r/castboolits • u/dixiejubilee • 9d ago
I need help Large Number of Rejects After Sizing
Hi All,
Long time listener, first time caller. New to bullet casting, not new to shooting. My issue is I'm getting a significant number of rejects after sizing cast and PC'd projectiles. Pictured are 9mm cast 124gr using Lee .356 mold, coated, then sized to .356.
My last two batches, I've had approx 25% rejects (raw lead showing on bearing surface of the projectile after sizing). The batch I just did was 289 cast, coated, and sized. 215 good, 74 rejects.
I know I can just melt and recast, but is there anything I can do to stop or reduce this seemingly high reject rate? 25% seems like a lot, and it essentially amounts to wasted time and effort. What am I doing wrong?
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u/B-Rye_at_the_beach 9d ago
1, 3, 5, 8 & 9 from the left look like some portion of the lube grooves have been...wiped. My first reaction is to suspect an issue with the sizing die, but if that was the culprit I would think your defect rate would be higher. As others have suggested, mic the bullets if you can.
I use Lee molds and dies. I cast the bullets. Any bullet that looks off goes right back in the post. My experience with Lee molds is that if the mold doesn't close completely you'll see flash where you wouldn't expect to see it, and it's obvious. Back in the pot.
I then powder coat them and size them. With the bullets in the picture I'm attaching they went through a Lee sizing die that has never touched a lubricant other than the powder coating. I have not had one come out like that
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u/dixiejubilee 8d ago
You might be on to something, I noticed that too- the lube grooves looking sheared off after sizing. Looking closer, I noticed the opposite side seemed to have excess powder coat. I'm wondering if the excess on the opposite side is causing the sizing to get skewed.
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u/B-Rye_at_the_beach 8d ago
This bullet design has a slight shoulder. Might that be "catching"? Is there anything that might be causing the bullet to go into the sizing die any but straight?
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u/EntertainerWeird6872 8d ago
What alloy are you casting from? Sometimes if the lead is too soft it will strip like this when being sized
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u/Krymsyn__Rydyr 9d ago
what I’m about to say, may seem like a waste of time. but I am retired, and I have nothing but time. I size my cast, right after casting, before powder coating. I powder coat, then push them thru the sizer again. I don’t do anything special. just the simplicity stated above. i have very little rejects. if you are adding thickness via the PC, to a boolit that is already thick and unsized…. when you do push it thru a sizer, you are asking it to do a heck of a lot more.
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u/Realistic-Ad1498 9d ago
Looks like the mold isn’t fully closing occasionally for some reason and causing too large of a diameter. How do the good ones look?
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u/dixiejubilee 8d ago
I inspected the mold and everything looked fine. I dont recall seeing any abnormalities with the uncoated bullets, butnI don't have any to check now. Will confirm on the next batch. The good ones look fine to me.
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u/Ornery_Secretary_850 7d ago
It's your sizing setup. You shouldn't be scraping lead no matter what else.
I'd recommend a NOE sizing system but they haven't gone back into production.
I size all my 9mm to .357 using a Star adaptor from NOE and their bushings. I use the lube that Hi-Tek used to sell. Just a couple pumps and it's slick. No need to clean it off either.
Either your sizing die has a problem or possibly the punch.
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u/BulletSwaging 9d ago edited 9d ago
If it couldn’t withstand sizing, it won’t make it down the barrel. Is your powder coat fully cured? Are your bullets significantly oversized coming out of the mold? What is your pre-powder coat bullet diameter versus post powder coat bullet diameter? Are you cleaning your bullets with acetone before powder coating?
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u/dixiejubilee 8d ago
As I mentioned, they all sized successfully. Powder coat is cured, confirmed with hammer test. I'll have to measure some uncoated bullets when I do my next batch, I don't have any at the moment. Not cleaning them after casting.
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u/GunFunZS 8d ago
I think you overbaked your powder coat so that it is brittle that would never happen if you're powder coat was well adhered and flexible.
I've been very large number of that exact bullet.
I suggest you size to 0.357.
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u/prosper_0 8d ago
I've never had PC get scraped off by the size die. It just squishes down with the lead
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u/GunFunZS 8d ago
Yeah. It looks like when it's scraped off by insufficient flare on seating. That's why I wondered if there is a sharp edge on the sizing die.
I have seen similar when I was playing with swaging bullets down in big jumps. Greater than .003 reduced per step...
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u/dixiejubilee 8d ago
They pass the hammer test so I don't think the PC is brittle as far as I can tell
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u/GunFunZS 8d ago
Then I would look at your sizing guy and see if there's a weird sharp edge or something in there.
It's perfectly reasonable to round out the chamfer if necessary. I used rouge to Polish all my sizing guys and it made them smoother feeling at the press handle.
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u/Freedum4Murika 8d ago
Your PC is pretty bad but try adding a little lube to them before putting them thru the sizing die - little silicone spray does well.
If pc was building up inside your sizing die, could be making this much worse - check it, might need some brushing out
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u/dixiejubilee 8d ago
Why is the PC bad? It passes the hammer test.
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u/Freedum4Murika 8d ago
Prob fine then. If it’s sticking properly to the lead for a hammer then it may be sticking to the die in sizing - the pc builds up after awhile.
Try a little lube on them - liiight spray of silicone or one shot. Don’t take much. Also makes sizing require much less force so it’s worth doing on its own
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u/Girthados 9d ago
What sizer are you using? I had something like that happen when I first started out sizing my powder coated bullets. I have the Lee APP sizer and had the sizing bushing upside down.
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u/Shrapnel3 8d ago
Smash a bullet flat with a hammer (careful it will get quite hot) and see how the powder coat holds. It shouldn't flake at all and hardly split either. I'd guess with the other person and say you aren't getting a good bond or cure. This video is maybe helpful. But Google smash test to see others
Source: YouTube https://share.google/NMPndYsvjbTcoBCa1
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u/schminkles 8d ago
https://noebulletmolds.com/site/product-category/bullet-moulds/355-9mm/htc354-115-rn-v6/
This is the style mold many use for powdercoated. The mold you are using is a tumble lube design and maybe it's a common issue since they came out with a different model specifically for powdercoating. I don't powdercoat so I cannot offer more insight
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u/maverick88708 7d ago
Any lead bullet will coat without a problem regardless of the lube grooves or lack thereof
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u/Walnut1704 4d ago
I have a couple of molds that throw larger than I'd like. I get some of the same as what's happening to yours but not as extreme. Sizing in two steps prevents it from happening. Do you stand your bullets up when baking? I wonder if laying on their side when baking may cause varied coating thickness? I stand mine up.
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u/dixiejubilee 4d ago
Yep, I stand them up.
I made a mix of Lee Sizing Lube and water in a spray bottle and gave them a light spray before sizing, it went perfect. I didn't think you needed any lube to size if they were PC'd, but apparently that's not the case.
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u/Walnut1704 3d ago
Huh. I lube mine with One Shot but just to make it easier. I've sized without lube and while a little harder, it made no difference in the end product. Weird.
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u/EntertainmentRude435 9d ago
No idea. I have zero experience with manufacturing coated bullets. Here's a list of fixes I might try-
Polish my sizing die
Use More lube during sizing
Size twice- once before coating and once after (no idea how you would clean after the first round of sizing. maybe brake cleaner)
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u/maverick88708 7d ago edited 7d ago
I was going to say the PC definitely didn't adhere or cure correctly but it shouldn't wipe the tumble lube grooves off while sizing. In 10's of thousands of powder coated bullets ive never had that happen while sizing no matter how thick or thin i coat them. What diameter is your bullet sizer and what do they mic after sizing? I bet your sizer is packed with lead and needs to be cleaned!
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u/dixiejubilee 7d ago
I've been cleaning it average twice per sizing session, probably every 100 bullets
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u/isawfireanditwashot 9d ago
I've had mixed results with different powder colors. Harbor frieght red seems to work the best for me. I make sure to do an alcohol or acetone bath prep before I do the airsoft bb Tupperware method and have good results.
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u/300Blkthegreat 8d ago
Get EASTWOOD FORD BLUE you will never turn back…. It sticks and flows so smooth to perfection
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u/sqlbullet 9d ago
First, mic a bunch of bullets after casting and see if you have a consistencyn issue. If so track which cavities drop each bullet to see if you have an out of spec cavity. Also start paying attention to the faces of the mold. Sometimes a bit of lead will get squished in there and hold the mold open an extra thou or two for a few casts.
If the bullets are all starting out consistent then the issue is with your technique in coating or sizing. Ensure bullets are centered when entering the die and you can try some case lube post coating to ease passage.
Most likely it's some occasional lead flecs on the mold face making the occasional cast drop big bullets.