Sizing after coating results in undersized bullet?

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totaldla

New member
So I shoot nothing but HiTek coated bullets nowadays. One supplier's bullets never shoot that clean, depositing gunk and lead - but it isn't more than annoying. I measure their product and it is exactly as it should - as best my calipers can resolve.

My question has to do with the coating process. Do you size THEN coat? To do the reverse seems like it would result in a bullet dependent on the coating to seal the bore, instead of the lead.
 
U

Unclenick

Staff
Size first. Let the barrel final size the resulting coated bullet. If you find the coating is shearing off (recover some from the backstop), try sizing a thousandth smaller, test again. Repeat until the problem is solved.

Some throats are easier on the coatings than others.
 
T

totaldla

New member
I saw this problem first with my 40sw loads. I was having what appeared to be classic lube failure (leading at the muzzle) . It seemed as though the coating was burning off.

A bit ago I was working with some HiTek coated 44mag fodder from two different vendors. Both bullets were .430" (within the limits of my calipers). One leads a little bit and the other shoots clean as a whistle. The one that shoots clean has a rough finish - pretty sure it was not sized after coating. The one that leads is pretty smoothe.

I know that there are other variables, but this isn't my first rodeo when it comes to diagnosing barrel leading. But I am kinda new to using HiTek coated bullets (9mm,40sw,44mag) and I'm wondering if bullet vendors aren't making a basic mistake when they coat and then resize.
 
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mehavey

New member
If the as-cast diameter isn't too far off (say ≤1-thou over), I'll size after coating.
If way over... (2-thou+), I'll size/then coat/size again.
Never had a problem out through 34" barrels under 2,000fps.

(This applies to conventional Eastwood PC)
 
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Unclenick

Staff
I am wondering if sizing post-coating is corrupting the bond between the powder and the metal. Also wondering if putting them back in the oven after sizing would fix that. It also might be interesting to size the bullet with unset powder on it do drive some powder particles into the bullet surface, then re-powdering before final oven treatment. There are a number of permutations of the procedure that could be tried.
 
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mehavey

New member
I've always sized after PC is cured, and driven those bullets as high as 2,500fps in the 16" AR.
If there's leading, the shooter didn't cure correctly/completely.:mad:
 
U

Unclenick

Staff
I also wondered about the curing situation. In a larger oven without a convection fan, uniformity of the temperature could be an issue. Mold release contamination is another possible issue.
 
R

res45

New member
I very rarely ever size bullets before coating rifle or pistol. Except for HP pistol bullets or rifle bullets that I want to get some expansion with, I water quench all my powder coated bullet right out of the toaster over gas check if needed and size accordingly. Leading was never an issue before or after I started using PC.

On the rare occasion that I have to size a bullet before coating and I have to use some form of lube I wash my bullets in 100% pure acetone before applying the PC which I get at the local dollar store in the form of fingernail polish remover. Never had any issues with the PC not bonding to the bullets before or after sizing.

If you don't have a convection oven, you can line the bottom of your toaster oven with lava rock or ceramic briquettes to distribute the heat more evenly.
 
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mehavey

New member
postscript/op cit/previous post(s).

While Lee says to lube lead bullets before sizing to prevent galling, I find I don't have to.

I keep the sizing die clean and the bullets* come out ready for shaking in standard
Tupperware container with a bed of airsoft beads as static-builder/transfer agent.

No problemmo.




* IF they need pre-sizing
 
R

reddog81

New member
You should be able to coat then size without issue. If you’re getting leading, the process used to coat the bullet was done wrong and it has nothing to do with when the bullet was sized.

You can size then coat but in theory sizing afterwards should be more uniform.
 
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