Can a PC bullet pass the hammer test and still not be properly cured?

Hello all,

I'm a noob at casting and PCing. As if you wouldn't have been able to tell. I've been casting/coating for a few weeks and have been completely happy. However, the other day I built a rubber mulch bullet trap to minimize lead loss and the captured bullets rasied a question. The bullets are missing their coating on about 85% of their bearing surface.

Research lead me to check some of my prepared bullets with the hammer test. They seemed to be fine. No flaking.

When shooting the PC bullets, I've always had a small amount of leading, starting at the chamber and tapering off to none at about halfway down the barrel.

I don't have a barrel slug kit, but I did push a coated bullet through with a wood dowel. The grooves appear to measure .357. Since I use the Lee 356-125-2r then PC, then size to .356, I'm wondering if the cause is too small of bullet.

Here's some more info that may be pertinent.
scrap junk lead - I didn't think hardness mattered with PC so I've been using anything I can find. Is this assumption wrong? I do water quench when casting.

Gun is a Taurus PT 92 AFS-D

PC is HF red - I know. I know. I will get better powder, but this was just to get me started, and I thought everything was fine until I recovered those bullets with missing coating. :D

No signs of bullet tumbling and accuracy is only slightly lower than FMJ. 2 1/2" groups for PC cast, and 1 1/2" groups for FMJ from 7yrds offhand. I'm just getting back into shooting if that sounds horrible.

Thank you for your input.

Also, when I used that bullet as a makeshift barrel slug, it was PCed and the lands removed the coating. It was intact at the grooves. Which also leads me to think it is on the small size.

Also forgot to mention, my PC method is to preheat, then tumble, then 400 for 18min. This shortening of the time is what had originally made me think the PC wasn't fully cured. Haven't had a chance to double check the temp yet.

Are your barrels leading? if no, the PC is doing it's job.

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Originally Posted by NyFirefighter357

Are your barrels leading? if no, the PC is doing it's job.

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Correct. The purpose of lubing bullets (and that includes PC) is to prevent leading. If you have little or no leading, your PC is working.

Next: How's your accuracy? An undersized bullet may not shoot accuracy. But if you're getting acceptable accuracy and what leading you get is manageable, go worry about something else -- your powder coating is fine.

Yes, a small amount that starts at the chamber, then tapers to nothing about halfway down the barrel.
I didn't consider it a big deal, but I hear these stories about everyone else getting no leading at all. Also seeing other's pics of recovered bullets with full coatings intact made me a little nervous I was doing something wrong.

Increase finished size .001 to .002
Should stop all the leading and increase accuracy

Try sizing to .357 and install a gas check after powder coating. The 9 is sometimes hard to find a properly fitting bullet. Load the 357 SIG which is actually a 9 mm with the same cast bullet used in light loads for 38 Special all are sized to .357 and a home made gas check is installed.
All are powder coated also.

Are you certain you have leading in the barrel or, does it just 'look like' leading? Or look like an antimonial smear, a light grey smooth streaks?

At first when I was a neophyte at PC'ing...I trusted my oven dial, it said 400*F. so I believed it. I got some long medium light grey streaks in the grooves of the barrel. I scrubbed it with everything I had, no affect, even tried acetone...some came out but lots stayed there. They were thin and absolutely smooth streaks, almost looked like a color difference in the steel of the barrel.

Long story shortened...it was uncured PC, yes they passed the hammer test flat as a nickel and the PC stayed on...it was the oven was only coming up to 325*F. or so, it wasn't cured properly. That's when I got a thermometer and started using that, now that cheap Chinese convection oven can't lie any more!

the Taurus's want 358 coated or uncoated.

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Originally Posted by runfiverun

the Taurus's want 358 coated or uncoated.

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My Taurus .357 wheelgun is as You say. 358 is exactly what it likes. Anything under that accuracy suffers and some leading on my traditional check and lube boolits. Pc'd boolits seem to not lead ,but groups open up pretty good.- CASTER

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Originally Posted by OS OK

Are you certain you have leading in the barrel or, does it just 'look like' leading? Or look like an antimonial smear, a light grey smooth streaks?

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No, I'm not certain that it is lead. I'm not really sure of anything being a rookie.

I did check the oven temp and it does seem likely that they were under cured. The oven was getting to 400 degrees, but for only a small portion of the time they were in.

So, I put a second coat of HF red on, and bake for the full twenty while confirming the temp. This step bumped the size up to .3575(average) and hopefully cured them properly. The new bullets also passed the hammer test.

I slugged the barrel again with one of these new bullets and more of the coating stayed on than with previous attempts.

I'm going to load up some test rounds, but it will probably be Fri or Sat before I get to try them.

Thank you everyone for your advice.

Remember, cook time is after the powder starts to flow. A bit longer won't hurt,less is a mess...

i think they can pass the hammer test , and still not be cured good .

i say this only because,
i cooked mine at what i thought was 350 degrees for 20 minutes (after 10 minutes warm up)
and had the paint flaking off (if you pick at it.)
it is a convection oven.
i discovered that temp was running about 290 at best....now days i warm it up and set it for 450 degrees and it temps out at about 375 or 380.

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Originally Posted by mozeppa

i think they can pass the hammer test , and still not be cured good .

i say this only because,
i cooked mine at what i thought was 350 degrees for 20 minutes (after 10 minutes warm up)
and had the paint flaking off (if you pick at it.)
it is a convection oven.
i discovered that temp was running about 290 at best....now days i warm it up and set it for 450 degrees and it temps out at about 375 or 380.

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This is why I drilled a hole in the side of my toaster oven and added a thermocouple for my PID. I had too many temp varations trusting the dial. Now I just put it on max heat/on and let the PID cycle it on off as needed. I preheat for a good 20 minutes prior to baking anything as well. Might be a waste of electricity but I've had much more consistent results since I started doing this.

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Originally Posted by DerekP Houston

This is why I drilled a hole in the side of my toaster oven and added a thermocouple for my PID. I had too many temp varations trusting the dial. Now I just put it on max heat/on and let the PID cycle it on off as needed. I preheat for a good 20 minutes prior to baking anything as well. Might be a waste of electricity but I've had much more consistent results since I started doing this.

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That is a very good idea. Run it like a lead pot!

Time for my second PID I guess... Oh wait, I want convection this second time around.

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Originally Posted by Stilly

That is a very good idea. Run it like a lead pot!

Time for my second PID I guess... Oh wait, I want convection this second time around.

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I should really get a second one built, but I just swap the plug for the TC and let it learn the temp for 30 minutes before starting. When I get around to coating I'll do multiple batches so it takes most of the day doing 2-3 coats of hitek. Cast in bulk, then coat in bulk. Works for me.

Not as good as a PID but I found an oven thermometer for $4.00 at Wally World. I don't use it every run but did the first few to compare the setting to the measured temp. The convection oven has a digital readout so it's easy to replicate the set temperature that hits 400 internally.

I haven't found the need for a gas check on a PC pistol bullet yet. That's everything from .380 to 500 S&W at over 30,000 psi.

I'm also finding that being at groove diameter is sufficient. Being under is still a no no. Being a little over is still as good as it ever was. ;)

Motor