Glock barrel leading

[Bashby]

I’ve been casting boolits for my Polymer 80 with a (Edit to add not a factory Glock barrel like I thought) 9mm barrel. Barrel slugs to .3555. Been sizing to .357 with a Lee push through and powder coating. My lead is range scrap. I guess I need to try a harder alloy. I have some pewter and some Superhard from Rotometals. I’m new to casting and this will be my first time making a new alloy. Looking for advice on how much of what to add and best way to do it... or anything else that I should try.

[cwlongshot]

I would Look to your powder coat first. I shoot more cast thru my G35 than most folks. Some weeks see near 1000 rounds. All my cast and Powder coated. ZERO FOULING. That’s thru factory and KKM barrels.
Cast softer than most. 10bhn or less. Shooting loss from 800-1200 FPS.

You may need more baking time also are you quenching in water out of oven to cool
Or just air cooling?

One of the best ways to soften a billet is to heat to 400 for 20 minutes and air cool.

CW

[Burnt Fingers]

It's likely your barrel throat or lack thereof.

[sigep1764]

Pull a seated boolit from a loaded round. Measure the base diameter. I bet its getting swaged down by the brass case not being opened up enough.

[Bashby]

I would Look to your powder coat first. I shoot more cast thru my G35 than most folks. Some weeks see near 1000 rounds. All my cast and Powder coated. ZERO FOULING. That’s thru factory and KKM barrels.
Cast softer than most. 10bhn or less. Shooting loss from 800-1200 FPS.

You may need more baking time also are you quenching in water out of oven to cool
Or just air cooling?

One of the best ways to soften a billet is to heat to 400 for 20 minutes and air cool.

CW

Air cooling

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[Bashby]

It's likely your barrel throat or lack thereof.

I sent my barrel to Dougguy to open throat. Here are his comments.
This barrel had a really long weird tapered throat that was probably .600" in length before the rifling, it started at .357" and went smaller, I almost couldn't fit a pilot into it to center the reamer because it was so long. I took out the taper, and took the 1 degree leade in all the way to the lands. It has a long .358" freebore in it that's pretty much parallel before the rifling, this will not hurt anything in fact it will hold a .358" concentric and square to the center of the bore all the way to the leade ins, and could improve groups noticeably. The long tapered throat cannot center the boolit very well, as the diameter keeps changing, this would allow the boolit to fall into alignment wherever it met the least resistance and then stay that way so if it was off axis at all, the throat wouldn't correct it. Hopefully it will work well with .358" for you.

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[Bashby]

Pull a seated boolit from a loaded round. Measure the base diameter. I bet its getting swaged down by the brass case not being opened up enough.

Pulled one the other day and it measured .357. I am using 38 s&w expander.

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[cwlongshot]

Will a .358 chamber?

Also powder coat smash test tell a little bit not the whole story. For instance. My buddy shoots quite a few of my bullets into wet pac papers. Soft billets seem to always shed the PC more than hard cast. So to My mind the powder is doing the same job but the bullet surface is failing the adhesion.

How are you baking and have you used any accurate instruments to prove actual temperature?

CW

[Bashby]

Haven't tried to chamber a 358, I'm sure it would with the work Doug did.

I'm using one coat of Smokes PC. I could have got a thicker coat on some of my last batch. Plan to shake longer on my next batch.
I am baking at 400 for 20 min in a toaster oven. Have not verified temp.
I did a smash test on one of my 105 gr SWC and it seemed to be good to my untrained eye.
My mold is from accurate. I don't remember specs. Will look when I get home.

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[gloob]

I use .358 bullets in my stock Glocks. They fit several Glock 9mm barrels. I found the competition 5" long glock 9mm barrel has a shorter throat than the regular ones. I suppose this is the "match chamber." It still chambers the .358 bullets, but it can't chamber as oversize of an OAL; the bullets have to be seated slightly deeper, closer to normal 9mm specs.

Bashby, this thread is confusing because the title refers to leading, but in the thread you seem more concerned with accuracy and have not mentioned anything about leading. Did you solve the leading problem with the .358 bullets, using the 38 S&W expander? This combo was a major improvement for me (I'm assuming you are referring to Lee dies), but still not quite enough. And the effect of case swaging at the base of the bullet was very subtle. Just 2 thous or so, and only at the very base-end of the bullet, leaving full diameter in other parts of the driving band; so this was nothing, right? When I got the even larger and longer NOE 356/360 expander, I achieved perfection. Accuracy is great, and I have not cleaned my bore ever since.

I've shot .356 commercial cast using this expander, too. That's almost perfect, but still a tiny bit of leading (only a little bit near the chamber, which would be awesome, except I already have perfection to compare it to). So .358 it is, for me.

Another example: in 40, I bought the largest expander that I could buy at that time (if memory serves, that was 398, Lyman M Die. Although I have discovered that NOE has since that time started making one at .400"). Shooting WW cast, this left full bore, 1-2 mm thickness lead fouling along the entire bore of my Glock in just a single shot. That was the only shot I fired in that gun that day. After making a 401 expander, I have this gun shooting perfectly clean and accurate using the same and also commercial 401 cast bullets.

Don't underestimate case-swaging!

*edited: also, if you get the bullet to completely fill the bore and the case mouth to nicely seal the chamber on firing? Regular cast bullets make no smoke in a locked breech gun. Even rapid fire at an indoor range, I can't notice any difference in smoke from commercial jacketed ammo. So if you are lucky and get it right, there's not much reason to do coatings, other than coatings making the ammo probably work better in other guns which you will own or shoot in the future. So I wouldn't suggest you don't bother powdercoating. That is fun in itself, not work; if that's your thing. But if you're after accuracy, it doesn't hurt to get all the other important details correct, either.

[cwlongshot]

You should try to “shake it soft” off as much powder as you can. You should NOT need a second coat. If your not getting full even coats you have other issues somewhere. Smokes is good stuff.

Get a good thermometer. I’ll bet ya your temp isn’t where ya think. I have used a few ovens none have been accurate. My first one left puddles where my bullets used ya be.

CW

[Bashby]

[Bashby]

[Bashby]

I use .358 bullets in my stock Glocks. They fit several Glock 9mm barrels. I found the competition 5" long glock 9mm barrel has a shorter throat than the regular ones. I suppose this is the "match chamber." It still chambers the .358 bullets, but it can't chamber as oversize of an OAL; the bullets have to be seated slightly deeper, closer to normal 9mm specs.

Have you slugged your barrel(s)? I figured .0015 bigger than my bore should be plenty

Bashby, this thread is confusing because the title refers to leading, but in the thread you seem more concerned with accuracy and have not mentioned anything about leading.
I don’t think I said anything about accuracy. I said I purchased my mold from Accurate.

Did you solve the leading problem with the .358 bullets, using the 38 S&W expander? This combo was a major improvement for me (I'm assuming you are referring to Lee dies), but still not quite enough. And the effect of case swaging at the base of the bullet was very subtle. Just 2 thous or so, and only at the very base-end of the bullet, leaving full diameter in other parts of the driving band; so this was nothing, right? When I got the even larger and longer NOE 356/360 expander, I achieved perfection. Accuracy is great, and I have not cleaned my bore ever since.

I have not tried sizing to .358

I've shot .356 commercial cast using this expander, too. That's almost perfect, but still a tiny bit of leading (only a little bit near the chamber, which would be awesome, except I already have perfection to compare it to). So .358 it is, for me.

Another example: in 40, I bought the largest expander that I could buy at that time (if memory serves, that was 398, Lyman M Die. Although I have discovered that NOE has since that time started making one at .400"). Shooting WW cast, this left full bore, 1-2 mm thickness lead fouling along the entire bore of my Glock in just a single shot. That was the only shot I fired in that gun that day. After making a 401 expander, I have this gun shooting perfectly clean and accurate using the same and also commercial 401 cast bullets.

Don't underestimate case-swaging!

*edited: also, if you get the bullet to completely fill the bore and the case mouth to nicely seal the chamber on firing? Regular cast bullets make no smoke in a locked breech gun. Even rapid fire at an indoor range, I can't notice any difference in smoke from commercial jacketed ammo. So if you are lucky and get it right, there's not much reason to do coatings, other than coatings making the ammo probably work better in other guns which you will own or shoot in the future. So I wouldn't suggest you don't bother powdercoating. That is fun in itself, not work; if that's your thing. But if you're after accuracy, it doesn't hurt to get all the other important details correct, either.

......

[Bashby]

You should try to “shake it soft” off as much powder as you can. You should NOT need a second coat. If your not getting full even coats you have other issues somewhere. Smokes is good stuff.

Get a good thermometer. I’ll bet ya your temp isn’t where ya think. I have used a few ovens none have been accurate. My first one left puddles where my bullets used ya be.

CW

I get spots of PC on the foil on my tray, but definitely not puddling. I had an oven thermometer but I couldn’t find it last time I looked. I have my lead thermometer but I don’t think it’s made to put the whole thing in the oven.

[Plate plinker]

My PC is still on the frag after impacting steel. Just saying.......

The PC thing is another animal than what we did before.

[slide]

Bashby, check out the A.t.M. thread. It is an inexpensive way to check your temp. What you are needing is the temp of the bullets. If I can help please don't hesitate! We are all in this together!

[DougGuy]

So, you are still getting leading correct? You have not yet sized to .358" correct?

You should have great groups and no leading if you are sizing so they will just plunk in the throat.

Also, one of the things you can count on a soft alloy to do, is to obturate once pressure from firing builds up enough in the barrel, if you are too hard for this to happen, then gas is likely escaping along the sides of the boolit if you are not sized to the throat.

[Bashby]

So, you are still getting leading correct? You have not yet sized to .358" correct?

You should have great groups and no leading if you are sizing so they will just plunk in the throat.

Also, one of the things you can count on a soft alloy to do, is to obturate once pressure from firing builds up enough in the barrel, if you are too hard for this to happen, then gas is likely escaping along the sides of the boolit if you are not sized to the throat.

Thanks for chiming in Doug, hope all is well with you!
Yes, I am getting leading. I have been sizing to .357 even though I had you size the throat at 358. It’s starting to look like that may be my problem. I am still learning. I figured 357 would be best since my barrel is .3555. I did not know the bigger throat would be a problem. It makes sense now that I think about it. I have 358 sizing dies.

[gloob]

I did not slug any of my bores. In my experience, it doesn't really matter how big the bore is UNTIL you have put the biggest available/practical bullet in there that will still chamber. In a locked breech pistol or a revolver, it doesn't matter if this is even 2-3 full thous larger than bore diameter, AFAIK and have read. (In a blowback, you have to be more careful). The simplest way to think about it is I want to fill the freebore as much as possible to limit gas cutting around the bullet prior to the bullet squeezing into the rifling.

You also, for some mysterious reason, have to care about case swaging of the base of the bullet; this case swaging is largely a problem in cartridges with thick/stiff brass. I have had it in 9mm and 40SW, personally. You can prevent case swaging by using harder alloys (but then you get antimony fouling), or you can do this with a large enough expander. The effect of even a small amount of case swaging can be enormous using a soft bullet in a Glock. Something to do with the leade being so long/gradual, perhaps, which allows more gas cutting compared to other barrels. I honestly don't know. But the base of the bullet seems to be a very important ingredient in this case. Maybe something to do with fluid dynamics on the gas cutting; a smaller base might allow more flow around the bullet and/or an asymmetrically squeezed down base might direct/focus that flow over one spot on the bullet, resulting in more serious melting/vaporization. Think of porting an engine, rounding entry points over, in order to improve laminar flow and increase throughput. And/or the full diameter flat base might be important for proper/optimal obturation? I honestly don't know; i just know it can make a big difference.

If I had done the above and STILL get fouling, then I would slug the bore and/or feel for restrictions. OTOH, if fouling is eliminated by doing the above, then I might try smaller bullets if I had a reason. Like maybe I own other guns with tighter chambers/freebores, and I want to see if I can use the same ammo in both.

If you get the powder coat thick enough, you can probably eliminate lead fouling that way, too. But in my experience with half a dozen Glocks, it is highly likely you can shoot even nekkid cast bullets without any fouling if you get the bullet big enough and you eliminate case-swaging. I have revolvers and other pistols with traditional rifling, and the only handguns I can shoot with zero fouling and the best accuracy with cast bullets (as good if not better than my best jacketed) are my Glocks. All of them.

This is what works for me. I might have gotten some things mixed up and incorrectly attributed. But I was pretty systematic and it took year or two to figure this all out.