.38 Super muzzle leading

[Grandpas50AE]

Earlier this year I began a project to cast boolits for the .38 Super. During the experimentation I discovered the barrel was out of SAAMI specs and had chatter marks, which caused leading at the point where the chatter marks were. Couldn't lap the barrel because it was larger bore size than SAAMI spec, so I decided to have a new barrel put on. Last week I received my Kimber back from Wilson Combat with a new Wilson barrel, and fired my first set of cast through it. There is some leading at the muzzle end of the barrel - last inch and a half. I seem to remember from earlier discussions that this is usually an indicator of the lube running out before the boolit exits. Is my memory correct on this? The boolits are 9.5 BNH, sized .002 over groove diameter, plain base SWC, velocity 1200 fps using Javelina 50/50 lube. The barrel is a 5" barrel. Would it be likely that removing the lube and replacing it with White Label BAC might get rid of the leading? Thanks for any feedback.

[Cherokee]

I load/shoot 38 Supers with CB @ 1200-1350 fps and have no leading problems from my Briley & King barrels which are .355" Agree that leading at muzzle end is usually lube related. I use Lars CR for all my CB's and my boolits are sized .356". I have a nice lube star on the crown after a shooting session. The Lyman 356402 and Lee 356-120TC (lub groove) have proven to be my most accurate CB's.

[Grandpas50AE]

Thanks for the reply Cherokee. I am using a boolit cast from the Accurate Molds 35-140 mold. I think I will take a Q-Tip to 50 of the boolits and remove the old Javelina lube and run the back through the sizer with BAC. I'm sizing them at .357 (mic'ed) so I have a good fit.

[Shiloh]

Been using BAC exclusively for several years now. No leading with GC'd rifle boolits at 2100 fps, as fast as I have taken them.
None on flatbase .357 mag boolits at 1350.

Shiloh

[MtGun44]

I shoot similar alloy at 1350 or more in .357 Mag with no issues and commercial cast in
.38 Super at about 1250 fps with no issues, including the crayola lube. How much lube
capacity on the boolit? Sounds like running out of lube.

Bill

[Harry O]

I have no specific experience with this caliber (other than using .38 Super brass in a 9mm Largo I have). However, I have had a couple of problems with purchased bullets leaving a little leading at the muzzle with rifles rather than handguns, though. In those cases, a quick and easy fix was to take some of the offending bullets and put a thin coat of Lee Liquid Alox over the top of them (both bullet and existing lube). It worked with the ones I tried it on. YMMV.

[runfiverun]

sounds more like running out of oils in the lube,or the lube is not flowing any more.
just for the fun of it you could wet a q-tip with some atf/2 stroke oil/castor oil, and run that around the boolits you have lubed now.
adding carnuba to the lube raises the melt temp of the lube, you need to lower it to stay in the wet stage longer.
i'd almost bet your leading is preceded by a small gunky spot of smeared lube.

[williamwaco]

If you have a bunch of these bullets and don't want to unlube/relube them consider re-lubbing them "as-is" with a tumble lube.
I have done it several times with bullets that were leading like you describe.

See:


http://reloadingtips.com/pages/lla_bullet_lube_2.htm

[geargnasher]

Running out of lube is a myth. You have other problems, like not enough tin in your mix to control the antimony wash or the boolit alloy can't take the shear force of the lands at the velocity and pressure curve of the load you're using.

Study what Runfiverun mentioned, your pistol might be a candidate for Speed Green, Lotak, or Run's "Simple Lube" (recipe in the lube forum) to get some more "free" slickum going on. This will help reduce the shear force of the boolit against the sides of the lands which can cause alloy failure and gas leaks on the trailing edge.

I shoot .38 Super with hot loads of Power Pistol, water-quenched 50/50 WW/pure alloy, and Felix lube out of a Kart barrel in a 1911 and have zero leading. Things have to be in balance.

Gear

[Grandpas50AE]

sounds more like running out of oils in the lube,or the lube is not flowing any more.
just for the fun of it you could wet a q-tip with some atf/2 stroke oil/castor oil, and run that around the boolits you have lubed now.
adding carnuba to the lube raises the melt temp of the lube, you need to lower it to stay in the wet stage longer.
i'd almost bet your leading is preceded by a small gunky spot of smeared lube.

Runfive - You could be quite correct on the lube running out of oils too soon, as this is OLD Javelina lube that seems to dried up alittle over the years (last of the batch I bought years ago), and I think the switch to the fresh BAC I bought last spring will take care of this problem. I melted the old lube out of 50 boolits last night and re-lubed them with BAC, then loaded them to go shoot on Saturday. I'll let you all know how it has worked out. Everyone here has been very helpful, and this is the strength of this forum.

[Grandpas50AE]

If you have a bunch of these bullets and don't want to unlube/relube them consider re-lubbing them "as-is" with a tumble lube.
I have done it several times with bullets that were leading like you describe.

See:


http://reloadingtips.com/pages/lla_bullet_lube_2.htm

Good idea, but I don't keep any dip lubes around. I still appreciate the tip.

[Grandpas50AE]

Running out of lube is a myth. You have other problems, like not enough tin in your mix to control the antimony wash or the boolit alloy can't take the shear force of the lands at the velocity and pressure curve of the load you're using.

Study what Runfiverun mentioned, your pistol might be a candidate for Speed Green, Lotak, or Run's "Simple Lube" (recipe in the lube forum) to get some more "free" slickum going on. This will help reduce the shear force of the boolit against the sides of the lands which can cause alloy failure and gas leaks on the trailing edge.

I shoot .38 Super with hot loads of Power Pistol, water-quenched 50/50 WW/pure alloy, and Felix lube out of a Kart barrel in a 1911 and have zero leading. Things have to be in balance.

Gear

Gear,
Once again you provide very sound observations, so I'll give you a little more info. I'm using 6.5 gr. SR4756 on the Accurate Molds 35-140S boolit. SR4756 is very close to Power Pistol in load map characteristics, and I use both with great success. I'm thinking that the lube is old and lost some of its "slickum" from sitting for too many years in the garage. When I moved to my current house 14 years ago, it took 5 years to get the loading room put together, and 2 more years to get the casting bench set up. As always, I appreciate your observations and suggestions. You may be right about the lube grooves not being big enough to hold enough lube, but I only want to change one thing at a time. If the BAC doesn't get the job done, I will probably contact Tom at Accurate to modify the mold design to increase the lube groove size a bit. Thanks for responding.

Everyone have a great Thanksgiving.

[geargnasher]

I think your lube grooves are just fine. You mentioned you're using a 9.5 bhn alloy, and while bhn isn't the whole story, I would consider that to be too weak for your purposes regardless of what composition it is that yields 9.5 bhn. Even if it didn't lead, I wouldn't expect that alloy to achieve the best accuracy.

You didn't describe exactly where in the barrel the lead is depositing, but if it's at the root of the land on the leading edge the alloy is probably too soft or lube is just miserably inadequate, if on the trailing edge root it's likely the same sort of thing, or the boolit is skidding a bit at launch and opening up the engraves to fail further down the barrel at peak pressure, and if it's streaking down the middle of the groove you have rough spots, a restriction, or sudden and severe loss of pressure. I don't think you're skidding or losing pressure with the powder and load you're using, but the alloy may be a tad soft and the dried-out lube isn't helping things.

If lube doesn't fix it, try loading some with mild loads of 231 or Unique. If that fixes it, try a tougher alloy, preferable a water-quenched or heat treated low-antimony alloy.

How is the accuracy with the loads that were leading toward the muzzle?

Gear

[Grandpas50AE]

The leading is in the last 1 to 1-1/4" of the barrel (muzzle end), on the grooves leading edge. The alloy is 50/50 COWW and pure lead with 2% tin added back in for fill-out. Accuracy was excellent at 15 yards, and I only loaded 50 rounds for this first test. I had a few rounds I pulled, but there were about 22 rounds in each of two, single-hole groups measuring about 1-1/4" each. I shot 25 at one POA, and 25 at a different one to see if the second set would spread, and since it was an indoor range where off-hand is the only style available, it isn't the most effective way to measure groups. Even so, my blood sugar was falling off (diabetic) so that's about as good as I could do under the circumstances. I'll let you know sometime this weekend how the change in lube works.

[runfiverun]

you all are heading somewhat where i was going with the dirty smudge just before the leading occurs.
i was having an issue with what appeared to be leading in a 44 mag.
it was lube smears in the bbl and a trace of leading behind that, i could move the smearing up and down the bbl at will by changing powder speed.
i took to calling it the point of relaxation [where the pressure from the powder fell too low to keep pushing on the boolit]
the thing is, if you pushed harder/longer you'd see the grey poof from this set up.
i'd try the lube,then water dropping the alloy,then if still not good nuff, the load.

[geargnasher]

Recast the boolits, this time don't overtin the alloy. Mix what you have 50/50 with more 50/50 and don't add any more tin. Water quench them right out of the mould and wait three weeks before shooting. That little tin detail makes a BIG difference, as will the water-quenching.

Gear

[Grandpas50AE]

Finally got a chance to test with just changing the lube to BAC. Not as much leading, but changed to last 1/3 of barrel. I'm thinking Gear is right on the alloy being a little too soft for this application, so I'm going to melt the lube out of them, heat-treat and quench, then re-lube with BAC and try that. I've got about 100 boolits left of the batch, so I'll give this a try. When I fire up the casting pot (probably sometime next week while I'm on vacation) I'll put the 50/50 alloy in with some straight WW ingots to yield a 75/25 alloy (coww to pure) and not add any extra tin back in, and water drop straight from the mold. That should put my alloy in the 12 to 13 range for BNH.