9mm is getting heavy leading

[sammy]

Hello all,

I just got a new KKM barrel for my G19 and loaded up some Missouri 147g. LSWC's http://www.missouribullet.com/detail...ry=8&keywords= and need a bit of help. The load I am using is

147g. LSWC
3.1g. of Universal Clays
1.135 OAL
Tula Primer

Second group was the same but with 3.3g. of Universal Clays

I ran 10 of the 3.1g. loads first and WOW, these things were accurate. The disapointmet came when I looked down the barrel and found heavy leading 1/3 of the way down the barrel. This was the same result with both loads.

I brought another load that worked well. Not nearly as accurate but no leading at all.

122g. LSWC
4.0g. of 231
1.07oal
Tula primer

So what do you think? Could it be the powder? Keep in mind the start load is 3.0g. and the leading was the heaviest with the start load. I can only go up to 3.5g. of Universal but I am sure the result will be the same.

[Bill Steele]

There are a lot of different reasons for leading; one general condition I have found is when you are running a mismatch of hardness and charge leading can occur.

The harder the lead the more stout the charge and the softer the lead the lighter the charge.

That 231 load with the 122gr LSWC's looks pretty close to a start load level as well.

Knowing the Brinell hardnes of both bullets might help.

[cjskalka]

I have found with my home cast bullets and when I would buy commercial cast bullets that pushing them faster was better. I would get zero to little leading when pushed at the same velocity as fmj rounds. I shoot 125-130gr LRN out of my XD9 and push them with 4.0gr of titegroup. Use caution when increasing your powder charge but more often than anything else, this has been the solution to all of my barrel leading woes.

[sammy]

Thanks for the tips guys. I don't know the hardness of the bullets but the 122g. bullets are very low quality. I will try working my way up to max and see what happens. Universal is my first choice simply because I have lots of it. Next time out I will try 231 and Power Pistol. If higher velocity is what this bullet likes that should do the trick. Besides the Lyman book says that a max load of Power Pistol is the most accurate load of the ones tested in their universal 4" reciever.

[Bill Steele]

I would guess a slower powder like PP would probably be headng in the right direction if you want to pump things up a little and still keep things safe.

In my Lee book, he lists WAP and W571 on top of the totem pole for performance with a 147gr lead bullet. Both of these are substantially slower powders than PP which is a slower powder than either Universal Clays and W231.

[bruceflinch]

What brand of bullets, Sammy? 9mm? I have to wonder if the bullet shape might add to the issue.

[AJD]

Do you have the tools to slug your bore? If not do you know someone who does? I know many 9mm barrels actually have groove diameters larger than .356. I've heard of some factory barrels as high as .358. I'm not sure about the aftermarket kkm though. I believe the MB 9mm has a BNH of 18, which is quite hard. That's the same as what they have their .357 mag bullets rated at. It could be a combination of a bullet that's too hard and a bullet that is a little small in diameter. As mentioned using a hotter charge can help the bullet to obturate and seal the bore, but only to an extent.

[sammy]

What brand of bullets, Sammy? 9mm? I have to wonder if the bullet shape might add to the issue.

They are Missoui.

As far as slugging the barrel what is that? I guess Google is my friend here.