yet another 9mm leading thread

[asmith80]

First off, let me start by saying I have read through a whole bunch of 9mm leading threads and I've checked a few things first to try to solve this on my own.

Some stats:

I'm shooting a CZ SP01 that has been throated by DougGuy
Barrel slugged at .3555 and I'm shooting cast that has been sized to .358
I'm using Hi-Tek coating. This is the second batch I've done with this and the first batch gave me no issues. This batch also passed the wipe and smash test, so as far as I can tell, the coating was properly applied.
I pulled loaded rounds and the boolits all still measure at .358, so they are not being swaged down by the case or crimp (using Lee taper crimp die)
Alloy is COWW, and I think is around bhn 13 or 14
Using VV N320 powder and the load is right in the middle of the scale, so not too hot, not too light. Same load I've used for commercially cast lead and also had no issues in the past.

This is what the barrel looks like after about 20 rounds. I ran a wet patch followed by a dry patch through it just to make sure there was no carbon fouling to muddy the results. Also I now know how hard it is to get a decent picture down a barrel using a cell phone

[DerekP Houston]

Watching with interest to see the results, you've covered the bases I would've suggested to check.

[Smk SHoe]

Not sure if trying sized to .357 would help. Is it a new barrel? could it be a rough barrel and needs some shooting to smooth out any machine marks? Other than those idea's I think you covered anything I could come up with.

[asmith80]

It's not a new barrel, I've put maybe 1000 rnds through it previous to this.

It's got me totally stumped, too.

The only thing I can think of that's different from the last batch is that these didn't age as long. I cast these up Sunday and shot them today. The other batch sat for about 2 weeks

[asmith80]

Also, just looking over my targets from today, it looks like I had one round that struck the paper sideways. Not sure what that signifies

[Beef15]

Not much help, they will get harder to an extent as they sit after baking. Tumbling is often a side effect of severe leading. Curious to see what it is.

Sent from my SM-G360V using Tapatalk

[Thumbcocker]

My CZ75 BD loves the Lee 125rnfp over power pistol. Boolit is sized .358 cast of WDWW and lubed with Ben's red. Doug throated my barrel. No leading.

[meotai]

Is your boolit's base flat? or beveled?

My 358-155-TC Elco bevel base leads badly in my stock glock 17 barrel. But my 359-140 flat base from MP molds doesn't. Same 10 BHN, same amt of titegroup going 850ish fps, same 2 coats of hitek. So idk if bevel-base vs flat-base plays a factor or the .358 vs .359 diameter.

[gnostic]

I had leading issues with my CZ75 when I tried BLL. When I went back to Super Moly, the leading completely went away. The same batch of bullets with BLL shot flawlessly in models 19 and 686.

[asmith80]

I'm actually shooting both the TC ELCO and the 358-135 FN from NOE. In fact, I shot both today. Maybe I'll try again with just one or the other to see if that's a problem.

Gnostic, I'll try my m&p just to see if that changes anything. I'd really hate for it to be the CZs fault. Wanting to shoot that pistol is the whole reason I got into casting in the first place

[17nut]

Is it the Lee 124gr tumble lube bullet?
Notorious for leading.

[asmith80]

Went out to the range for some more testing today. Brought the SP01 and a Hi Power clone to get some more info.

Both barrels were cleaned before shooting. I first tried the 135gr. boolits and got leading in both pistols. Cleaned both again and tried the 155 gr. and still got leading in both. I shot 10 rounds of each boolit in both guns and the leading was as bad in the pic from my first post.

Got home and tried the wipe and smash test again on each boolit from this batch, just in case I had a fluke with the last one and they both passed.

Checked the bhn for each boolit since I remember using some different lead when I cast them up. 135 gr. was measuring 9.8 bhn on my Lee tester. This one was cast with range scrap. The 155 gr. came in at 13.4 and was cast with COWWs.

So it doesn't seem hardness of the alloy or boolit design are contributing to this. The only other thing I can think of is that I was using the same powder for both loads. 3.6 gr. of N320 in the 155 gr. loads and 4.0 gr. of N320 in the 135 gr. loads. I don't have a chronograph, so I'm not sure what velocities these are at, but both loads were right in the middle of the ladder with a good .3-.5 gr. buffer until I got to the max load for either.

The only other thing I can think to do is try a different powder. I've got Clays, Unique and Bullseye. I'll load some up and see if that is the culprit

[DerekP Houston]

You might try pinging Ausglock for his hitek expertise, perhaps he could recommend something the rest of us have missed.

[TexasGrunt]

I'm having a problem with 9mm leading with a different Hi-Tek coated bullet. Same alloy, same coating in 10mm, driven harder doesn't lead a bit.

As soon as I can I'm going to try a different bullet shape in the 9 and see if it makes a difference.

[asmith80]

Let me know what you find

[Larry Gibson]

OP doesn't state what the throats measure(?). Bullet at .358 and if throat is not .358+ then the Hi-tech is probably getting scraped off. I suggest sizing at .356 for that .3555 barrel. N320 shouldn't be the cause of the leading.

[asmith80]

ETA: just checked the pm DougGuy sent when he throated this barrel and he said his cutter was getting a little worn and he wasn't sure .358 bullets would work, but .357 should be fine. Wish I had remembered to look at this earlier. I've loaded up 20 sized to. 357 and 20 at .356 with the N320 loads. If I can get to the range tomorrow, we'll see if that works

[Ausglock]

FYI... I supply a large indoor range here in OZ.
Their shooting gallery loaner guns are CZ Sp01's
I make 135gn RN with 2 coats of Kryptonite green sized .357.
Alloy is 2,6,92 16BHN Hardball.
Zero leading.
When sized .356 or .358. Severe leading.
These are only loaded to middle of the range velocities to make Minor power factor (around 1000fps)
The 135RN is a grooveless bullet.

[gnostic]

I'm actually shooting both the TC ELCO and the 358-135 FN from NOE. In fact, I shot both today. Maybe I'll try again with just one or the other to see if that's a problem.

Gnostic, I'll try my m&p just to see if that changes anything. I'd really hate for it to be the CZs fault. Wanting to shoot that pistol is the whole reason I got into casting in the first place

The 9mm seems harder on lube than the 38 special at least in my guns. I've had similar leading, from one end to the other, until I added more LLA. After adding Alox on the second lubbing, my barrel was still leaded but all at the muzzle.

[asmith80]

Another update. Got to the range this morning and took some of the 155gr. rounds that I sized to .357 and .356 and loaded with the N320 load. I took the SP01 and it's little brother the P01 just to see if it was all my CZ pistols that were giving me problems. 10 rounds in each pistol.

Both the .357 and .356 rounds gave me leading like earlier in both pistols. Needless to say, this is frustrating me at this point.

Here's where things get unexpected. I also took some rounds I had loaded up with Unique. These had not been resized, so they were at .358. After 10 rounds through each gun, I had very minimal leading. A fraction of the amount I had with the rounds I had loaded with N320 regardless of the size of the bullet.

I feel like if I sized to .357 or .356 with Unique at this point my leading problems may go away. I'm going to load up another round of tests and see.

The thing is, I feel like I haven't actually solved my problem. All things being equal, the powder, coating, alloy, etc. etc. shouldn't have given me problems. I've got the sneaking suspicion that instead of solving my root issue I've just found something that will allow me to compensate for whatever it is I'm really doing wrong, and that doesn't sit well with me.

But who knows, I may load up this next batch of tests and have all my issues all over again