

I am beginning to believe a longer, slightly heavier, warm loaded, cast boolit using a different powder will not as quickly cause the barrel throat & top strap erosion that a warm load using say a 140 gr. jacketed one using 2400 will

I am basing this not quite yet substantiated conclusion on memory of my past experience & talking with others who I know shoot gobs of 357 weekly.

[Mal Paso]

I like the Keith style boolit in 44 mag. I believe that's about 170g in 357. Punches clean holes in paper and meat.