Lyman 358311

[38 Super Auto]

I picked up a used 4-cav 358311 and I cannot get it to cast good bullets. The first thing I did was clean up the mold face and cavities with a brass brush and scribe out all the vent lines. I cleaned up the top of the mold and bottom of sprue plate with 320 followed by 600 grit.

Before the first use, I lubed the mold top and sprue plate with Bullplate and let it rest for about 30 min on a hotplate. I wiped off all the extra lube and started casting. I am getting good bullets from two of the cavities consistently. None of the cavities have wrinkled noses. The defects are in the driving bands and bases. They are not huge, just annoying.

I am using a WW/lead alloy with 2% tin added and I am casting at max temp for my Lee pro-20 pot.

I can't help but believe it is venting related, but I already opened up the vent lines with a scribe.

Any suggestions?

[docone31]

Have you smoked the mold? I find, unless I candle black the mold, I get a mess. I have also had success blueing iron molds.

[Trapshooter]

I had a similar problem with a dual cavity 452460 mold and a Lee pot. No matter what I did, the bands weren't always sharp and square. I tried hotter, colder, more tin, sacrifice two (2) chickens at midnight, and nothing seemed to help. Then I noticed that the flow rate was way less than it used to be. Giving the spout a good ream and clean so the metal comes out in a fairly forceful stream solved my problem.

Trapshooter

[ChuckS1]

I had a similar problem with a dual cavity 452460 mold and a Lee pot. No matter what I did, the bands weren't always sharp and square. I tried hotter, colder, more tin, sacrifice two (2) chickens at midnight, and nothing seemed to help. Then I noticed that the flow rate was way less than it used to be. Giving the spout a good ream and clean so the metal comes out in a fairly forceful stream solved my problem.

Trapshooter

I have the same mold and pot. The only way I could get nice sharp bands was to run the pot on the 8 or 9 temperature setting. To make it worse, only the cavity closest to me would fill out. The other cavity, no matter what I did, wouldn't fill out the base. And then to add insult to injury, the high temps for the alloy (I was using WW) gave me undersize boolits. I finally gave up and ordered a Ballisti-Cast #668.

[38 Super Auto]

Trap, Thanks for the input. I have not messed around with flow rate on this mold. I'll give it a try AND I'll keep the chicken sacrifice at midnight trick in my back pocket. I have tried mold release and am still seeing issues. :drinks:

[leftiye]

Not to wind up the old gramophone (the one with the broken record on it), but if you can get the mold hot enough it will very probably cast (needs to be clean, of course). With problem molds a mold heater worked into your casting routine will do this - no questions asked. Most people don't use them because they can cast faster with the fill/cut sprue/drop/fill approach. For example, hollow base and hollow point molds - remove the wooden knob - handle the pin or plug with pliers - and set the mold on the hot plate with the pin/plug in, right side up while you inspect the freshly dropped boolits. Really helps them pesky voids that wanna form at the apex of the pin/plug. To give perspective, if your heater is adjustable/controllable, then you can cast anything from shiny to totally destroyed by frosting with 600 degree lead. Really makes a dent in the problems with casting pure lead. Makes GOOD boolits!

[Glen]

The vent lines are working just fine... for the body of the bullet. Once you get the mould filled up past that point, those vent lines can't provide any more venting. The problem you describe is a classic case of the base not being adequately vented. Double check the vent lines closest to the sprue plate, and especially look for burrs where those lines meet the cavities. Try loosening your sprue plate just a touch and see if that helps. You can also knock the edge off the top of the mould faces for perfect venting, but try loosening your sprue plate first.

[willwork4ww]

And if all else fails, weld up the problem cavity's fill holes in the sprue plate. At least then you don't have to sort the bad from the good.
:-D

[LAH]

The vent lines are working just fine... for the body of the bullet. Once you get the mould filled up past that point, those vent lines can't provide any more venting. The problem you describe is a classic case of the base not being adequately vented. Double check the vent lines closest to the sprue plate, and especially look for burrs where those lines meet the cavities. Try loosening your sprue plate just a touch and see if that helps. You can also knock the edge off the top of the mould faces for perfect venting, but try loosening your sprue plate first.

Plus 1

[GabbyM]

Sounds to me like you did a very good job of surfacing your spur plate and mould top and now have an air tight fit.

[HORNET]

Is there any venting between the cavities but parallel to the cavities so that the vents running from one cavity to the next aren't deadheaded? That air's got to have someplace to go when it leaves the cavity and it can't if there's a boolit in the previous cavity blocking things off. Worth a try, I usually even do it on doubles.

[38 Super Auto]

Casters, Thanks for all the input. I'll try a few things and report back. That means more casting, nore loading and additional range time to schedule. Can I apply for overtime pay? :)

[leftiye]

Yup! Ya can have all the overtime ya want. Just apply to that there .38 Super Auto guy to get paid.

[Dale53]

I have the Lyman 358311 RN four cavity mould and it casts just fine. I would relieve the top corner of the blocks (centered over the cavities as suggested by Glen. You only need to break the corner (about .005" - yes, that is five thousands wide on each side as you just need to let the air out). Do it too much and you ruin the mould.

You should also NOT apply Bullshop's Sprue Plate lube until the mould is up to heat and do it with the bullets still in the mould to prevent oil from getting into the cavities. As soon as you apply the oil to the top of the mould and the top and bottom of the sprue plate, then wipe it off. Only a film is needed and a "film" will not migrate to the bullet cavities.

Dale53