Learned a few new things today.

OverUnder725

OverUnder725

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I have been having issues with leading in my 9mm and have a post going in the reloading section looking at what may be going on. Of coarse, bullet size enter the discussion and I ended up measuring the bullets I had sized. I found that there is a something called a spring back effect when sizing cast bullets. All of the bullets I have been sizing for my 9mm are actually turning out to be .001" larger than the advertised size on the die. Some speculate that the harder the alloy being sized the greater the spring back effect. Some also suspect that the die itself contributes by being slightly "sprung out" in diameter as the lead bullet is forced into the die. Now, I measured the bullets of same composition that are 158gr SWC and some that are 340r RN and I found that the sized bullets were only .0005" over advertised die size. There is probably more to it than I understand but I thought it was interesting.
 
lead bullets are interesting, they like to be at least 1 though oversized if not 2 thou, this makes for a good seal in the barrel to prevent leading, another interesting little tid bit is speed, you have to keep the speed down in order to prevent leading in the barrel as well, the hardness of the lead and presence of a gas check or plain base will almost certainly dictate the maximum velocity for the bullet
 
yodave said:
lead bullets are interesting, they like to be at least 1 though oversized if not 2 thou, this makes for a good seal in the barrel to prevent leading, another interesting little tid bit is speed, you have to keep the speed down in order to prevent leading in the barrel as well, the hardness of the lead and presence of a gas check or plain base will almost certainly dictate the maximum velocity for the bullet
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I discovered from measuring the sized bullets that they were turning out larger than I had expected thus creating a bullet to large for the application. I have an add on EE right now looking for a .355" sizing die with hopes that it will produce a .356" bullet for me. I was sizing at .356" which was actually giving me a .357" bullet in my barrel that slugged .3555". I know that should be doable but I'm still having leading issues at .2gr increments of Bullseye from 3.4gr to 4.4gr with 125gr TC bullets so I'm not sure if speed is an issue. I will have to put them over the chrony.
 
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The pics I posted on other thread are of barrel that has only shot berry's fmj and looks like barrel I have shot Pc 9mm sized at .358

I don't get any leading.

Do you notice and blue color from Pc after cleaning?
 
OverUnder725 said:
I have been having issues with leading in my 9mm and have a post going in the reloading section looking at what may be going on. Of coarse, bullet size enter the discussion and I ended up measuring the bullets I had sized. I found that there is a something called a spring back effect when sizing cast bullets. All of the bullets I have been sizing for my 9mm are actually turning out to be .001" larger than the advertised size on the die. Some speculate that the harder the alloy being sized the greater the spring back effect. Some also suspect that the die itself contributes by being slightly "sprung out" in diameter as the lead bullet is forced into the die. Now, I measured the bullets of same composition that are 158gr SWC and some that are 340r RN and I found that the sized bullets were only .0005" over advertised die size. There is probably more to it than I understand but I thought it was interesting.
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I found with my rifle bullets that I PC if I don't bell the case enough it will cut through the coating when bullets are seated. This would allow bare lead to contact the barrel likely causing leading.
Rodney
 
How long are you curing your bullets for, if you smack it with a hammer do you get flakes coming off?

When i pc my pc usually adds .002 to .003 to he cast bullet, i would measure the cast bullet and then again after pc.
 
Usually powder coating does protect the lead, but just a though range scrape is usually near pure lead. If you have a lite powder coat and pushing fast than 650fps(which you probably are being 9mm) pure lead, will lead like crazy beyond that speed. Lots of guys like to put thick or multiple coats of the PC. I usually save soft lead for my black powder or slow 38, or 44. Lastly sorry did not view the picture, but lead bullets will usually always leave traces of lead. Don't over judge small amounts, my Beretta 92S always has small amounts of leading, which I don't scrub clean but the leading does not cake up either after lots of rounds, just kind of sits at par. I have an old 44 with lots of pitting it leads but the accuracy is bang on, even after 500rounds.
 
your throat size compared to boolit dia. is what can give you leading. Use .358 dia. boolits in 9mm, it works for me. The worst leading I have ever seen was the result of swaged lead boolits at .356 (commercial) in 9mm para.
 
f55 said:
How long are you curing your bullets for, if you smack it with a hammer do you get flakes coming off?

When i pc my pc usually adds .002 to .003 to he cast bullet, i would measure the cast bullet and then again after pc.
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I cast them on Friday, coated them on Saturday, loaded and shot on Sunday.

Here are some pictures of something I tried and one I hammered. Loaded three rounds with primer only and fired them. Left to right is .357", .358" and .359" as measured after sizing. Not sure if it has much bearing on anything but I was just curious as to actually how tight things fit at different sizes.



 
It looks to me as though you have to much lead exposed, the pc is coming off to easily. I would cure for longer (15 min) and measure bullets before and after coating to make sure its pc thick enough.

Is this tool blue pc?
 
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