Casting problem.

[Minerat]

I have a new 412640 Mehi mould and appear to be having some problem with getting a gas check for it. Then I send the shank measurements to Blammer he kindly pointed out that the diameter of the GC shank was large for the caliber of the bullet.

That got me to looking in to what else might be a problem. Let me say up front this is my first try at casting so it may be a operator error and not a technical problem so be sure to point out my weaknesses as appropriate.

The case bullets coming out of the mould are sweet but too big. Then problem is, that the diameter of the casting from all 4 cavities at the drive bands are 0.415 and the GC shanks are 0.398-0.399. Blammer said the 0.398 is too large for a 0.410 bullet.

The first step was to measure the GC shank dia on the mold and it was 0.390. I don’t have the tools to measure the drive band diameters. I think this is in spec but am not sure. So the following are the measurement and paraphrased responses to Blammer questions.

The GC Shank appears to be a straight. I took the measurements between the bullet base and the first band and it seems to be pretty uniform at the bottom, middle and near the first drive ban at a uniform 0.398.

The cast bullet diameter is 0.415 and it is round. The dia from seam to seam is the same as the dia from mid seam to mid seam on the GC shank across the front drive band seam to seam is the same at 0.415 and rotated 90 deg they are the same. Across both drive bands along the long side of bullet it's the same. The bullets appear to be round not oblong or flattened.

The mould is completely together and there are no flags at the seam. All of the hollow point pins are seated flush on both sides of the mould.

Could it be I am not keeping a firm hold on the handles and letting the alloy slump as it cools? I’m not choking it to death but just keeping the handles together.

I am not dropping the bullets until then spure had solidified for the count of 5 and the bullets just drop from the mould.

I wonder if the lead mix I have is the problem and is something different then what I was told it was. I got it from a friend who's dad passed and was a caster and he said he thought it was a WW + 1% tin. But it is throwing solid bullets at 206.5 instead of the 220 gr estimated. It is a little strange too that the diameter is 0.415 not the 0.412 that the mould is designed for, but the swelling on the drive bands is less then the swelling on the GC shank (0.002 vs 0.008).

Is it possible that the alloy swells after leaving the mould? But if so how is it so uniform from cavity to cavity and pour to pour?

Sorry for being so long winded and I appreciate your help.

Attached are 5 photos of a bullet from each cavity. I tried to get some contrast on the GC shank and the first drive band. It's a 4 cavity mould and I have been casting one of each HP and a solid until I get the hang of it.
102842102843102844102845102846

[freebullet]

Way to much heat could make them cast too big, but yours aren't frosted so I'm not sure there. Could you post a pic of the mold?

[Tonto]

Looks like Lino, will cast bigger and lighter. Nice looking casts.

[osteodoc08]

Try a known alloy.

The "industry standard" seems to be the 416 gas checks. That's what I use on a MiHec and Accurate molds of mine that are GC designs.

Truth be told, I rarely purchase GC designs in pistol calibers anymore unless I'm using them in a rifle. With good fit and good lube, I dont experience any significant leading up to almost 1500 fps out of a 6" barrel.

[Minerat]

Looks like Lino, will cast bigger and lighter. Nice looking casts.

I think I'll try a sample run using only wheel weight material and see if the over size still exists. With both the bullet size and the GC shank being a uniform 0.003 over it could just be a bad mould, so I'm going to do all I can to make sure it is not something I'm doing before contacting Mihec. So your suggestion about lino gives me another check just to be sure. Thans for the complement on the bullets they are pretty, can't wait to shoot some, especially the huge HP's.

Thank you of your help.

[Minerat]

freebullet,

I don't think it is heat as I have some with wrinkly ones from before the mould got warm and the metal was not hot enough. They measured over size too. I have to get my camera from work so will attach a picture of the moulds tomorrow.

Thanks,

[Wayne Smith]

Any estimate of how hard your alloy is? There is a sticky, I think up in the lead section, on using artist pencils to estimate hardness. This is a cheap way to do it.

I'm gonna guess too that you have a three part alloy, maybe lino, and that is what is causing the oversize.

[MT Chambers]

Noe sells or sold a slick tool to swage down just the GC shank so that you could seat gas checks it also served as a very good gas check seater, I use mine a lot, as all molds are not dimensioned the same at the GC shank.

[birddog]

I had blammer's 41T checks for my ranch dog mold and when they were sized even to .410" the checks fell right off. Had to go to .416"
checks after that. I'm starting to agree that the gas checks are not really needed for revolver cartridges, thats why I'm buying all new molds without GC's.
Charlie

[Minerat]

Thank you all for your responses. I talked to my friend today about the source of the alloy he gave me. He said then never used lino it was all wheel weights and tin so that solved that problem. I have not checked the hardness and probably won't at this point. With what the mould cost I think I'll contact Mihec and see what he suggests. I did cast with straight WW and it still threw them .003 over at 0.415 so I think it is the mould.

Blammer originally suggested the 416 GC but when I sent him the GC shank dia. he did not have anything that would work and offered to send some samples to try. He also suggested the mould was too large and we have a had PM discussion that has followed yo'lls suggestions.

I will shoot them thru a 41 mag Blackhawk and wanted to run them hot so choose the gas check for that reason. I have had problems with lead boolits (commercial cast) in my 44 mag and over the past months reading the information on the forums have come to the conclusion that this is probably more due to poor lube then running at 1500 fps. By that time I had ordered the GC model so I'll just have to suffer I guess.:-P

I'll let you know what the outcome is. Thanks again.

[Minerat]

I finally reached an end to this saga. I contacted Mehic and sent him the specifics of my problem. He had me do some casting with WW's only, to see what the moulds were throwing and they came out oversize too but closer to weight. He then ask for my shipping address and said he would send a new set of blocks.

Boy what great customer service. I offered to mail the oversize set back and am waiting an answer.

What I learned. This set of moulds cast the 41 bullets with WW's like this

Pins: Penta, Large, Small, Solid
Weight (grains): 206.0, 204.7, 213.7, 216.8
Drive bands: 0.415, 0.414, 0.415, 0.415
Gas Check: 0.398, 0.397, 0.398, 0.398

For the other alloy I started with the numbers are:
Pins: Penta, Large, Small, Solid
Weight (grains): 196.0, 194.9, 203.0, 205.0
Drive bands: 0.415, 0.415, 0.415, 0.415
Gas Check: 0.399, 0.398, 0.398, 0.398

To get these numbers I cast until I obtain 10 of each then weighed and measured to get the averages shown above. If I use the solids as a comparison then the WW's were approximately 1.058% heavier. If I assume the difference in weight is due to the addition of tin to the alloy and the difference is 11.8 grains then: 11.8/216.8=0.054%: 0.054*20lbs=1.089. This is roughly a 20 to 1 ration of WW to tin or Lyman #2. This is entirely plausible knowing the gentlemen that did the original mixing of the alloy cast some premo bullets.

Hope you found this entertaining or at least in formative and to quote Red Green "If the women don't find you handsome at least they should at least find you handy." (I think)

[hickfu]

If he doesnt want the old one back.... hone out the GC area and make it a PB boolit.



Doc

[Minerat]

Just got a PM from Mihec, a new mould is on the way and he asked me to not resell or give the old ones away so this may be an option. I made that promise. I have read some posts on how to bore them out but if I do that I'll probably send it out, so have to find a reputable machinist that has experience working on bullet moulds and can do it right. This block is just too fine to risk damaging it myself.

I will not hesitate buying another mould from Mihec. He stands behind his work, was prompt to respond to my PM and fix the problem.

[RobS]

Buckshot on this forum does good work on converting a mold to a PB and there are others as well. Erik at Hollowpoint molds does this service too.

http://castboolits.gunloads.com/member.php?67-Buckshot

[Minerat]

RobS,

You're a good man, I knew if I hinted at being too lazy to do the research someone here would help direct me to the right sources.

Thanks for the help.

[RobS]

No problem............it's about helping out a fellow caster.