Leading and other issues?

[Idaho45guy]

Got a new KKM Precision 4.5" 10mm barrel for my G29 for my GSSF match next weekend.

I worked up various loads for it using .400 180 gr. Hornady XTPs and RCBS 180gr cast boolits. Originally had about half a pot of Lyman #2 then added some lead my dad gave me and filled the pot. He did not know the exact hardness of it, but said it should work fine...

Boolits are sized to .401 and coated with Alox before and after sizing.

I also just slugged the barrel and double-checked my boolits. Barrel slugged at .401 and boolits are at .4015... Boolits drop at .403.

Loads are very mild match loads and under 1000 fps, or close to it. Powder used was either WSF or Blue Dot. Fired 65 rounds and was able to get some OK accuracy results, but not what I was looking for. Best group was 2 3/8" at 25yds with a rest. Shot a mix of cast and XTPs but last 10rds were all cast.

Cleaned the bore with Hoppes and a .40 cal copper wire brush. Then noticed some lead left over and used a .45 cal one and scrubbed for probably five minutes.

It's not coming out.

Guess I will go to the store tomorrow and get something a bit stronger to remove the lead, but wondering why I'm getting issues. Took some pics just to confirm it's leading and not something else...

[Whitespider]

Yep, that's lead.
A couple of things...
1) I've never liked the results using Alox coating (or tumble lubing), every instance I've tried it resulted in sub-par accuracy and barrel leading. Others report good results that I've never been able to achieve.
2) Lyman #2 (even diluted with an unknown alloy) is too hard for handgun ammunition... especially at less than 1000 FPS. The boolit base won't obturate (seal off) the inside of the barrel and the hot gasses eventually find their way between the boolit side and barrel, resulting in what's called flame cutting. This will usually happen most prominently along the edges of the lands... which is what I'm seeing in your pictures.

As a general rule, when I see leading in a handgun the first thing I do is go to a softer alloy... however, as I said, I've never been able to eliminate leading using an Alox coating.
Also, as a general rule, at velocities under 1000 FPS I start with an alloy of 50/50 COWW/SOWW... at velocities over 1000 FPS I start with straight COWW (mostly to conserve my limited supply of soft SOWW).
The hardest alloy I'm using in any handgun is straight COWW with 2% tin added... including the magnums (however, I don't run them "balls-to-the-wall").
*

[randyrat]

-That is toward the muzzle, thinking the lube is giving out, try 2 coats of Alox.
-Is your sizing spud fat enough (brass squeezing your lead down when seating) Pull a couple bullets and measure.
- Any rough spots in the new barrel, not broke in yet.


I lose accuracy with alox or tumble lube when compared to my TAC 1 at about 2" or more at 25 yards..I've tried several times thinking I could save some time lubing and it's not worth the loss of accuracy. Plus I don't like the smoke of Alox

Soak it with a couple patches of Kroil and the lead should come out

[17nut]

Load a round or two without primer or powder. Pull the bullets and see if the cases are sizing the bullets down.
MANY have done that and wonder why their gun leads.

[williamwaco]

Load a round or two without primer or powder. Pull the bullets and see if the cases are sizing the bullets down.
MANY have done that and wonder why their gun leads.

DITTO. I have used nothing going but LLA for about5 years. At 700 to 1200 I have zero leading. Two things are critical though. Bullet fit and alox coverage. The coating should be complete but thin and DO NOT dilute it before you apply it.

[mdi]

I'd look at two things; case swaging bullet down and .4015" seems to be undersize for a .401" barrel. I would try some of the bullets unsized, .403" and see how that works. Five ten thousandths of an inch (.0005") isn't very much, just one half of one thousandths of an inch, and half that much one each side of the bullet...

[Idaho45guy]

Thank you so much for the replies!

I'm a bit concerned that the barrel slugged at only .401 when my Hornady XTPs are supposedly sized at .400. No wonder they aren't accurate in it...

[DougGuy]

My recommendation is to size to .402" for that barrel and if they won't plunk, throat the barrel.

Never liked LLA or any other tumble lube for that matter. 50/50+2% alloy with soft lube like Felix, SPG, or Tac1 and I never even need to clean a barrel. I get great accuracy, a slight bit of lube and powder residue left in the barrel and that's it. This is in 4 SA revolvers and 2 1911s.

Take your 45 cal brush and wrap it with a strand or two of genuine copper (not plated steel, *read* the label) chore boy and the lead will come right out.

[Idaho45guy]

Slugged the barrel with one of my XTP boolits and double-checked the cast boolit I already slugged and am pretty sure the barrel is .400 and not .401 as previously thought.

Took plenty of force to get the XTP though, which I checked and are at .400.

[Larry Gibson]

Idaho45guy

Are you using Lee's Liquid Alox?

Starting loads for both WSF (6.3 gr)and Blue Dot (9.2 gr) in Lyman's #4 CBH for the RCBS 185 cast out of a 10mm are above 1000 fps. Are you using less than the Lyman start loads? If so then the powders just may not be burning efficiently. I'd suggest a switch to Bullseye or Red Dot powders with the cast bullet.

Larry Gibson

[DougGuy]

Slugged the barrel with one of my XTP boolits and double-checked the cast boolit I already slugged and am pretty sure the barrel is .400 and not .401 as previously thought.

Took plenty of force to get the XTP though, which I checked and are at .400.

Both those slugs get enough springback to throw off measurements. Personally I like the fishing sinkers from walmart, dead soft and the hole in the middle allows for easier compression and better insurance against springback.

[williamwaco]

Idaho45guy

Are you using Lee's Liquid Alox?

Starting loads for both WSF (6.3 gr)and Blue Dot (9.2 gr) in Lyman's #4 CBH for the RCBS 185 cast out of a 10mm are above 1000 fps. Are you using less than the Lyman start loads? If so then the powders just may not be burning efficiently. I'd suggest a switch to Bullseye or Red Dot powders with the cast bullet.

Larry Gibson

Idaho,

I've been here a long time and when Larry Gibson speaks, I listen. You would do well to do the same.

[Idaho45guy]

Idaho45guy

Are you using Lee's Liquid Alox?

Starting loads for both WSF (6.3 gr)and Blue Dot (9.2 gr) in Lyman's #4 CBH for the RCBS 185 cast out of a 10mm are above 1000 fps. Are you using less than the Lyman start loads? If so then the powders just may not be burning efficiently. I'd suggest a switch to Bullseye or Red Dot powders with the cast bullet.

Larry Gibson

Yep, using the liquid Alox. Stopped by the LGS today and neither of those powders available. Decided to get a container of Winchester 231 to try as well. What are the characteristics of a good powder for cast? Slower? Faster?

[Larry Gibson]

Faster is better for target loads. Even if a power factor is needed. That 231 should work. If no power factor is needed I'd work up to just functional reliability. What are your accuracy requirements for your GSSF match?

The 2 coats of LLA should be sufficient. Suggest you don't switch back and forth between jacketed and cast loads w/o cleaning the barrel before shooting cast. The residue left by jacketed loads can (not always) cause the cast loads to lead. If you continue to have leading the unknown alloy you added probably had too much tin. Do you have any linotype?

Larry Gibson

[Idaho45guy]

Hmmm... When I test loads, I am switching between the XTPs and cast and going back and forth. I'll avoid that in the future.

No real accuracy requirements as I shoot off-hand at 5, 7, 10,15, and 25 yards. 10 shots and 15 seconds each distance. Pretty easy to get all Xs at 5,7, and 10 yards. It's the 15 and 25yd distances where I run into trouble due to the recoil of the 10mm and getting back on target, acquiring a sight picture, and squeezing the trigger in 1.5 seconds.

Last match I used the stock barrel in both Stock and Unlimited Class and shot reloads using 5.7gr of Unique behind a 180gr Hornady XTP. That was the most accurate load I've found with consistent sub-2" groups. But the recoil was a little more pronounced than the same load using WSF.

I don't have any linotype, and I was also water-dropping my boolits. I'll stop doing that, add some more lead, and not size the next batch I try later this week.

The Chore Boy and a new more aggressive Hoppes brush removed the lead, so I'm good to go again. Hoping to have time to do a little polishing of the feed ramp as well to see if that helps.

[KVO]

Granted you are loading for 10mm, I know .40 S&W is a loose analog at best. That being said...

For reference, I have two .40 S&W KKM barrels (Glock 22 and M&P40C) and both require taper crimping to 0.419", nothing larger at the case mouth will plunk. Neither responded well to W231/HP38. Best accuracy so far has been NOE 403-200 WFN with the deep HP, (180gr) and the Lee 175 TC converted to plain base. The NOE ever so slightly edges out the Lee in accuracy. I load both with 5.2 gr of Unique and size 0.401" and powder coated. Using a larger expander plug in the form of a tapered/shortened RCBS .40 cowboy expander noticeably improved groups as my boolits were swaging down when seated- .40 brass is hard!This was before the NOE expanders were available, I'd go that route given the option now.

[DougGuy]

Don't get crazy on the feed ramp. You can get into radiusing far enough that you take away support from the case. I recommend not more than a very tiny radius mostly in the center of the breakover at the top of the ramp, see red arrow..

[JohnH]

Take a look at the picture in this thread. http://castboolits.gunloads.com/show...the-Dan-Wesson This is out of the barrel of my Dan Wesson. I bought the gun in as new condition. The rifling of the throat just ahead of the forcing cone looks just like your barrel (but more heavily coated) Doesn't take long to dig it out when it gets crudded up, but it's been a while now since the problem has reared it's head. The barrel groove diameter is .426. Over time the condition has lessened. I bought a 7/16 ball cylinder hone and manually used it like a bore brush and polished up the barrel some but not so much that it altered the barrel dimensions. That helped a bunch. I also ran several hundred full house loads through the barrel to help smooth it out. It was leading so severely that in 400 rounds or less I had to disassemble the gun, take a pick and dig the leading out (see picture) It's been at least 600 rounds since I last had to do this and looking down the barrel with a mirror at the bottom reveals no leading. I'd suggest make up several hundred full house loads and run 'em through the gun to slick it up. As many as 500 won't hurt, a thousand wouldn't for that matter but I doubt it would take more than 500.