What happens if soft lead and many layers of PC are used? answer inside

[nueces5]

This time I tried to save linotype
I bought a few range lead ingots, which gave a hardness of 8 bhn. I've been wanting to do this test for a long time.
A friend has a company that paints large metal structures, such as pipes, etc.
So he has a large assortment of electrostatic paints.
He gave me a couple of sample bags, which he considers to be tougher and easily form a thick layer.
So I made a batch of boolits with the MP 135 RNFP mould, I did 4 coats of paint, trying to make them pretty thick.
Then I passed them through the 356 sizing and loaded them, and the first shots showed keyholing, no lead accumulation in the barrel.
The next experiment will be with the addition of very little linotype, bringing the hardness to 10 bhn.

[sigep1764]

My suggestion would be sizing to 358. 356 is very commonly too small for 9mm bores.

[Meatpuppet]

Ditto on the sizing to 358, especially if you are going to increase the hardness. I have gone to .358 for all of my 9MM reloading with coated projectiles (home rolled or commercial). The fired projectile will swage down without a problem, but an undersized projectile will almost never "swage up". My friend's SIG Legion competition gun will keyhole horribly with 147gr .356 coated rounds, but is an absolute tack driver with the same brand 147gr .358 coated rounds.

Why so many layers of PC?

[charlie b]

I agree, why the many layers of PC? Just use one layer. Soft lead, hard lead, doesn't matter much. Size to your groove dia.

What does matter is the throat on your barrel.

[wilecoyote]

...to use soft lead and sparing linotype, if feasible.
(many layers of PC should protect better from leading, I suppose_
I don't PC, but I asked myself how far in alloy softness could I go,
using gas checks but, again,with as little or no linotype or tin, as possible).

[Meatpuppet]

Lots going on here. Based on my experience:

If you PC your cast boolits you can pretty much go as soft as you want with the BHN if you are 2500fps or less. I use pure lead with a little Tin for mold fill out for all my PC boolits now. If im using range scrap lead I will mix pure lead with it to keep the BHN low. I have no experience with PC above 2500fps, but members do it all the time. There are lots of companies producing PC boolits for high velocity rifles.

I understand that PC bonds with the boolit during curing, becoming a "bullet jacket" that is supported by the lead. Extra layers of PC simply bond to each other without becoming a bullet jacket, just becoming layers of coating without a hard sub-surface to bond to and provide support.

Extra layers of PC DO NOT prevent leading if the boolit is not the proper size for the barrel. Proper boolit fit is the single most important factor in preventing leading. The PC coating is essentially a lubricated jacket which does prevent leading as the bullet moves through the bore. However, it cant fix an improperly sized bullet allowing gas blowby, which will strip PC and lead off the boolit. I think a gas check will help an undersized boolit, but not fix it. I have not found that a gas check helps a properly sized and PC'd boolit and stopped using them with PC boolits altogether. Again, all of my PC boolits are used 2500fps or slower.

Regarding your Keyholing, do you know the twist of your barrel? As you go heavier than 147gr in 9mm, velocity and twist rate become a factor in bullet stability. I understand most manufacturers have moved to 1 in 10 twist that works well with a wide range of bullet weights and velocity.

I would try your original experiment with a .358 sized boolit and a single coat of PC to see what happens.

[nueces5]

When I bought the Lee sizing of 356, I used a small mandrel with 600 sandpaper, to enlarge it and I was at 0.3565
I have a die 358, but then it is difficult for it to enter the chamber. I've already tried.
The barrel is 356, and the boolits I do with 12 bhn, and a single PC layer work great without keyholing.
What I am trying is to lower the hardness of the lead until I see how much is enough.
I tried to replace that hardness with various layers of PC and that's what I wanted to show you.
I'll load up the new hardness 10 boolits today, and test them tomorrow if I have time.

[GregLaROCHE]

One coat has always been enough for me. However, my range scrap isn’t that soft. Still if your not going for max velocity, one coat should be enough. Boolit diameter is the first thing I would be experimenting with.

[charlie b]

...The barrel is 356, and the boolits I do with 12 bhn, and a single PC layer work great without keyholing....

Since one layer works then stay with one layer. Then use softer lead and see what happens.

Only change one thing at a time.

[skeet1]

I would just size lube and shoot.

[Meatpuppet]

Hmm. I reread your original post and last one. This is an interesting issue to resolve.

Your powdercoat, what brand is it? Other people have done all the legwork on powdercoating boolits and I just jumped on the bandwagon with Smoke 4320's PC (forum vendor) and never looked back. Someone with more knowledge may be able to explain what works and what does not work with powder brands.

What barrel manufacturer are you using if the .358 sized bullet will not chamber? What is your final overall length? I had to purchase a Manson Throat Reamer (not chamber reamer) for my CZ barrels to allow the porky, round ojive of the heavy 147gr and up 9mm bullet profile to reliably chamber at my desired OAL (Glocks and 2011 were not a problem). You should not have that problem with the MP 135 profile unless you are loading very long or have too many coats of PC.

What is your final crimp DIA? I have heard that severly over crimping can cause chambering issues and keyhole issues. After sizing the case with a U-die, I typically run .379 taper crimp with PC boolits and have no issues with setback or chambering. I'm loading on a progressive press and I do also use a Lee FCD at the last station (I can hear the howler monkey cries of rage!). The FCD did not affect my accuracy, but dropped my chambering issues to zero with all varieties of coated boolits.

For my 9mm uses (Action Pistol and Suppressed) absolute best accuracy was not my goal, but 100% reliability is. Like it or not, the Lee FCD works for me and my guns. Also, it resolved a chambering issue with 165gr loads into a suppressed PTR 9K (MP5 Clone), which supposedly have "tight" chambers and extremely short Throat.

Again, this is super interesting and I am looking forward to what the fix will be.

[Grayone]

One coat has always been enough for me. However, my range scrap isn’t that soft. Still if your not going for max velocity, one coat should be enough. Boolit diameter is the first thing I would be experimenting with.

I agree. One coat is good to go!

[popper]

for multiple PC coats, cook at lower temp till PC flows well. Last coat cook as normal. You want all layers to catalyze at the same time into one layer. Once you get to a thou or so thickness, you just add abrasion resistance, scuff off more before getting to lead. When I was doing ESPC I did some pretty heavy coats and found no difference.
I'm guessing the keyhole is from PC not holding the lands well.

[oley55]

Since one layer works then stay with one layer. Then use softer lead and see what happens.

Only change one thing at a time.

^^^^great suggestion. I just wish I could remember it. Perhaps I should post a great big sign in my reloading area..?

[Tracy]

Regarding your Keyholing, do you know the twist of your barrel? As you go heavier than 147gr in 9mm, velocity and twist rate become a factor in bullet stability. I understand most manufacturers have moved to 1 in 10 twist that works well with a wide range of bullet weights and velocity.

I don't know why barrel makers make 1:10" 9mm barrels now, but most .38 Special and .357 Mag barrels are 1:18.5". The standard bullet weight for .38 Special is right at the top end of what is usable in 9x19. .35 Whelen twist rates are 1:12" to 1:16", and even the 16 twist will stabilize a 280 grain 358009. I really doubt that twist rate is ever the cause of instability in 9mm, with any bullet weight that will fit and cycle.
My Blackhawk with 18.5" twist stabilizes 158 grain boolits just as well with the 9mm cylinder as it does with the .357 cylinder.

[Larry Gibson]

"I don't know why barrel makers make 1:10" 9mm barrels now,"

Back in the day when the standard twist was 1-16" in the 9mms someone tested faster twists in modeling clay and determined [assumed?] the faster twist, especially with expanding HPs, created a buzz-saw effect in the wound cavity creating better terminal effect. Sometime after reading how that would make the 9mm more lethal than a 45 ACP or even a 357 magnum I did a bit of "terminal effect" testing with 10" and 16" twist 9mms using SuperVel 90 HPs on live jack rabbits and rock chucks. I could not see any difference in the terminal effect with either twist. Perhaps if I had been hunting/shooting blocks of modeling clay.......

[Meatpuppet]

Larry, thats an interesting "twist" I never heard before. I was more concerned with stability of the long Ibejihead 165gr "mortar round" poking along at 750 fps and avoiding baffle strikes. The Berger Bullet Stability calculator showed I needed under a 1 in 20 twist at that velocity. The same calculator shows the Atlanta Arms, Army Marksmanship Unit Load of 115gr at 1200fps can take a 1 in 30 twist and still be stable. I know some of the Whiz-bang USPSA Open guns are using 1 in 32 twist with fantastic accuracy (of course they are pushing 1500fps +).

I'm always learning something new. Still looking forward to "the fix."

[jonp]

Since one layer works then stay with one layer. Then use softer lead and see what happens.

Only change one thing at a time.

When doing any experiment only change one thing at a time then move on. I talked recently with someone on here who said he doesn't pay much attention to BHN for target boolits when powdercoating. Cast's whatever and coats then sizes. I spent today casting ingots to clear up my melter and am going to give this a try with different BHN including straight PC using some of Smokes powdercoat I got a few weeks ago. Probably try 38sp WC first.

[jonp]

"I don't know why barrel makers make 1:10" 9mm barrels now,"

Back in the day when the standard twist was 1-16" in the 9mms someone tested faster twists in modeling clay and determined [assumed?] the faster twist, especially with expanding HPs, created a buzz-saw effect in the wound cavity creating better terminal effect. Sometime after reading how that would make the 9mm more lethal than a 45 ACP or even a 357 magnum I did a bit of "terminal effect" testing with 10" and 16" twist 9mms using SuperVel 90 HPs on live jack rabbits and rock chucks. I could not see any difference in the terminal effect with either twist. Perhaps if I had been hunting/shooting blocks of modeling clay.......

Can't say I've heard that before and the "buzzsaw effect" has me puzzled as I always thought it was either bullet performance or velocity that was the factor with, for me, bullet taking precedence at least in handguns. Twist never entered my mind. I wonder if whatever was allegedly found would show up better in ballistic gel as the wound cavity would be easy to see.

[charlie b]

^^^^great suggestion. I just wish I could remember it. Perhaps I should post a great big sign in my reloading area..?

And I wish I always followed my own advice

I can't count the times I tried to 'shortcut' the process, and then have to go back and repeat it properly.