New molds throwing bullets that are too big?

[zxcvbob]

I just tried out one of my new 6-cavity bullet molds this weekend. Lee 358-158-FP. The bullets look great, but they are .362". So when I lubrisize them to .358, there's not much left of the lube groove or the crimp groove. Is this a problem?

I'm not casting linotype; this was a mixture of half wheel weights and half soft scrap lead. I quenched the bullets in water when I dropped them out of the mold, but I can still scratch them a little with my thumbnail.

 

[NuJudge]

Some thoughts, and lots of questions.

My feeling is that you have a problem, but you have not told me enough that I can be sure. Can I suggest that before you do anything else, check the calibration of your micrometer or vernier caliper against a gauge block or a factory jacketed bullet. The cheap ones I have, have issues, generally measuring about .002" too large.

Also, Can I suggest you load several dummy cartridges with as-cast diameter bullets and see if they chamber. Can I suggest you also see if the as-cast bullets fit snugly in your revolver cylinder throats. Throat fit should be really snug, and Lead bullets should be .001" or .002" larger than barrel groove diameter.

My guess is that there is a lot of Antimony in your scrap, which makes bullets cast bigger. Antimony does not harden Lead much, except when there is Tin also present. Lower casting temperature may also give you a smaller bullet. Using a graphite mold release will give you a smaller bullet, by something in the neighborhood of .001":
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The more you size bullets, the worse they generally shoot. I like to load my cast bullets about .359" in the .38 Special/.357 Mag, determined by what the throats are on my revolver cylinders and what will chamber. You may be able to get away with .360". If you load too large a bullet in a case, the bullet will not chamber.

From what you wrote, I am guessing you are using Lee Tumble Lube and the Lee sizer. Using the Lee TL system, a too-large bullet will have its lube grooves seem to go away with a lot of sizing through smearing. If you are using the Lee system and wish to stick with it, I would get a larger ID sizer. My recollection is that Lee does not make a .359" or .360", but will make a custom one for you. Be aware that running a too-large bullet through a .359" die may not give you a .359" die (eg I have .366" die that, when I put .368" bullets through it, gives me .368" bullets).

You might also simply Lube, but not size, load normally, then use a Lee Factory Crimp Die to bring the cartridge back down to a diameter acceptable to your chamber.

Lubing in a RCBS/Lyman/Star with a lube such as 50/50 NRA formula through a die at as-cast diameter, then sizing down will prevent grooves going-away.

 

[Galil5.56]

Are the bullets pretty consistently the same dia from the center and ends? Takes a little practice to get used to casting a 6 cavity mold. Might use the mold a bit more to see if it settles itself in, and check for burrs, or other issues that might make the bullets too large.

As far as shallow lube grooves, I would let shooting decide if they are a problem. Hornady swaged slugs have always used a very light knurling w/o grooves that retains some form of liquid lube that has mica added. System seems to do OK, and these shallow grooves may be OK for you too. Even if the grooves are extremely shallow, Lee liquid Alox only needs a very thin coat to prevent leading in most instances.

Good luck.

 

[zxcvbob]

I'm using a Lyman 4500 lubrisizer with the black moly lube that came with it. I just finished up the stick of moly lube last night, and as it transitioned to the homemade lube that I put in there to push the moly stick thru, my lube won't stick in the extremely shallow grooves that are left (that's probably the fault of the lube.) I'm going to try lubing some .45 bullets that the lubrisizer barely touches (cast from the same alloy) and see how that works.

I have a Starret micrometer around here somewhere, I'll use that to check the bullets and to calibrate my cheap digital calipers.

 

[armoredman]

My Lee 2 cavity TL 124gr .356 mould drops at .360, but sizes well down to .358 AND.356, giving me one mould for both 9mm and 38Spl. Love it.

 

[NuJudge]

One more thought: look at the faces of the mold. If you have any Lead droplets that splash up and get on one of the faces of the mold, you will end up with larger bullets, and probably larger at the end where the droplet is. A soft toothbrush and strong light are your friend.

 

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I have a Lee TL 45 hollowpoint mould & I thought the idea of a tumble lube bullet was not to lube the grooves in a lubrisizer but to tumble them in the alox lube. The grooves are shallow & rounded from the start so I wouldn't thing the lubrisizer would seal around the grooves enough to lube the grooves only but would lube the whole bullet or very little in the groves.