Leading on top of lands

[tomme boy]

What would cause leading in top of the lands and not in the grove? I have a 9mm that is driving me crazy. I am sizing to 0.358" and the barrel is slugged at 0.3557" I did a pound cast of the throat and it is the same as the bore. I lapped the throat to smooth it up. It has a very long throat. About a 1/4" long by looking at it.

I pulled a few boolits from the brass and they are still 0.358" so the case is not swaging them down. I have tried two different alloys and both have done the same. One was about 18 and the other was about 12. The leading will show up on top of the lands with one 16 rd. magazine. I am NOT using a LFC die. I am just crimping enough to remove the belling. I have also used two different lubes. NRA 50/50 and RandyRats TAC1. I was thinking on trying the Tac1 and then tumble lubing in ALOX next to see if that works.

[MBTcustom]

Not that Im any expert, but i wonder if you might try sizing .3567? Sometimes less is more?

[white eagle]

does it come rite out or do you have to scrub it out
some times you can have what may appear to be leading which is in fact just a kinds wash that comes out easily

[338RemUltraMag]

I think that is antimonial wash, I get it in a few of my rifles and it never builds up and tends to "self clean" I have shot a few hundred rounds like that and can not see any build up.

[Cherokee]

Well Tomme, that's an odd one to me. I would be inclined to try the .357 as suggested above, or even .356 size and see what happens.

[tomme boy]

Forgot to add, I also tried sizing at 0.357" It is not antimony wash. I have to use bronze wool to get it out. I run a brush down first and I get a cloud of silver flakes when it pushes out the barrel. The throat is also kind of weird as it looks like a Weatherby as there is a little bit of freebore. There is nothing there. I think Glock barrels are the same way. This has ballard rifling not the polygonal. If I can't figure this one out it is going down the road.

[swheeler]

Barrel is rough on top of the lands, radial tool marks, shoot a few hundred jacketed through it or lap it.

[tomme boy]

Nope. They are very smooth. Would boolit skid do this?

[Shiloh]

Well Tomme, that's an odd one to me. I would be inclined to try the .357 as suggested above, or even .356 size and see what happens.

My guess is .356 will be to small. They may squirt out of the barrel. Heck, try it and see.

Shiloh

[swheeler]

I don't know. Try switching lubes?

[runfiverun]

I think you might just be blowing gas past the boolit getting gas cutting.
then the boolit is strong enough to scrape the grooves clean but noting is there to work on the bore.
you might want to try a bit more crimp, or a different powder.

[detox]

Mike Venturino's magic 9mm load consists of Linotype alloy, Winchester brass, Lyman 120 gr.356242 mould sized to .357, 4.0 grains of Bullseye, 4.4 grains of HP-38, 4.5 grains of Zip. He also likes Oregon Trail's .356 mail order 124gr round nose bullets. He states "neither of these two HARD bullets lead/foul significantly in my 9mm handguns". There was no mention of what lube was used
http://www.laser-cast.com/9mm.html

[detox]

You can polish the barrel a little more using 0000 fine steel wool wrapped around bore brush. I would also use Kroil or a fine oil to help cut or polish.

[JonB_in_Glencoe]

Forgot to add, I also tried sizing at 0.357" It is not antimony wash. I have to use bronze wool to get it out. I run a brush down first and I get a cloud of silver flakes when it pushes out the barrel. The throat is also kind of weird as it looks like a Weatherby as there is a little bit of freebore. There is nothing there. I think Glock barrels are the same way. This has ballard rifling not the polygonal. If I can't figure this one out it is going down the road.

Have you had success with loading/shooting 9mm in another gun ?
If so, that will point away from your technique and point toward the gun.
AND it sounds like you've tried most everything typically needed to solve the common problems of Lead fouling.
SO, I suspect your gun has an uncommon problem. Depending on the Gun, I'd either replace the barrel or sell the gun...OR just keep it as a jacketed bullet shooter.

[detox]

Yea, see if it will shoot Winchester jacketed ball ammo reliably and accurately. If not...i would sell gun.

The market is flooded with crappy 9mm automatics.

[tomme boy]

It shoots Jacketed fine. But that style of shooting is not affordable to me. That was why I started to cast in the first place.

[338RemUltraMag]

Does the leading build up? If it self cleans I would just deal with it. Load up 300 rounds shoot 50 at a time and see what happens, check the bore every 50 rounds. Have you slugged the throat? My M&P has the same kind of throat and it needs a 358 bullet. You may even need a 359 projectile, never know!