Questions about casting for a revolver

I shot my second load of cast boolits recently, these were 158gr flat points sized to .358 in a Ruger GP100. This went better than my last adventure with my 1911 because the boolits were not significantly undersized due to an inexperienced caster not realizing he wasn't getting good fillout :D

I had far less leading than I had with my 1911, but there was still some. Not excessive, I can clean it in about 10 minutes. Most of it gets concentrated in the forcing cone in the area just before the rifling starts. There was some leading in the first short bit of rifling, but not much. There was a good bit of persistent crud maybe 1/4 to 1/3 the way down the barrel stuck on the rifling. I don't *think* this was lead, but I'm not 100% sure. It looked more like powder residue, and I wonder if it kind of combined with burned boolit lube...I did kind of go a little overboard with the 45 45 10 this time.

The leading was, however, enough to impact accuracy negatively.

I have slugged my cylinders at just a tinge over .357 (they run .3572 to .3575). I don't know the exact dimension of the forcing cone short of the rifling, other that I know a .358 boolit will pass through it easily enough until the rifling is engaged. The groove diameter of the barrel is right at .357, almost exactly.

My max load was 4.8gr of Win231. I worked up to this increments as usual. The work up loads leaded the same as the max load. This "max" load is not by any means a powerful load, I just didn't think I needed to try to run magnum level pressures my first time out.

My boolit is a 158gr flat point cast from a Lee mold (358-158-RF). It was cast with wheel weight alloy (hardness should be between 8 and 10 BHN). All boolits were sized to .358 and tumble lubed with 45 45 10.

So my question is, what are the unique challenges to revolvers that can cause forcing cone leading? Looking for my next corrective step here. If the boolit isn't obturating well, that would indicate I need a heavier load or softer alloy. Or maybe .358 is undersized for my revolver? It's only half a thousandth over the size of my larger cylinder throats. Maybe it would be worthwhile to try to shoot them unsized in this gun? (My mold is dropping them between .358 and .360, slightly larger than what I get after sizing).

There are others with more experience who will hopefully weigh in but this is what I think.

If you are getting .002 variance in your casts, something is wrong. Maybe a bad mold or maybe bad technique. One bad cast, say out of round or the like, could cause your leading. I would check this carefully.

If that didn't find the problem, I would try shooting a few at .359 and see what happens.

as you said you may need a softer bullet if you are shooting low pressure loads. I don't have my loading manuals handy so I don't know about your load. Also don't know if it is in a .357 case or .38.

What mold?? LEE 6 hole?? If so, have you measured the bolts from ech cavity??
.358 should do it. Have you slugged your cylinder?? You may have a tight cylinder throat sizing your bolts down before they make it to the barrel.

SHiloh

If the leading halfway down your barrel is consistant with and barrel roll marks, the roll marks have moved material and created a tight spot most likely. Clean the barrel, lightly oil and tap a slug through the barrel to confirm the tight spot. The forcing cone leading you have already diagnosed. .3572-5 cylinder with a .358 barrel throat.

If this is a new pistol with a low round count it may take a few rounds to smooth out the bore of fresh machining marks. A couple hundred rounds of jacketed ammo should smooth things over. My new 9mm 1911 barrel leaded for probably the first 800-1000 rounds before is smoothed out and stopped leading.

Your 4.8 grains of W231 sounds fine for .357 Mag cases for a plinking load with soft lead bullets. In .38 Special brass it is approaching +P if your cartridge OAL is shorter than 1.50" with 158-grain bullet.

I expect that your cylinder throats are dimensioned more ideally for jacketed bullets than for cast, as most Ruger .357s are these days. If the gun were mine I would check the cylinder throats again to confirm their dimensions with gage pins, or by pushing soft, pure lead round balls through the throats, then measuring with a micrometer. If your .3572-.3575 dimension is indeed correct, honing the cylinder throats to .3580-.3585 will bring instant improvement and your soft-bullet, 900 fps load should not lead at all, if your forcing cone is also smooth and concentric.

I would agree with Outpost75.

It won't do any good to size larger than the throats since it is physically impossible for the boolit to exit the front of the cylinder any larger than the diameter of the throats so your cylinder at this point is pretty much a multi port sizing die. Cast boolits work best when they are .001" to .002" above groove diameter of the barrel, and to maintain that size, throats need to be .0005" to .001" greater than boolit diameter.

With an alloy of 50/50+2%, soft lube, boolits sized to .358" and throats sized to .3585" ~ .3588" you should have a clean bore with nothing but a little lube residue and powder residue remaining after a range session. If you would like to send a PM for details, we can get your cylinder to those dimensions rather easily.

Poor lube is number one. Then a FP that will rub away trying to clock the cylinder. soft lead that skids and opens gas channels. Your dimensions sound good so HARDEN the boolits and use a better lube.
Why are you using a FP in a revolver? Mule snot is not a lube. Better to spit on the boolit.

Go to Ben's Red or Ben's one step wax lube and I believe that your leading will be history.

I would re-read the cylinder/throat/barrel measurements again.

If you have any LLA left use it straight as per Lee's instructions. Add 2% tin to your WW alloy.

Larry Gibson

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Originally Posted by DougGuy

I would agree with Outpost75.

It won't do any good to size larger than the throats since it is physically impossible for the boolit to exit the front of the cylinder any larger than the diameter of the throats so your cylinder at this point is pretty much a multi port sizing die. Cast boolits work best when they are .001" to .002" above groove diameter of the barrel, and to maintain that size, throats need to be .0005" to .001" greater than boolit diameter.

With an alloy of 50/50+2%, soft lube, boolits sized to .358" and throats sized to .3585" ~ .3588" you should have a clean bore with nothing but a little lube residue and powder residue remaining after a range session. If you would like to send a PM for details, we can get your cylinder to those dimensions rather easily.

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Yes, 100%
But still a lube that does not work no matter. I never understood a coat of anything could lube a bore. Leave oil out of your car engine and put TL on the rings. I bet one stroke.
I will not go to the soft to obturate junk either.

Quote:

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Originally Posted by Larry Gibson

If you have any LLA left use it straight as per Lee's instructions. Add 2% tin to your WW alloy.

Larry Gibson

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NOT. Worst stuff ever. The jerk that made Alox a boolit lube should be beat with a cane.
To temper it with other waxes is folly. You can do nothing to make it work.

I must be the exception to the rule because LLA works just fine for me, but then I had to learn to follow the directions and not use it as I saw fit.

I have the following Lee TL moulds;

TL314-90-SWC
TL358-158-SWC
TL41-175-SWC
TL41-210-SWC
TL430-240-SWC

And have used the;

TL356-124-TC
TL452-200-SWC
TL452-230-TC

I use a ternary alloy with the antimony and tin balanced. I use them from 700 to 1200 fps in various handgun and rifle cartridges in handguns and rifles. I put a very light coat on the bullets, let them dry completely, size them and then put another light coat on them letting them thoroughly dry before loading. I get excellent accuracy and have yet to have the "leading" problems others seem to have.

I also lightly coat and let thoroughly dry commercial cast bullets that have the hard wax lube and always lead. With the light coat of LLA they lead very little but I do not drive them to magnum levels. I just recently did about five hundred 44s that way and loaded them over 8.5 gr of Unique....excellent accuracy and no leading that didn't clean out with a normal cleaning.

A light coat of LLA on 375 and 457 RBs and thoroughly dried and then loaded over a mild load of Bullseye has accounted for many rabbits, grouse and ptarmigan out of my 375 H&H and TD 45-70s. ......again with excellent accuracy and no leading.

LLA also makes an excellent release agent when bedding actions. Heated up by leaving the bottle in hot tap water for 10-15 minutes it applies evenly and dries quickly. I have used everything from Devcon to AccraGlass with excellent release. The residue cleans off very easily with normal gun cleaners.

I even put some on my fingers and coat the bore riding noses of 311299 and 314299s I am driving hard.

Works for me.......:drinks:

Larry Gibson

I would have the cylinder throats opened up to .359 and size my bullets the same

I vote with those who vote to open up the cylinder throats. I had that done on a Ruger Vaquero 45 Colt that went from pie plate to golf ball size groups after correction.

Put me down as another happy user of Lee Liquid Alox. I dare say I have used it on at least 40,000 rounds in the last 20 years, (maybe twice that--My bookkeeping , especially on my plinkers consists of checking the ammo can and refilling it if low.) I have used it in many applications ranging from 75 grain 38 special plinkers at BB gun velocities, up to a 30-40 170 grain gc at 2300 FPS with good to excellent results. I now use Ben's liquid lube, which is quicker drying, for most of my pistol applications, but for rifle stuff, and the 9mm, I still use LLA.

Larry's experience parallels mine almost exactly. Use it right, one application, then let dry, size and then a second coat. Now one thing I will say, most of the pictures I have seen look to have a little too light a coat. IME, if the boolits don't have a bit of a golden bronze haze on them, you don't have enough. Some place there is a Photo of some Wadcutters, I think made by Ed Harrison, that look just about perfect. If my google foo were better, I'd try to copy it here.

Attachment 189179boolits number 3 and 7 are good examples of what I mean, though number 4 is acceptable for low velocity work. (1 and 2 hadn't been lubed yet when this picture was taken, 5 and 6 have Javelina 50-50 and a light coat of Ben's Liquid Lube.

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Originally Posted by rintinglen

I vote with those who vote to open up the cylinder throats. I had that done on a Ruger Vaquero 45 Colt that went from pie plate to golf ball size groups after correction.

Put me down as another happy user of Lee Liquid Alox. I dare say I have used it on at least 40,000 rounds in the last 20 years, (maybe twice that--My bookkeeping , especially on my plinkers consists of checking the ammo can and refilling it if low.) I have used it in many applications ranging from 75 grain 38 special plinkers at BB gun velocities, up to a 30-40 170 grain gc at 2300 FPS with good to excellent results. I now use Ben's liquid lube, which is quicker drying, for most of my pistol applications, but for rifle stuff, and the 9mm, I still use LLA.

Larry's experience parallels mine almost exactly. Use it right, one application, then let dry, size and then a second coat. Now one thing I will say, most of the pictures I have seen look to have a little too light a coat. IME, if the boolits don't have a bit of a golden bronze haze on them, you don't have enough. Some place there is a Photo of some Wadcutters, I think made by Ed Harrison, that look just about perfect. If my google foo were better, I'd try to copy it here.

Attachment 189179boolits number 3 and 7 are good examples of what I mean, though number 4 is acceptable for low velocity work. (1 and 2 hadn't been lubed yet when this picture was taken, 5 and 6 have Javelina 50-50 and a light coat of Ben's Liquid Lube.

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Going by your picture, I might have been going light on my lube. I'm not using straight alox though, I'm using that 45 45 10 mixture. I didn't make it, bought it from White Label.

I spent years and years testing lubes. The difference is amazing. Why is an undercoating car rust preventative a boolit lube when all my cars with Zeibart rusted faster then bare metal? yes Alox was for undercoating.
Low flash point, smoke and burns in the bore. Mix with bees wax, why not safflower oil or peanut oil?

I'm with Al and James. I use 45-45-10, apply a light coat, let dry, resize, second coat, dry and reload. No leading on any of my rifles (300 BLK, 308 Win, 45-70, 44 Mg) with or without GC and velocity from 1,050 fps (subsonic for 300 BLK) to 2,100 fps (308 Win). Easiest lube to use and works wonderfully.

Sent from my SM-T377P using Tapatalk

I apologize and know I irritate some. But I have had leading from two things, Too soft a boolit with some coating, moly or graphite and Alox, coated, sized and coated again. But I shoot full hunting loads all year and have revolvers that have not seen a bore cleaning in 6 years.
I know some will make it work but I can't.
I don't like a hard lube or a slippery lube but my friend Glen makes CR and I can say nothing wrong, it does work. Even some LBT lubes are not good in a revolver. Hard blue is one. Soft Blue and the old Magnum lube is better. Orange Magic fails. Moly packed lubes showed nothing. The old 50-50 can work some. Felix has out shot so many that it is my standard for tests.