Slugged my K-38

[Drm50]

I got several S&Ws and only leading I ever had was with Speer 45 SWC. I was shooting at 700fps with Unique. Worst leading I have ever seen. Out of 25-5, 83/8” the lead was working out of muzzle by 18th shot. Looked like Elmer Fudd cartoon but lead came out easy with just bronze brush.

[murf205]

This is why commercially cast bullets sometimes lead; for the commercial casters 12 BHN is considered "soft" and you don't get the obturation.

Don

That, and the fact that a lot of commercial casters use beveled base molds to facilitate easy drop out of the mold. Almost all the leading I've experienced is from bb boolits. It is kinda like inviting the gas up onto the base.
The reason I recommend cylinder reaming AFTER everything else has been tried is because it worked...for me in 2 instances. I have a M24 Smith&Wesson that had .429 throats and a couple that were .4285 and it leaded in spite of trying 3 different lubes and about 6 differrent powders. I drove 429421's fast, slow, and medium but the lead was still there, not to the point of unshootable but still there. The barrel is a EDM rifled barrel and it looks like a mirror. I have a 44 Hand Ejector made in 1926 that has .432 throats and it is the most accurate 44 I own, so I reamed the throats to .431 and it changed the game instantly.Attachment 268698These targets are what I finaally got the Model 24 to do. It is not a match grade gun but it does not lead anymore.

[catboat]

It has not been mentioned yet. You may have an issue of thread choke. The bore /groove diameter inside the frame (throat) may be squeezed down 0.001-0.002", as the threaded barrel is tighter in the frame. If thread choke is present, a bullet is sized down to that choked down (reduced) bore/ groove diameter, and obviously stays in that reduced diameter as it goes down the barrel. This reduces accuracy, and causes leading ( at the throat (shear) and/ or in the barrel ( gas blow by).

You can determine if you have thread choke by slugging the bore ( from the muzzle) and using a few cast bullets. Lube the bore, and push one bullet in an inch or two, then tap it out back to the muzzle.

Make a couple cut off dowel pieces that just fit inside the frame, and put them in from the throat side. Depending on barrel length, you will need 3-4 dowel piece about cylinder length length, and one dowel piece about 1/2 cylinder length. The "1/2 cylinder length" dowel piece is used to allow enough space behind the dowel to permit you to place something hard behind it to apply force toward the muzzle to remove the slug.

Measure the slug (even if it has 5 grooves).

Repeat, making a slug down another 1-2". Remove from muzzle end. Measure.

Then push a slug from the muzzle through the throat, and catch it. Measure.

If the pushed-through slug is smaller diameter than the other slugs ( which did not pass through the throat), then you have "thread choke." It needs to be removed for best accuracy.

Two ways to correct for thread choke: fire lapping, or having the barrel modified to a "Taylor throat." ( reamed /tapered throat. Both remove the tight spot in the barrel, and usually improves accuracy, and reduces leading.

Then check cylinder throat diameters. They should all be uniformly the same diameter, and about 0.001" larger than the barrel's groove diameter (without thread choke restriction). You may need to have the throats reamed open ( not opened with an abrasive strip on a dowel , chucked into a drill. This creates an oval-shaled, non-parallel cylinder throat which is less-than-ideal for best accuracy).

Repeating the concept and strategy: The proper diameter bullet will then just fit through the cylinder throats, with just a bit of force ( ie, you can push the bullet through each cylinder throat with a dowel or pencil.). The bullets should not fall through the cylinder throats with just gravity. You want the cylinder throats about 0.001" larger than the "thread choke less" groove diameter.

There are multiple areas to measure, and possibly correct for getting the most out of your revolver. The solution is likely not just changing bullet diameter itself.

[Cosmic_Charlie]

This is a 1956 vintage gun with a pinned barrel so I doubt thread choke is the issue. Plus I felt nothing as the bullet approached the forcing cone. And it shoots nice groups. I just don't like the leading even as minor as it is.

[murf205]

What part of powder coating do you not like, the process or the colors? Smoke sell a clear powder that looks like, well, clear. It might just be worth your time to try some pc'd boolits just to see.

[catboat]

Do your bullets ( not loaded cartridge) fall through the cylinder throats, or do the need a push with a pencil? I seem to remember reading that some s&w model 25 had large throats ( .454"++). If you are shooting a .451-.452" lead bullet, you will likely get gas blow by, and create leading.

Use a pin gauge, or place a lead slug in each cylinder, tap it to expand a bit, then push a different bullet through each throat and get the slug's diameter for each throat. You obviously want the slug bigger than the throat before you tap it through, so the slug will be sized to the throat diameter for accurate dimensions .

[USSR]

I seem to remember reading that some s&w model 25 had large throats ( .454"++).

Actually, it is MOST of the Model 25's, until they dropped the pinned barrels.

Don

[Cosmic_Charlie]

What part of powder coating do you not like, the process or the colors? Smoke sell a clear powder that looks like, well, clear. It might just be worth your time to try some pc'd boolits just to see.

Mostly just the extra time involved verses tumble lube. I figure if I can shoot 1650 fps tumble lubed boolits without leading in my .308 I ought to be able to do it at 800 fps in my revolver. I powder coat my 9mm boolits.

[DougGuy]

My .358 boolits won't easily push through the throats either so I figure the throats are really close to the groove diameter.

If a boolit won't push through the throats without force, then the cylinder is at this particular moment in time, a multi port sizing die. So it's either sizing to the groove IF the throats are indeed the same size as groove diameter, or slightly smaller than groove. Just sounds like not quite enough boolit to swage into the rifling enough to make a good seal.

[Cosmic_Charlie]

Well it is curious. My 24-3 shoots .432" boolits because it has large throats. Have not bothered slugging it because it is accurate and does not lead. My Super Blackhawk uses .431 and also is trouble free. My Model 60 Pro likes .358 boolits. But my two oldest Smith's have very tight geometry. Thanks for all the input fellas. Now I get to try a few things.

[Cosmic_Charlie]

Powder coated .357 boolits did the trick. I also tried some 16/1 alloy for the .357 and 8.7 HS 6 but have not shot them yet.